MadModder

Gallery, Projects and General => Project Logs => Topic started by: awemawson on September 24, 2014, 12:29:06 PM

Title: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 12:29:06 PM
Sorry about this chaps but I'm starting another re-build thread that might go on for the odd page or two  :ddb:

I bought this machine on a whim back in October 2011. It was basically working but was in dire need of some TLC. No preventative maintenance had been done in years, various panels and covers were missing, and although working, the Fanuc 6 CNC control was hard to use due to most of it's indicator bulbs being blown, and several key buttons either missing or broken.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 12:42:50 PM
So what is a "Wire EDM Machine"  :scratch:

Well the EDM stands for Electro Discharge Machining - otherwise known as spark erosion. In this machines case, the work piece is attacked with a thin brass wire (0.25 mm diameter) and the electronics creates a controlled discharge between them. A gap is maintained across which the discharge occurs explosively dislodging minute bits of the work piece and also the wire. For this reason the wire is 'use once only' and runs off a feed spool, via several cunning mechanisms, and ends up on a take up spool ready to go to the scrap man. The gap between the work piece and the wire is 'flushed' with de-ionised water to clear the removed material, maintain electrical isolation and very importantly, cool the wire.

Mean while the CNC controller moves the work piece by servo action in X & Y taking all sorts of parameters into consideration to keep accuracy of the part.

A second set of servos can move the wire in 'U & V' tilting the wire up to 20 degrees to make three dimensional cuts.

So in concept you can imagine it as a band saw that uses an extremely thin blade, and can cut tool steel up to 200 mm thick

Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 12:49:16 PM
So the wire starts life nice and fresh and new on the feed spool, which is gently biased in reverse to stop it 'running on'. It then passes through a set of tensioning rollers and brakes, and a 'wire break sensor' eventually being presented to the lower wire guide, which is a diamond with a hole in it. As the wire is electrically 'live' all the parts have to be insulated from the body of the machine.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 12:54:35 PM
Near the lower guide there is (or rather SHOULD be - more on this later) a sliding contact that energises the wire. This is a fat disk of Tungsten Carbide over which the wire passes. This contact is duplicated near the upper wire guide so that current is fed into the wire both from below and above the work piece.

Both wire guides have co-axial water feeds, the flow of which is manually controlled to form a thin 'string' of water surrounding the wire
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 12:57:26 PM
So having passed through the work piece and also through the upper guide, the wire goes through another set of tensioning rollers and on to the take up spool
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 01:02:05 PM
The 'table' on which the work is positioned is an open centered rectangle giving the machine a working envelope of  450 x 650 x 200 mm, (and up to 300 kGs  :bugeye:)

This table is moved by servo control from the Fanuc 6 control and attached to the side of it is a 'dry run plotter' that draws a representation of the part on paper without actually cutting metal
Title: Re: Titivating a Wire EDM Machine
Post by: chipenter on September 24, 2014, 01:08:19 PM
You don't do things by halfs Andrew do you ?
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 01:09:10 PM
"You don't do things by halfs Andrew do you ?"

Well Jeff - if you're going to do something you may as well do it properly  :lol:


The machine works - make good parts but is pretty slow - really a 'lights out and leave it' sort of operation.

So far I have got the Fanuc 6 and its operation panel sorted out, managing to beg borrow and steal compatible parts. And I have upgraded its memory so it can store larger programs.

Memory on the Fanuc 6 is 'Bubble Memory', a technology that came and went over a very short space of a few years:

http://en.wikipedia.org/wiki/Bubble_memory

I have also replaced the tiny bearings in all the wire guide pulleys - a fun exercise as the pulleys in the main are very delicate ceramic with press fit stainess steel bearings.

I've also re-made most but not all the missing tin work panels
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 24, 2014, 01:26:01 PM
So what's triggered this flurry of postings ?

Well glancing through eBay as I'm prone to do, I came across some of the lower contact electrodes and thought it was about time I sorted mine out.

The machine was originally an 'Automatic Wire Feed' variant - ie you positioned the table so that a hole lined up with the wire guides, and it would thread itself. Very handy indeed as threading 0.25 mm brass wire through equally small wire guides standing on your head to get at them is a bit of a pain. Sadly this feature proved to be unreliable and at some time was removed from it.

In the process I suspect that the lower assembly was replaced with one from a similar but different machine and there is no provision for the lower tungsten carbide contact to be mounted. The relevant wire is fixed to the insulated centre of the lower pulley and does nothing at all.

The net result of this is that the machine can only operate at half the current it is designed for without melting the wire.

So my intention is to re-design the layout of that area so that the contact can be in the wire path. Problem is, this machine (like me!) is rather long in the tooth (mid 1980's) and the 'stainless' support arm is badly corroded.

I've avoided delving in before due to the fact things are very likely to break being undone. But now I'm setting out hopefully to fix it and I'll be glad to have you all along with me as I do it.  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: hermetic on September 24, 2014, 02:33:47 PM
I.m looking forward to the Journey Andrew. I gather from your description that this machine operates with the wire through the workpiece cutting a bit like a bandsaw?
Phil
Title: Re: Titivating a Wire EDM Machine
Post by: NormanV on September 24, 2014, 04:38:55 PM
This is going to be interesting.
There was an article in 'Model Engineer' No 4432 15th June 2012 that told the story of using an EDM machine to cut a cylinder block for a 4"scale traction engine model.
Title: Re: Titivating a Wire EDM Machine
Post by: dsquire on September 24, 2014, 09:08:35 PM
Hi Andrew

I thought that it was kind of quiet on your corner of the island lately. I guess that is because you were working behind closed doors bringing yet another machine back to life. You will have a good following on this I am sure.  :D :D

Cheers  :beer:

Don
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 03:04:20 AM
I.m looking forward to the Journey Andrew. I gather from your description that this machine operates with the wire through the workpiece cutting a bit like a bandsaw?
Phil

Phil, there is an excellent free downloadable book describing the process here:

http://reliableedm.com/Complete-EDM-Handbook.php
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:35:40 AM
So where to start  :scratch:

Realistically I need to remove the entire lower arm assembly to be able not only to assess what is there, but also to be able to do whatever machining is needed to mount the contact and re-locate the guide pulley.

This is what we are dealing with:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:38:34 AM
Now the arm is mounted onto the body of the machine using four largish cap screws - unless I can undo those then probably the whole exercise is a waste of time.

So I tentatively loosened then re-tightened each one - surprisingly they shifted quite easily. At this stage I presumed that there would be alignment dowels to accurately locate the arm.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:40:52 AM
OK that hurdle jumped I had the confidence to start on the other end of the arm and strip off it's water feed and electrical connections
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:45:40 AM
So now I could withdraw the rather stiff and brittle water feed pipe and co-axial screened power feed wires which are threaded through the arm assembly.

Last remaining bit to take off was the 'wire break detector' which is simply a microswitch with a long wire actuator that has a ceramic tube threaded on it. This was one of the bits that I'd fixed when I got the machine. A previous owner had just cut it out of circuit when it failed  :bugeye:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:52:24 AM
OK so now the arm bolts can be removed to free the arm. Easy enough and I was surprised to find that in fact there are no locating dowels for the flange - just a 'shelf' that it rests on.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:54:17 AM
So what was revealed ?

Well as I expected rather a lot of corrosion - in fact it looks a horrid mess!

Have some pictures:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 04:57:39 AM
Now none of the corrosion gives any structural issues, but no doubt undoing some of those cap head screws holding the blue insulator will be 'fun'

I decided, true to form, to dunk it in a bucket of warm citric acid solution for a few hours and see what happens. Never used it before with stainless steel.
Title: Re: Titivating a Wire EDM Machine
Post by: lordedmond on September 25, 2014, 05:03:36 AM
Andrew

Now you know why they say water is the universal solvent ,deionised and dis tiled are the most active both will try to leach back the minerals removed from them. That why you should never drink distileled water it will leach back from your gut

Good luck with this major project

We have a edm machine at the club that uses shaped electrodes and paraffin as the electrolyte/flushing liquid.


Stuart
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 05:22:53 AM
Thanks for the good wishes.

Perhaps yours is a bit like this one ?

http://madmodder.net/index.php/topic,9319.0.html
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 06:38:15 AM
The Tungsten Carbide contact electrodes have just been delivered. I didn't go with the eBay ones, as although they were somewhat cheaper they weren't quite the same size as the originals. They would have worked fine I'm sure. However I reasoned that if I could source ones to the original spec at least in the future replacements would be available.

Worth noting that these contacts do not revolve - the wire slides over them and eventually wears a groove, whereupon you slacken their mount, turn a fresh face to the wire, and tighten up.

I've just taken a tentative look at the bucket of citric acid - quite a bit of progress but it needs more time, after all it's only had barely an hour and a half so far. At least the heads of the countersink cap screws that retain the blue insulator can now be distinguished from the rest of the mess  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: lordedmond on September 25, 2014, 07:34:58 AM
Yep Andrew very simler not used it myself it came out of Ratclffe on Soar PS :D


Stuart
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 09:17:03 AM
I decided that it was worth soaking the entire arm in citric acid, so I transferred it to a tote box that was almost big enough (!)  - it'll need at least an over night soak if not a few days
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 25, 2014, 09:18:23 AM
However if you contrast these two pictures you can see it is progressing
Title: Re: Titivating a Wire EDM Machine
Post by: hermetic on September 25, 2014, 05:04:26 PM
Thanks for the link to the book Andrew, very interesting, I get it now.
Phil. :bow:
No experience with this type of kit, I will continue to follow with great interest.
Learning all ze time!
Title: Re: Titivating a Wire EDM Machine
Post by: micktoon on September 25, 2014, 06:18:55 PM
Hi Andrew , Interesting post and well explained. It looks like the acid is doing its job, good luck with the project, I will be interested to see it running, I remember seeing skips of the used wire in the scrapyard.
  Cheers Mick.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 26, 2014, 11:09:49 AM
A few more hours in the citric acid bath and at last things have come up reasonably clean - certainly enough for me to be able to start dismantling with some confidence of success.


Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 26, 2014, 11:11:19 AM
My main concern was getting the insulators off without cracking them. They are machinable ceramic, so could be re-made, but that stuff is horrendously expensive
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 26, 2014, 11:12:47 AM
The other metal bits were less of a concern. Amazingly some of the screws actually unscrewed, however several had lost too much material from their heads in the hex socket and had to be carefully drilled out
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 26, 2014, 11:14:18 AM
The part that holds the bearing for the lower wire pulley will need re-making as it is going to have to hold the new contact electrode as well as the pulley - this is it:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 26, 2014, 11:15:51 AM
I seem to remember that I had to replace that shaft that sticks out of it when I re-did the bearings when I got the machine in the first place.

Now to try and remember how they all fit back together  :scratch:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 27, 2014, 10:23:26 AM
A little bit of progress today - mainly taking decisions as to which way to jump.

It would have been much easier to mount the new Tungsten Carbide contact to the outer side of the wire (ie lhs looking at it), this way I could re-use the existing pulley mounting. However it would be in the way when re-threading the wire and make an already tediously hard job harder.

So I decided to let the wire touch the contact tangentially, and  wrap it round the contact by taking the pulley nearer to the machine body - ie to the right as you look at it. However this meant slightly modifying the arm to make room for the pulley
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 27, 2014, 10:27:21 AM
It was a bit like cutting hard swiss cheese - all very porous.

In the picture below, the two white nylon bars represent where I will mount a delrin insulator onto which the contact will mount using a stainless steel stubby axle. The end of this axle will take the power connection.

Slab of delrin, and a bit of stainless bar to re-make a longer pulley mount are on order, along with numerous stainless cap screws
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 03:45:58 AM
Being at that frustrating point of 'waiting for bits to arrive' I've embarked on trying to clean up and restore the concertina 'curtain' arrangement that is suposed to stop water splashing out of the working area of the machine.

When I got my machine the curtains were flapping about, the far one is torn in several places, and the sliding seal mechanism that surrounds the arm and holds the inner end of the curtains is missing
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 03:50:37 AM
Now a few years ago I had the opportunity to rescue parts from a 'Model L' Fanuc Tape Cut (mine is a 'Model M') - the 'L' has a smaller operating envelope, so for instance the arm that I'm working on is a smaller cross section.

However I did manage to get the curtains, and although encrusted with detritus it turns out that they are the same size (110 mm tall) as the Model M. So after a week end soak in citric acid they've come out perfectly usable - a result  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 03:53:43 AM
From the donor machine I also got the sliding seal arrangement, and although too small for my arm at least shows me how it's supposed to be. So this also was cleaned up for inspection - all these bits were very heavily encrusted in, presumably, whatever the machine had been cutting, which had then oxidised into a solid mass
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 04:08:01 AM
The actual seals are 10 mm square closed cell neoprene foam, which eBay has provided me with  :thumbup: And rather than bend up the complicated shape out of stainless sheet, I'm going to machine a version from 20 mm square stainless bar, with a 10 mm groove to house the seals.

What I hadn't appreciated, when I robbed the donor machine, was that I had obtained a pair of 'grooved ditch' wire guides and their mounting. I frankly hadn't recognised them as what they are. These are a slightly less precise method of location for the wire, but vastly easier to thread. Using them will need quite a bit of adaptation - the upper one will just bolt straight on, but the lower one will need a bit of engineering, and both will need provision for flushing nozzles.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 04:15:21 AM
Note the delicate 'salmon pink' copper deposits - these were covered in crud like everything else, and a dip in the acid bath has cleaned them, but I suspect this machine had been cutting copper, and the copper oxide crud, and the acid has plated the stainless steel ! It'll come off easy enough later.
Fitting these will be another project - they'll be put to one side for now.

When I got access to the 'Model L' it had already been pilfered sadly, but I did manage to get the entire Fanuc 6 cnc control with the exception of it's operator panel and screen as that had already gone. Poor thing was under a tarp in a back alley behind a factory when I got to it, and was in a very sorry state.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 12:22:42 PM
So now to start dismantling the upper and lower runners for the curtain - all pretty fouled with accumulated build up of residues, now caked rock hard.

Starting with the brackets that tether the curtains on the outer edges
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 12:25:37 PM
Then remove the 'upper track' - easy so far but this revealed a problem.

Some plonker in the past has mounted the lower track using ordinary HT cap screws, not stainless ones  :bugeye:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 12:29:23 PM
Only two rusted cap screws, but in a confoundedly awkward place. As they are so low down on the base, the tray that surrounds the work space limits access.  :bang:

The rear one had entirely rusted the head off, and the front one was so nearly completely gone that there was no chance of gripping it to unscrew, so I ended up grinding the remains away to allow removal of the lower runner
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 12:31:17 PM
This has at least given me access to clean the work area up a bit - I'm actually amazed how well it's come up, and I'm not finished yet.
This is the result of the 'first clean'  :
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 12:35:49 PM
Now to get at those rusted screws I will almost certainly have to remove the stainless steel 'tray' that surrounds the work area. A pain as I didn't really want to delve in so far, and it's going to need sealing back to prevent leaks.

Meanwhile the runners are soaking in phosphoric acid (running short of citric !)

So how to drill out and re-tap these pesky screw  :scratch: Any suggestions welcome if they mean I don't have to remove the tray - distinct case of 'scope creep' here  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 29, 2014, 01:49:53 PM
The 'curtain rails' have cleaned up really well. It took quite some soaking, and scraping, and certain bits were so caked I had to sand blast them, but the result is more than acceptable. Quite surprising seeing what a state they were in  :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 30, 2014, 03:48:16 AM
So in the absence of any other ideas I took the bull by the horns and removed the 'tray' that surrounds the work area. 32 screws later it was off giving far better access to the rusted screws
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 30, 2014, 03:53:47 AM
Fortunately the rubber gaskets that seals the tray to the main base remained stuck firmly on the tray and came away cleanly with it. There is evidence of silicone sealant having been applied previously to this joint and I will probably do the same on re-assembly.

So the next job is to fabricate some sort of drill guiding jig to clamp on to avoid boo-boos.

However I have to stop now as I'm due to collect 'Robert the Boar' from Kent. 'Blossom the Sow' is hopefully coming in to season and needs covering to produce a litter that will be ready to wean in early spring.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 30, 2014, 10:36:28 AM
So Robert the Boar is now playing Piggy Back with Blossom and I can return to drilling out rusty screws !

The front screw had just the slightest bit still protruding, so I could use it to centre the jig. Jig comprised a bar, through drilled 5 mm (tapping size for 6 mm) and counter bored 5.8 mm to accept the short screw stub. This I clamped on and drilled through, and eventually it came out nice and concentric,as when I was re-tapping it I could feel I was following the original thread, just clearing it.

I started using my air drill, reasoning that it was more controllable in this confined space, but it didn't have enough umph and the mains electric was called in to help.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on September 30, 2014, 10:43:51 AM
Now the front screw was easy to centre using the jig. Nothing protruding on the rear one, so I had to use my 'Optical Centre Punch'. Not the easiest of places to use it, especially as I had to rig a torch to get enough light into it, but it worked ok

The previous screw had drilled out happily using ordinary HSS jobber drills - not this one. Even a brand new unused drill wouldn't touch it  :bugeye: I ended up taking a trip to our nearest 'tool shop' - really just imported Chinese stuff in the main, and getting a cobalt drill. Out of stock in 5 mm, ended up drilling through at 4.5 mm and then managed to clear the last 1/2 mm with an hss drill.

Again this hole tapped out nicely following the original threads, so a success, but what a palavour just for two rusty screws  :bugeye:

Now I know what I want for Christmas - a set of cobalt drills - went through like butter  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 01, 2014, 11:45:32 AM
A bits and pieces day today.

First I cleaned up and etch primered the 'drawing arm' that allows a replica of the part in the CNC memory to be drawn in pencil. Was going to 'satin black' it but my 'spare' can proved to be a dud  :bang: More on order.

Then I replaced the 'tray' that surrounds the work area, using ordinary sanitary caulking to seal it.

Then I made a replacement cover sleeve for the work arm - the original had corroded and looks as though rats have been nibbling it
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 01, 2014, 11:55:16 AM
I don't like sheet metal work at the best of times, and stainless steel is the pits ! My guillotine doesn't like cutting it, and it's quite difficult to get sharp bends in the folder, despite this only being 1 mm and supposedly annealed. Turned out ok in the end.

Then I set to making the longer holder for the wire pulley - this was needed not only as the original was corroded, but also as the pulley needed shifting to the right a bit to give adequate 'wrap' of the wire around the tungsten carbide contact. It should just have been a matter of cutting the 10 x 30 mm stainless 'flat stock' to size, and drilling and tapping a few holes. However the stock was so 'un-square' I ended up milling it on all sides to square it up.

The position of the pulley is rather arbitary based on the 'that looks about right' school of design - time will tell if it is !

Now I'm puzzling how the wire is supposed to be routed when the arm has the sliding seal that attaches the 'curtains' fitting round it. Time to search the web for picture  :scratch:  :coffee:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 02, 2014, 10:05:25 AM
So at last the slab of white Delrin arrived and I could make up the mounting for the tungsten carbide contact. What lovely stuff delrin is to machine - such a contrast to the stainless steel I've been working on !

Having roughly cut the slab to size on the band saw, and milled to final size I needed to spot through the existing machinable ceramic insulator to pick up the mounting hole centres. Then it was just a case of drilling and countersinking to finish that item.

Next on the list was the stubby axle that mounts the contact. Turned down from an old stainless pump shaft, axially tapped at one end 5 mm to mount it and 4 mm to take the screw that both holds it on and also takes the electrical connection. This was followed by a couple a thick washers to complete the assembly.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 02, 2014, 10:08:08 AM
In that last picture I've stretched a length of the edm wire round the pulley to show the way the new contact just rubs the wire.

So now I need to re-mount the arm temporarily so that I can take some measurements for the sliding seal arrangement.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 04, 2014, 03:23:17 PM
Having re-installed the arm, complete with the stainless steel cover that I made, it was immediately obvious that the cover wasn't long enough to make a seal for the full travel of the machine. I just slavishly copied what was there when I got it. Bad move as it's apparent now that this machine has been at some stage re-worked using bits from slightly different ones. Ah well - just bend up another one  :bang:

The black paint arrived today, so the drawing arm got another coat of paint
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 04, 2014, 03:25:25 PM
Tomorrows job is to fabricate the seal assembly, so when at last I get my hands on some usable bellows the machine can be put back in service
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 10:54:23 AM
Well after a bit of delay as other things 'got in the way' at last the seal assembly is made and installed.

Carved from solid 20 mm square stainless steel bar it's somewhat more substantial than the original but functionally equivalent. It's main job is to tether the free ends of the bellows so that 'the curtains stay closed' as the table moves about the projecting arm.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 10:59:57 AM
I had had to guess how much to make the seal material compress to be a decent sliding fit and yet not 'grab' on the arm cover. Having made it with 3 mm deep slots to take the seals I was erring on the cautious side, as I could easily relax the seal by sinking them deeper, but to compress them more without packing that would work loose would be a pain. As expected it was too tight and I had to sink the slots a further 3 mm to stop any tendency for them to 'roll' as it moved.

Here it is in place:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 11:04:45 AM
Now I have failed to source suitable bellows material, so have bitten the bullet and commissioned some to be made. There goes my pocket money for many a day  :bang:

At least they will be professionally made from the right material. Downside is that they are on a six week delivery. As I had one of the original bellows that was 'sort of ok' I decided to go ahead and re-assemble the machine using that one bellows - after all I've had it for several years with neither one working !

So first of all I had to re-thread the power cables and flushing water pipe through the arm, then having replaced the arm cover the seal and bellows etc could go on
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 11:28:48 AM
So the machine is back together and apparently working. I did a dry run on paper of a spline that I cut several years ago and it seems ok. However there are still a few little niggling things that I need to sort before this project is put to bed.

Firstly, when I tried the flushing water having got things back together, the machine made a big puddle of water  :bang: Now this is coming from under the main body of the machine, and there is very little plumbing in this bit - most is in the main water tank. It will be something trivial but I'll have to take off a few panels to see what. Basically, pressurised de-ionised water is fed to the two 'flow control valves' below the plotting table, and from there is routed to the upper and lower flushing nozzles. Water then drains out of the big casting that is the work support via a flexy pipe back to the tank.

Secondly, when the machine was delivered years ago, one of the two sliding guards that move around as the work table moves was missing. As they are supposed to be bolted together to form a rectangle with a large square hole in the middle, half of one isn't much use! So I never fitted them - I did however order up a sheet of 2 mm aluminium to make one. The machine body has a 'kerb' of 8 mm x 10 mm aluminium bar that catches on the lip of the covers and limits their motion. One had apparently been forcibly ripped off as it's remains were still attached - I've never made the covers as I didn't have the bar !!!! Bar stock on order  :thumbup:

Thirdly, the upper wire guide assembly racks up and down like the Z axis of a mill, the idea being to minimise wire length and water flushing distance for thinner work pieces. To this end the cooling and flushing pipes and power leads have sufficient free length to allow the downwards movement, but they flap about and get tangled in the polycarbonate anti-splash shields - so they need some form of re-routing or maybe just tidying up

Fourthly, having just re-threaded the wire I am even more convinced that the 'Vee Ditch' wire guides are the way to go, although it will need a bit of ingenuity to fit them and construct suitable flushing nozzles I'm sure it will be worth it!
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 12:21:50 PM
Well the list is getting ticked off one by one!

The leaking water WAS trivial I'm glad to say. Just a Jubilee clip that responded to a few more turns to tighten it  :ddb: It is one of two each side of the 'Conductivity Cell' with electrodes used to monitor the conductivity of the water.

Looking at the rust stains below this assembly, it has probably been dripping for quite some time  :bugeye:

There is one more thing though to add to the 'to do' list on this machine: Re-learn how to program it :coffee: The basic moving around is simple G code, but there are pages and pages of 'cutting conditions' that need referencing in code (and understanding !) It's a couple of years since I last did it so hopefully it'll all come back so long as the appropriate grey cells haven't died in the mean time  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: DMIOM on October 08, 2014, 01:55:42 PM
........Thirdly, the upper wire guide assembly racks up and down like the Z axis of a mill, the idea being to minimise wire length and water flushing distance for thinner work pieces. To this end the cooling and flushing pipes and power leads have sufficient free length to allow the downwards movement, but they flap about and get tangled in the polycarbonate anti-splash shields - so they need some form of re-routing or maybe just tidying up.....

Just watch how you re-route / tidy them! linky (http://gpsworld.com/improper-fuel-line-installation-led-to-incorrect-galileo-orbit/)

Dave
Title: Re: Titivating a Wire EDM Machine
Post by: Henning on October 08, 2014, 02:15:04 PM
........Thirdly, the upper wire guide assembly racks up and down like the Z axis of a mill, the idea being to minimise wire length and water flushing distance for thinner work pieces. To this end the cooling and flushing pipes and power leads have sufficient free length to allow the downwards movement, but they flap about and get tangled in the polycarbonate anti-splash shields - so they need some form of re-routing or maybe just tidying up.....

Just watch how you re-route / tidy them! linky (http://gpsworld.com/improper-fuel-line-installation-led-to-incorrect-galileo-orbit/)

Dave

Considering how Mr. Mawson seems able to make a tidy job of even the worst of basket case machines, I'd hazard a guess that if he'd been in charge the satelites would not only be in the right orbit, but they would have self repair system and also a system to get them into the right orbit should they not behave themselves  :beer:

Not many comments, and I guess it's because other people too are so impressed and at the same time feel so inadequate?

It's a stirling job again Mr. Mawson and i thoroughly enjoy following along, even if i have troubles understanding everything you do!   :mmr:
Title: Re: Titivating a Wire EDM Machine
Post by: Spurry on October 08, 2014, 02:30:12 PM
Not many comments, and I guess it's because other people too are so impressed and at the same time feel so inadequate?
It's a stirling job again Mr. Mawson and i thoroughly enjoy following along, even if i have troubles understanding everything you do!   :mmr:

Ain't that the truth!
Pete
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 08, 2014, 02:42:44 PM
Well thankee kindly chaps

"It's a stirling job again Mr. Mawson and i thoroughly enjoy following along, even if i have troubles understanding everything you do!   :mmr: "

Now you are assuming I understand what I'm doing - don't be too trusting  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 07:17:35 AM
So after a brief delay when I had to rescue a dropped screwdriver from the machines innards  :bang: :bang: (Must make that sliding cover !) I made a start on tidying up the wiring to the rear of the machine where it fouls the polycarbonate splash covers.

At some time a retrospective mod has been added to ventilate the 'biscuit tin' the the U & V servo mechanisms sit in. This box is suspended on the bottom of the 'Z ram' which is manually driven up and down. It comprises a wimpy under powered little fan remotely mounted in a box, and both the feed and return air is piped though 1/2" bore flexible piping that totals 2.2 metres in length. As you can imagine the air flow through this arrangement is microscopic though presumably it must have helped an over heating problem. The box that the fan is in, and it's adaptor on the back of 'the biscuit tin' is well engineered, but it's design is dreadful ! Also power to the fan (24v DC) is by two single core wires dangling all over the place and lead into the fan box through one of the air pipe holes - very crude. The side of the fan that you cannot see in the pictures butts up against a 'funnel' machined from some engineering plastic reducing it's orifice to 1/2" !!

The result of all this is that the 1/2" flexible pipes and fan feed wires were a mess - some re-engineering called for.

I removed the 'fan box' dismantled it, and put a cable gland in it's end plate suitable for a more conventionally covered cable to power it
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 07:33:06 AM
Now this description is slightly out of order, as to re-wire the fan the rear machine panel had to come off - but this had had to come off anyway, as I wanted to lose some of the drive cable back into the chamber. Although it would cheerfully slide back into it's gland I had no idea what it might foul, as I'd not been in there before. As it turned out there was room to pull the cable into the chamber, and rationalise the number of cable glands - blanking off two unused ones.

Then I put 'cable wrap' around the power and water feeds to make them into a cable form, put the rear panel back and secured the cable form and air pipes with 'P clips'. I've reduced the length of the air pipes and exposed cable lengths to a bare minimum, so that as the Z axis goes up and down the resulting loop of cable is as small as possible (to avoid hitting the splash guards)

It's not ideal - I did consider installing an 'Energy Chain' arrangement but that would not be easy - I'll see how it works for now.

...hey ho ... onwards and upwards .....
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 12:37:39 PM
This afternoon I cracked on with the sliding cover that is missing. Did I say I don't like sheet metalwork  :bang: Big wobbly bits that slice your fingers  :(

So I dug out the 1 x 2 metre sheet of 2mm aluminium that I bought perhaps two years ago for this job - those sucker things intended for glass work a treat handling sheets single handed. I had hoped that the cover would come out of a width of the sheet but no such luck - it has 8 mm upstands (or rather downstands in the attitude that it is used) and is 1 metre wide, so short by about  11 mm !

I cut the sheet approximately to size to give me an off cut that I could use to check bending allowance for this particular material on my particular bender. Turns out that each bend needs 5.5 mm ie the sheet needs to be 1 metre plus 11 mm for the pair of bends on the side, and the bend point needs to be 7.5 mm from the edge of the sheet for the upstand to be the correct height.

I made up a test piece aiming for 150 mm with an upstand at each end, and it worked out ok.

Then I did some test cuts on my corner notcher to get the edges to meet when folded.

Then I closed my eyes and went for it bending the three required upstands - when I opened them again it seems to have miraculously worked  :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 12:38:41 PM
Continues
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 12:45:05 PM
So now to cut out the rectangle in the middle. Jig saw, angle grinder panel saw or nibbler ?

Jig saws tend to make sheets leap up and down, angle grinders clog on aluminium, panel saw is a pain so the nibbler drew the short straw. Now I have to say this is not my favourite tool - whenever I use it it gives me grief and less than perfect results. To get anything like a straight line it needs to run down a guide, and clamping the guide generally prevents the working punch enter the cut. I suppose really I need a much wider guide that can be clamped well back from the cutting face.

I got there in the end with only a little wobbly bit at one end that wont show as its where the original cover clamps on to it
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 12:55:26 PM
Now conveniently, marking out the fixing holes is just a case of spotting through from the original cover. I did this, and was about to drill holes suitable for a Hank Bush as the sheet is only 2 mm thick. Then it dawned on me - nothing can project below the sheet, as it slides over the 8 mm high 10 mm wide 'kerb' that surrounds the hole in the machine. Anything sticking down below the under surface will foul on this kerb  :bang:

Curiously where the two halves of the cover join, there are four holes on each side. The outer two are counter sunk for apparently a 4 mm screw, and the inner two are drilled but not counter sunk.

So the quandary is how to bolt the two halves together without anything sticking out below. Theoretically I can tap the cover that I have made M4 and fix using M4 x 4 mm screws (do they make them so short?) but I have a feeling that M4 in only 2 mm of soft aluminium is going to have very little strength. Not sure that I have a choice unless you have any suggestions?

Going to sleep on it before I start tapping !
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on October 09, 2014, 02:45:55 PM
Could you drill holes in the right place on the kerb, so that captive nuts welded under the bottom guard sheet drop into the holes, thus laying flat, when the sheet is in the right place? The upper sheet then slides over the top, and 2x screws go into the captive nuts.

I presume the "kerb" moves with the machine/guard sheets?
Title: Re: Titivating a Wire EDM Machine
Post by: RussellT on October 09, 2014, 02:57:04 PM
Countersunk bolts from below?

Russell
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 09, 2014, 03:34:03 PM
Ade, no the 'kerb' is fixed to the body of the machine and catches the bent down edges of the covers as the table moves them around. It's a bit like a skirt round the table but as the rectangular hole in the pair of covers is bigger than the table support it doesn't move until that table motion passes a certain point. Hard to describe so I hope you get it.

Russell, yes I've been thinking along those lines, but the original cover is already countersunk from above on four of its eight holes so they must have originally screwed in from above. All very odd !

I suppose that there's not much to lose by trying tapping at 4 mm . I've found some M4 pan head x 4 mm screws on ebay - I'd prefer button head to keep the profile low but I'll probably go with them and see what happens.

Thanks to you both for the interest and suggestions
Title: Re: Titivating a Wire EDM Machine
Post by: RussellT on October 10, 2014, 03:59:43 AM
the original cover is already countersunk from above on four of its eight holes so they must have originally screwed in from above. All very odd !

It does seem odd - especially that only half the holes are countersunk.  It makes you wonder whether that's a mod - and perhaps someone discovered that it wouldn't work with a protruding screw - hence the missing guard?

If you're concerned about the threads in the aluminium perhaps you could loctite some studs into them so that they wouldn't wear - of course your plan always allows for the fallback position of contersinking from below.

Russell
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 05:13:45 AM
Well I went ahead and tapped the holes. Horrible in soft aluminium.

On assembly amusingly it became obvious that one of the 'inner' holes (ie nearest the table) actually isn't accessable in any position of the table to put a screw in  :scratch: (See picture 'Bottom-Left') Anyway I went ahead using some stock 6 mm pan head screws packed with washers so that they don't project below.

It basically works - I did have one nasty moment when moving the table about and it caught - one screw was sticking down ever so slightly - had that been on automatic programmed movement it would have torn the cover apart I suspect.

Here are some pictures showing the limits of travel to illustrate how the cover is pulled about over the base of the machine
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 05:17:30 AM
Now the cover rectangular hole is larger than the bit of the machine that pushes it about so there is deliberate 'lost motion' (or back lash if you like) - to illustrate this I've centred the table then show the cover able to slide a fair way back and forth - (same looseness is there side to side) :
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 05:23:01 AM
Now I don't think that this method of joining the two halves is a satisfactory design. Currently there is a single joggle allowing the original half cover to rise over my new one. It must have been the top element evidenced by the counter sunk holes in it.

However I believe that a 'double joggle' so that the top cover is offset 4 mm and the lower one by 2 mm allowing a 2 mm stainless steel strip to take the threads would be a far better design.

I'll see how she goes 'as is' as forming joggles accurately isn't something I've done before.

Crap-O-Cad drawings depicted below
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 10:42:47 AM
So what do you do if you've never joggled, haven't got a joggler, and want to joggle  :scratch:

Well you do a bit of googling  :coffee: then set to and make one - obvious really  :ddb:

I need to joggle about 8" wide in 2 mm aluminium plate and have a 2x material (ie 4 mm offset) on the joggle. Finding a 22" length of hot rolled bar I halved it, then milled suitable steps in it to form the offset. Really the corners should be rounded, especially if the bent component is stressed, but this isn't and I didn't  :ddb:

Then I drilled and tapped for a pair of 12 mm studs, so the joggler could be clamped in place while the (rather large) part is manoeuvred into place on the press.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 10:44:41 AM
Then we need to try it out. First a small offcut in the vice, and check the offset is correct
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 10:46:45 AM
OK that was painless - now we need to do a full width test - actually this bit is a bit wider than the cover bits that I need to joggle.

Too big for the vice I think so lets use the workshop press
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 10:48:18 AM
That was about 25 tons - probably a bit enthusiastic as the mill scale marks came through on the aluminium  :ddb:

Anyway it seemed to work ok
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 10:49:36 AM
So now I need to pluck up courage to do the actual bits on the cover, but first I need to convince myself that I can afford to lose the length from the cover that the joggle will gobble up - need to take some measurements
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 10, 2014, 12:11:58 PM
Tests & measurements completed here are the results.

Total loss of length having joggled a piece of 2 mm aluminium = 1.78 mm
Extra free movement available = about 5 or 6 mm - phew !

The length loss at 1.78 mm is far less than I'd expected - odd things happen when you bend sheet metal !

The cover slides in the  (say ) Y axis and is limited by its down turned flange coming against the 'kerb' on the machine base, the cover needs to be able to move for the full axis travel plus a bit of leeway - that is where the 5 or 6 mm comes from and to increase it would mean less overlap of the joggles - the joining holes are already drilled but one cover could easily have elongated slots if things are tight. I can imagine that the cover arrangement is not perfectly square so leeway may need to be increased.

Doing this exercise reminds me that one kerb is still missing - bar stock not yet arrived !
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 11, 2014, 06:49:18 AM
Unusual to have a metal delivery on a Saturday, but I'm glad to say the aluminium flat to make the missing 'kerb' arrived this morning in a torrential downpour.

Simple matter of cutting to length and accurately drilling and countersinking six 4 mm holes to match the exiting tapped holes in the machine - one of those 'easy' jobs that sometimes go horribly wrong, but today the gods were smiling down on me and it all fitted perfectly  :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 11, 2014, 09:10:33 AM
Well that was a very short lived feeling of satisfaction  :bang: :bang: :bang:

Investigating the cover joggle I moved the table to the sound of graunchings and this was what I found
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 11, 2014, 09:17:42 AM
The new kerb has been totally mangled in pretty much exactly the same way as the original was when I got it. But what is causing it  :scratch: :scratch:

Access is very difficult in the small gap between the upper stationary surface of the machine, and the lower moving surface of the table, but by using mirrors and a flexy light I found that one half of a shipping clamp was screwed to the table  :bang:

This is a short bit of angle iron, one web of which has been intent on removing that kerb when anyone fits it. Ah well at least now I know, and I can remake another kerb, but first I need to find a way to get at the shipping clamp to take it off. A very long allen key is called for. That angle web must have just cleared the machine upper surface.

.... off to order some more aluminium  :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: Pete W. on October 11, 2014, 11:15:10 AM
Hi there, Andrew,

I've been following this thread with interest.  I'm sorry to read that you've landed on 'a snake's head'!   :bang:   :bang:   :bang: 

Ref.: long Allen key - if we were neighbours, I'd offer my set of Allen stubs that fit a 1/2" socket set handle.  They're that old that they're probably Imperial but then the same is maybe true of your machine?

I'm sure that, somewhere in my bookcase, I've got a Davall Gears catalogue in which they say they use a CNC wire electrode erosion machine to make the moulds for their plastic gears, including correcting for the shrinkage as the plastic solidifies!  That's some precise correction in a 64 DP gear!!!!!!!!!!!!!!! 
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 11, 2014, 12:07:55 PM
Pete thanks.

In actuality it wasn't too bad getting the shipping clamp off as the cap screws were finger tight! Casting my mind back to when I got the machine in 2011 I'm having difficulty remembering who shifted and placed it. I think the chap who delivered it had been briefed on the clamps as the previous owner had fitted them and the shipper removed them, but it's entirely my fault for not checking. I remember putting the other ones in a plastic bag inside the machine for future use, so I'll add this one to that !

I have successfully cut gears with this machine, and also internal splines in gears. I generate them in a dedicated utility and save as a .dxf, then import it into FeatureCAM to generate the G Code as FeatureCAM amazingly 'knows' this machine and generates appropriate code. For instance it allows for keeping a 'tab' on the gear to keep it fixed to the stock, and then generates a stop, allowing me to place a magnet to hold it in place, then I can restart the machine for it to finish the cut. Remember that the cutting force is negligible, its the weight of the part that would make it sag without the magnet.

When I've re-calibrated it after its 'pulling apart' (at least the wire verticality will need re-setting) I'll see if I can cut a gear in something pretty hard such as tool steel, just as a test piece.

I've always intended to cut plain carbide indexable inserts into things like Acme thread profiles just for the fun of it but never got round to it.

Your comment about gear moulds and shrinkage: The machine has an inbuilt function allowing the part described in G code in memory to be scaled over a huge range, both increasing and decreasing, and to several decimal places. So shrinkage allowance would be dead easy.

(Incidentally this is a 1984 machine and everything is metric)
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 12, 2014, 07:27:57 AM
Having made the joggler, that works splendidly, I've decided to jump another way  :ddb: I wasn't happy with the extra height created, as it would leave barely 2 mm clearance above to to the machine table.

So on the suggestion of a member of the MIG Welding Forum, I've been experimenting pressing nuts into the thickness of the 2 mm aluminium sheet to make a re-inforced thread, and it seems to work really well
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 12, 2014, 07:31:04 AM
On the actual cover I will use half nuts pressed from below to leave a ledge for strength - that was a full nut that started as 3 mm thick but got squashed to 2.3 mm > Needless to say I had to re-thread it !

I will need some M4 x 4 mm csk screws that I cannot find commercially so I shortened some 6 mm ones using a springy clamp made from two bits of 1 mm stainless and an angle grinder !
Title: Re: Titivating a Wire EDM Machine
Post by: Manxmodder on October 12, 2014, 07:58:46 AM
Hi Andrew, this is a very interesting project. Something I have wondered about EDM machines is how much wire do they use during cutting and how expensive is replacement wire?......OZ.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 12, 2014, 08:35:20 AM
Well Oz, I got this machine in 2011 and I'm still on the original 8 kg roll :ddb:

But in all honesty that's no real judge as  it's not been used much. I've bought various reels as they turn up on eBay but now I have quite a stock so am rather discerning on what I pay now - for instance one sold on ebay for £23 the other day, but with postage at £15 £38 was more than I was prepared to pay. I think it is not much more than that from a dealer.

***(later edit ... I'm wrong it's £115 plus VAT for 8 kgs  and it has 2400 metres on it :bugeye: )***

There is a heck of a lot of 0.25 mm brass wire on an 8 kg spool - I've also got several 16 kg ones  :bugeye:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 15, 2014, 04:29:50 AM
At long last I think I've sorted the sliding cover fixing.

The pressed in nuts seem to work a treat, and I ended up pressing in 'half nuts' which in M4 measured 2.09 mm thick - pretty well ideal for the 2 mm sheet that I'm working with. It was a bit of a fiddle balancing the cover on the press but I got there in the end.

With my truncated screws there is no projecting below the panel - so hopefully jamming will be a thing of the past.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 15, 2014, 07:08:52 AM
Replacement 10 x 8 mm aluminium bar arrived today so at last I've re-made that mangled kerb, and re-fitted the sliding covers. They seems to slide nicely with no bits catching this time (fingers crossed) - I've been up to the axis limits in all directions.

It's taken a while for two reasons - firstly deciding on the cover joining method and experimenting with it, and secondly waiting for the bar stock and stainless M4 half nuts to arrive. Covers will have to come back off in a few weeks for painting, but I'll treat that as a separate job as several panels need painting.

Meanwhile I've been refreshing my memory uploading and downloading code to the machine from a PC. As I have three CNC machines and the PC only has one serial port I use a switch box to switch the RS232 source - simple enough - but when I came to set up my DNC software (NClite V7) it insists on each CNC machine having a different COM port number  :bang: I could expand the number of COM ports using a USB adaptor but don't really want the timing issues that that may introduce. Awaiting response to my query from India where NClite is written  :bugeye:
Title: Re: Titivating a Wire EDM Machine
Post by: stvy on October 17, 2014, 02:12:44 PM
Andrew,

Am enjoying this thread..... I have to admit I really like these re-build threads with these "above garden shed sized" machines.

One thing that this thread got me wondering is if this machine is the perfect tool to make a block of blank multifix tool holders..... Do you have a project in mind for it?

Steve
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 17, 2014, 02:53:31 PM
Steve,

There is no definite object in mind. Today I've been doodling various gear profiles, just as a test piece. I'm loathe to start using it with water until I've finished one or two cosmetic changes. Several years ago I bent up replacements for several of the panels that were missing. Having now sorted that sliding cover it's time the tin work got a coat of paint ! I ordered up a RAL colour chart, and now it's arrived went to trying to match the grey it's mainly painted, but various bits are different greys  :bang: I brought in the heavy guns and got the wife to decide (RAL 7044 silk grey) and placed a paint order today. It all needs etch primer as most is galvanised sheet with some aluminium.

I've been spending my time trying to sort out my 'DNC' issues - DNC refers to the coupling of the machine to a PC via (usually) RS232.

Firstly physically: up until now I've have cables trailing over the floor - I've installed conduit uprights to take the cable up into the gods and thence wired back to my desk avoiding walk ways.

Secondly software wise. I have three CNC machines and was hoping to use a single serial port on the PC via a switch box. However the DNC software, which holds configurations for each machine (which have widely different configs) insists that each have a separate COM port number.

Rather unwillingly, as the software vendors are not answering queries, I've bought a 'USB to four Serial Port' adaptor 'Hydra Cable'. Installing it proved a nightmare with ports ending up with silly numbers. I solved that (hidden previously installed USB things needed purging) only to find that it's operation was inconsistent to say the least, with ports sometimes working and other times not.

http://www.ebay.co.uk/itm/330820909340?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The 'Hydra Cable' is on it's way back to the supplier and a (hopefully) more professional version ordered:

http://www.ebay.co.uk/itm/361060354571?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Time only will tell  :bugeye:

Back to your question - Yes I'm sure that the profile of a Multifix holder could be cut relatively easily - It would be a very slow way of doing it - presumably they only need to be EN8 or some such decent engineering steel that could be cut on a CNC mill. Now if you needed it in tool steel in the hardened state it would be a good choice
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on October 18, 2014, 05:49:10 AM
Multiple COM ports always were a nightmare on PCs. COM1-4 were typically available in the BIOS, but COM1 & 3, and 2& 4 used to share interrupts, so realistically you could only reliably use 2 at a time anyway...

It _used_ to be possible to buy add-on cards with additional COM ports attached (with their own interrupts & memory addresses), but try find one that goes in a modern PCIe slot. Assuming you've even got a computer with a PCIe slot these days - most laptops certainly don't have room for such things.

Q: Wouldn't you be better off running 3 salvaged laptops (=cheap on fleabay), and a KVM splitter? That's what I'd do. If you want a KVM splitter, I've got an 8-port PS/2/VGA one I no longer use going begging. Good quality Adder one too.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 06:01:18 AM
Ade,

I'd initially intended to have a small form factor Compac (as I have a pile of them!) at each CNC machine, and whiz files around by Ethernet only using RS232 for the final link to the machine - but it's a space issue at the machines, so I decided to concentrate everything on one desk top (another HP / Compac SFF) actually at my desk.

We'll see how the replacement USB -> 4 x serial works  :med:
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on October 18, 2014, 06:10:07 AM
What expansion port(s) do you have in those SFF machines? If they'll take PCI cards, you can fit one (or two) of these: http://www.ebay.co.uk/itm/261083309079

And then you've got 4-6 serial ports (including the 2 on the machine)....
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 06:12:04 AM
This mornings job was to refresh my memory as to how the two wire guides are set to be vertical. Fortunately the book of words 'sort of' covers it - however their procedure only covers one axis (which they don't point out) so it needs repeating with the jig (see later) in two places.

However firstly I had to re-thread the wire - it's always been a pain to thread but today I developed a couple of techniques that do help somewhat.

Firstly, to get the wire through the sliding seals without concertinering it into a zig zag I used a length of thin nylon tube. Slide wire down tube, poke tube through seal into working area of machine, pull off tube. Simple and easy.

Secondly getting a 0.25 mm wire threaded into a hole in a sapphire that is only microns bigger - it's fun! However if instead of cutting the wire with (very sharp) cutters, you break it. It must neck down before snapping and produce a tapered end that threads in far more easily . :ddb:  It does however dig into your fingers somewhat ! I presume that cutters must actually distort the wire into a chisel shape that flares a bit at the edges.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 06:20:05 AM
Now fortunately my machine came with the 'verticality jig' so it was just a case of (once that bally wire was threaded) plonking the jig onto the holding frame, adjusting the X & Y position so that the wire glances the jig, then tweaking U & V to get the same degree of light flickering on the top lamp as is displayed on the lower one. Once this is done, the U & V co-ordinates are used as offsets internally so that this position is regarded as zero for them and the wire is vertical.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 09:54:04 AM
So of course in my excitement at getting close to finishing I broke my good resolution not to water it up before painting - had to try it out !

So as I type this it is cutting out a 20 mm square in a bit of 1/4" mild steel hot rolled plate just as a test. It's so far cut a length of 23 mm in 15 minutes - nothing optimised so far - just playing.

It's not the most photogenic process - the covers and water gets in the way but here are a couple of pictures - the first through the covers, and the second with the splash covers off (briefly). Not the best but hard to get in there to take them !
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 11:26:07 AM
So 82 minutes after starting the cut we have cut 85 mm of cut length, and amazingly the part has come out pretty well bang on target size  :ddb:

No doubt cutting speed can be increased by tweaking, but by contrast with how it was before I retro-fitted the lower wire contact it's quite fast. I previously had to slow it down to avoid wire breaks - this time none  :thumbup: For the same thickness material (1/4" it would have cut pretty much the same rate independent of how hard it was.

Note the use of a rare earth magnet to stop the cut off part sagging and fouling the wire as the cut finished. Amazing amount of debris produced from a small cut. It's mostly very fine steel particles, but there will be brass from the wire mixed in. I may experiment with a magnetic particle separator to save the main filter some work.

I need now to get some time in playing with it to learn to use it 'comfortably' rather than always being on the edge of my seat !
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 18, 2014, 04:43:59 PM
What expansion port(s) do you have in those SFF machines? If they'll take PCI cards, you can fit one (or two) of these: http://www.ebay.co.uk/itm/261083309079

And then you've got 4-6 serial ports (including the 2 on the machine)....

I'll certainly explore that suggestion Ade - thanks
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 20, 2014, 04:01:44 AM
Yesterday, just to get some machining experience on the EDM, I set it cutting out a pair of 18 tooth 1.5 MOD gears from 1/4" mild steel plate. The gear profile was defined in FeatureCAM and down loaded to the Fanuc as G code.

Came out bang on as per the defined gear  (which I should have given a bit more tip radius to !) but it makes what you tell it to make  :ddb:

Today's exercise is to get my head around optimising the cutting conditions to speed the process up. Those gears took best part of four hours EACH so not an ecconomic way unless it's in something very hard or is an exotic tooth profile. (Those gears have a cut length of 184.6 mm and took 3 hours 45 minutes and 26 seconds each)
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 20, 2014, 06:00:28 AM
So first results of tweaking: That 20 mm square a few pictures above now cuts in 47 minutes as opposed to 85 previously, so almost halved cutting time. Don't yet understand all the parameters . . .but I aim to  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: Kjelle on October 20, 2014, 06:45:29 AM
Weellll... This has been a rather captivating story so far...  :mmr:

Kjelle
Title: Re: Titivating a Wire EDM Machine
Post by: Pete W. on October 20, 2014, 07:42:16 AM
Hi there, Andrew,

I think those gears are impressive.    :clap:   :clap:   :clap:   :clap:   :clap:   :clap: 

3 hours, 45 minutes and 26 seconds is a far shorter time than you'd wait for the Postman if you bought them from 'outside', especially if your time of need was 17:00 on a Friday evening!

Here's a question, though, which machine/process would you use to make the central bores and how would you register with the gear-tooth PCD? 
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 20, 2014, 08:12:05 AM
Thanks chaps - I must admit to a certain self satisfaction at the results! It's also nice to see some people are actually reading this drivel.  :scratch:


Pete, If I was doing it 'properly' I would have drilled a hole, then threaded the wire through it and got the machine to 'find the centre'. Then I'd have cut the bore accurately on the machine, then cut the wire, move to the outside, re threaded the wire and cut the gear. It would then have been accurately centered. But you know the threading issues.
Title: Re: Titivating a Wire EDM Machine
Post by: Spurry on October 20, 2014, 08:29:38 AM
Thanks chaps - I must admit to a certain self satisfaction at the results! It's also nice to see some people are actually reading this drivel.  :scratch:
Andrew
You are too modest. A brilliant thread, very well written and photographed. Keep up the good work..........pleeease.
Pete
Title: Re: Titivating a Wire EDM Machine
Post by: spuddevans on October 20, 2014, 01:27:32 PM
I've been watching too, and very impressed with your efforts and results.  :thumbup: :thumbup: :thumbup:

Tim
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 20, 2014, 01:36:57 PM
Thanks for the comments Pete & Tim.

I decided that I have to get to grips with the wire threading issue. It breaks down into two areas:

a/ The lower guide is in a confoundedly hard place to look at

b/ I'm trying to thread a 0.25 (and possibly burred in cutting) wire through a hole that is allegedly 0.255 mm diameter

Now there's not much that I can do about a/ (I think most modern machines run their wire downwards which would help) but I did a bit of research and asked a few questions on a professional forum about the actual wire and it's cutting. Apparently in early Elox machine manuals they advocated heating the wire with a cigarette lighter, and stretching it to break. Another manufacturer embodied a pair of  pillars with a voltage between them - stretch the wire across, anneal it and stretch to breaking point.

I tried the cigarette lighter method - it works and produces a thinned wire, but I'm not a smoker and the lighter is hard to manipulate as the wire is held taut enough to break. Strangely I'd thought of the electrical method independently so I thought that I'd do an experiment.

Digging out a 12v transformer, I rigged a pair of screwdrivers in my vice, holding them with non conducting soft jaws. Drivers about 3 1/2" apart, 12v on the wire - touch it on and POP  :zap: instantly the wire melts - volts too high.

So out came the ancient variac that I keep for scaring Health and Safety people  :ddb: A bit of experimenting came up with 3 volts being enough to anneal the wire. Takes a certain technique to take it off before it breaks, as if it fuses rather than breaks it forms a ball on the end.

Anyway from this crude test I've shown that I can taper the wire from it's original 0.25 mm to 0.13 mm - half it's thickness. It is possibly worth making up a little fully insulated box with a couple of pillars poking out, that I can use to stretch wire ends. (or I could stick with a lighter!)
Title: Re: Titivating a Wire EDM Machine
Post by: dawesy on October 20, 2014, 02:06:50 PM
Excellent project Andrew.
Really enjoying reading it so far even if I don't fully understand some bits (I'm still a newbie :D )
Title: Re: Titivating a Wire EDM Machine
Post by: dsquire on October 20, 2014, 04:52:26 PM
Andrew

It is allways a pleasure to read your posts and watch as you prepare retired machines for a come back. You do have the ability to get the best out of these tired old machines. I am looking forward to seeing what you will be cutting with this when you have it completed..

Thanks for sharing with us Andrew.  :D :D 

Cheers  :beer:

Don
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 21, 2014, 03:17:08 PM
I spent today running hard wiring up in the gods from my three cnc machines back to my desk in the workshop. The replacement USB to 4 x COM port box arrived by post this morning and seems much more stable than the one that I returned (for which the paypal refund came in this morning  :thumbup:) The thermo-plastic that they are making Sub D connectors from these days seems pretty poor quality. If you solder a male 25 way up the stuff melts so much that the pins point in all directions - had to plug the male into a female to keep them straight. I've been soldering these things for the past 45 years and not had this issue before  :bang:

Then fighting a loosing battle trying to find a suitable DNC program to link them up. CADEM make what seems the most appropriate, but they are still failing to return contact - probably don't want any more customers  :bang:

Tomorrow brings filling pot holes in the drive with concrete so probably not much will get done then  :(
Title: Re: Titivating a Wire EDM Machine
Post by: dawesy on October 23, 2014, 03:54:06 AM
Think everything is made by accountants and not engineers now Andrew. Good idea for keeping the pins straight though. I'll remember that one ;
I never understand companies that don't respond to customer questions. Had similar from pace radiators recently. The replied asking for sizes ( which were in the first mail ) I replied with a diagram but had nothing since.
Hope you get it sorted.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 24, 2014, 09:25:26 AM
Time to start slapping some paint around  :bugeye:

I've had to make several panels which were never painted, and the previous owner has made a hash of a brush finish on most of the original paintwork. Now my RAL 7044 silk grey paint and etch primer has arrived it's time to get on with it.

Weather forecast is predicting a dry week end, even if it is raining as I write this. So hopefully I can glass blast the old paint off tomorrow and start spraying. I doubt it will be fine enough for outside painting. So I started this morning clearing out the welding shop to hopefully give me enough space to blow some primer on as soon as the panels are de-painted. Glad I put all the machines in there on wheels  :ddb:

Next job was to remove the panels - the machine looked decidedly naked without them !
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 24, 2014, 09:31:50 AM
There are a total of ten panels needing cleaning and painting, ranging from large and heavy down to quite small.

I would really like to be able to strip the paint on the remaining horizontal surface surrounding the table as that too has been badly brush painted. If I could find a satisfactory way of stripping it I'd roller paint it to avoid over spray all over the work shop.

If only the original Nitromors stripper was still available it would do it easily, but the EU have banned all the good stuff in it that actually works  :(

Any suggestions for stripping selectively without throwing stuff all round the workshop would be appreciated.
Title: Re: Titivating a Wire EDM Machine
Post by: nrml on October 24, 2014, 03:44:15 PM
Can I suggest trying screwfix's ''No nonsense paint stripper'' along with a tungsten carbide bladed paint scraper. The combination has worked very well for me. You need two thick coats of paint stripper left on for an hour each (as per the directions) before scraping. It seems to be the only paint stripper that actually does what it says on the tin and it costs only £3.20, so you don't really lose much if it doesn't work for you.

BTW Thank you for all the excellent threads you have posted. They have all been most interesting.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 25, 2014, 10:20:50 AM
Thanks for the comments NRML

I've managed to locate some stripper with Dimethyl-chloride as it's base, and that is expected on Tuesday. Meanwhile this morning I succeeded in glass blasting all the panels that needed stripping, and got a coat of etch primer on them outside as the weather stayed fine.

No pictures as my iPhone decided it's battery was flat despite telling me it was 100% only two hours before - nothing to do with 'upgrading' to ios 8.1 yesterday I'm sure  :scratch:

One of the panels that I made a few years back, the one with a rectangular tunnel in it to give access to the water flow gauges, I had given a coat of primer to back then from a rattle can. Forgot that and sprayed it with  my etch primer and of course it reacted and gave crows feet every where. Ended up using paint stripper (B&Q ultra safe ultra useless) which as it was only fresh came off ok'sh . Re-sprayed and it along with the other nine panels will get a coat of  semi gloss tomorrow.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 26, 2014, 06:25:24 AM
So today I got a coat of top coat on both sides of all the panels and two on the outsides. If you look at the first picture and see the nettle bed behind the panels you'll see we had an early frost - no actually it's fine glass grit from the blasting yesterday. First rain'll wash it off.

Oddly the 'grey' etch primer is distinctly green :scratch:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 26, 2014, 11:42:41 AM
With rain threatening, and the paint having hardened significantly I decided to bring all the panels indoors to fully harden off for a few days whilst I attacked the main carcass of the machine.

I'm waiting for some decent paint stripper to arrive, but I thought I'd see what a hot air gun could do on those bits where it's safe to do so. Painfully slow  :bang: The metal takes the heat away too soon. So I brought out Big Bertha the Blow Lamp. Now it's not appropriate to use this everywhere due to the proximity of wires etc, but a lot of the surface area can be cleared. It worked a treat. Took about 20 minutes to do the bit that you see in the picture. The horizontal surface was far easier than the vertical, and I'm sure it's that over the years water got under the original paint as it just stood there - it looks a bit rusty - probably cleaned up somewhat when the previous owner brush painted it. It'll need a bit of rubbing down and primering but it's quite pleasing progress.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 27, 2014, 12:58:21 PM
This morning I managed to finish stripping off the vast majority of the paint on the machine carcass horizontal surface using the blow lamp. Still to remove the 'kerbs' to allow me to strip up to the edges. Still to use chemical stripper on some fiddly bits and also the edge of the work area 'tray', which is stainless steel, so if it cleans up ok I won't paint it.

The surface has obviously previously been stripped back where the rust shows but needs quite a bit of preparation prior to painting. I may risk a 'strip and clean' disk now 99% of the material has been removed as hopefully it won't make too much mess with the little that remains.

I remembered that yonks ago I had bought a 'touch up' spray gun for a project that never happened, and I've never used it. I'm going to experiment and see if it is feasible to use it without stuff going every where as a sprayed finish is very much preferable to a rollered one.

Then it was time to go to town and sort my iPhone 4S out. Upgrading to ios 8.1 had resulted in it's wifi refusing to work even after a 'factory reset'  :bang: After much faffing about I now have an iPhone 6 - an exasperating experience
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 28, 2014, 11:14:26 AM
Today I made a great discovery  :ddb:

I had thought that the top that I've been stripping was part of a welded structure forming the machine carcass. As I was working out how to fix masking for spraying, I got to wondering how the heck they put the machine together in the first place :scratch: Surely it MUST have been built from the bottom up ? The top MUST come off. Sure enough I found 8 concealed screws.

Huge benefit in that being able to remove the top meant no masking, and I could glass blast it to get it decently clean. Down side was that quite a bit else had to come off. The 'curtain tracks', the arm, and the work tray. Actually only took 20 minutes as I've had them all off before.

Net result is I've been able to properly clean up the metal work (including a 'water inlet panel' that I'd passed over last time.)
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 28, 2014, 11:17:49 AM
All this of course is a distinct case of ''scope creep  :ddb: ''

So today was a blasting spraying sort of day. Wind a bit too breezy but I think I've got away with it.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 30, 2014, 06:44:45 AM
So now it's all back together and looking slick in it's new coat of paint  :ddb: A bit of touching up needed in places, mainly as I got a reaction between the paint and the blue workshop paper towels that I used to separate the panels as they were fully hardening.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on October 30, 2014, 06:59:17 AM
I do have one issue to sort - if you look closely in the last picture you can see that the sliding covers that I had all the trouble joining together have warped. The original one was slightly curved but the one I made was nice and flat. Foolishly I decided to lightly glass blast them to get the finish texture on both to be the same. They warped all over the place and despite my best efforts I cannot get them to lay sufficiently flat not to rub on various bits of the machine. The easiest solution is to make another pair and that is what I've decided to do. But this time they'll get sprayed 'as is'  :ddb:

Now it's back together and offers the prospect of being used in earnest I decided to attack the wire threading issue head on. Two issues - visibility and tapering the wire end.

The first issue is that you cannot see the 'funnel' that you are aiming the end of the wire at from underneath the arm assembly. OK a 6" mirror tile with three 'feet' super glued on the back to keep it out of the water makes a significant improvement.

The second issue is that the wire is only microns smaller than the guide hole and needs tapering as discussed before. I opted for the Zippo lighter approach as it can be free standing when lit leaving both hands free to manipulate the wire. Light up, anneal the wire, and stretch to break - works a treat. I used to have a Zippo years back but needless to say couldn't find it anywhere. Ebay provided me one very cheaply and it came with FREE ENGRAVING. Had to put some poser text on it naturally  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 04, 2014, 05:59:29 AM
At the week end I managed to bend up the replacement sliding covers, but this time they DIDN'T get glass blasted before painting, which was what distorted them last time  :bang:

I took the opportunity to slightly redesign them. The stationary  'kerbs' that restrict their movement are 8 mm deep. The covers slide on top of these kerbs and have a down turned flange that stops them passing the kerb. The originals had 8 mm down turns, which meant that not only were they resting on the kerb, but also the top of the machine and scratching the paint when they moved. I have reduced the down turn to 5.5 mm giving a theoretical 2.5 mm clearance over the top of the machine if everything is flat and true. So now (again theoretically) the covers only touch the kerbs and not the machine top. In practice so far it seems to work ok. Pity I didn't remember to re-set my corner notcher for the reduced flange - if you look at the first picture you can see the corner is more 'open' than is ideal, but never mind eh ! My 'joggler' that I made earlier came into play joggling the join between covers and worked well. I had made it originally for a 4 mm 'double joggle', but inserting strips of 2 mm aluminium on each side reduced the joggle to 2 mm very satisfactorily.

Second picture shows the slight clearance I have created between the cover and the machine top.

Perhaps now I can get down to it and start using the machine in earnest  :scratch:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 04, 2014, 03:55:38 PM
This evening I managed to tick off another 'round-tuit' : The machine came with a 'remote pendant' - basically a box of switches and lamps on an umbilical cord replicating the axis motion buttons. But as my machine was originally equipped for automatic wire threading this particular pendant abounded with a load of extra buttons and lamps relating to features no longer on the machine. The pendant had had quite a bit of its controls removed already when I got it. Presumably this happened when when the machine had automatic function removed. I also robbed some apparently redundant buttons to get the main console functional, in some cases having to make frankenmonster switches from several others  :bugeye: I did at the time blank the few holes I created with grommets.

All this looked a mess, and as I now knew which functions were needed and which were redundant, having a picture of the simple control in the Operators Manual, I decided to do a 'proper job' and finish the task.

Only a case of removing surplus controls and making the wires safe with heat shrink sleeving. Amazingly as obtained there were loads of wires with bare ends just floating about. Probably their other ends are disconnected - but are they  :scratch: Not good practice to leave them bare even if they are isolated elsewhere.

The pendant is quite handy when moving the table to place the wire close to the work using the Mk1 Eyeball method.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 05, 2014, 11:26:33 AM
More playing about today. Really this is for PeteW who asked a few posts ago how I would accurately put centre holes in those 20 tooth gears that I cut earlier. I'd been playing with gear parameters in the FeatureCAM gear generating program, as I'd not been happy with the tip radius that I'd cut last time. So I generated a 25 tooth Mod 1.5 gear with what I hope to be the correct geometry, and to demonstrate the method this time put a 10 mm shaft bore and a 3 mm keyway - all cut on the EDM machine.

A/ Having downloaded the G code to the machine I mounted the 1/4" mild steel plate in which I had drilled a 3.3 mm centre hole.

B/ Then I cut the wire and threaded it though this hole.

C/ Then using an inbuilt machine function accurately located the centre of this hole and set it as X=0 Y=0

D/ Next I inserted an M01 (Optional Stop) command between the G code cutting the bore and the rest that does the actual gear teeth.

E/ Then I set the machine running with the 'Optional Stop' button pressed. (*)

F/ This cut the bore and keyway then automatically stopped waiting for my attention.

G/ Next I cut the wire, moved the table so that the re-threaded wire was outside the blank, and set it going

H/ Several hours later I removed the gear and cleaned it up.


(*) it was at this point I realised the the button was incorrectly labelled 'Option Skip' not 'Option Stop' as it should have been, so while it was making the gear I printed out another button label on overhead projection film and fitted it.

Mild steel always comes out with light surface rust, which I usually take off with phosphoric acid - this time I used the wire wheel.
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on November 05, 2014, 11:55:48 AM
Tidy!

How long is "several hours", and - when used in its original production environment - would the operator have been pushing the machine along faster?

What's the maximum thickness steel it'll cut?

Cheers!
Ade.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 05, 2014, 12:01:21 PM
Ade that took about 3 hours, but I know it wasn't optimised. Approximately 1 mm of cut per minute as it was set up. Theoretically it should do up to about 10 mm per minute on that 1/4" plate for a roughing cut.

It will however do up to 200 mm thick tool steel  :clap:
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on November 05, 2014, 12:10:04 PM
Thats quite impressive - especially if it can maintain its 20mm/min speed in that 200mm steel....

What about ali, brass, etc.? All cuttable? I may have to start watching eBay again....
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 05, 2014, 12:22:58 PM
If it conducts electricity it'll cut it. Speed will reduce with increased thickness - think in terms of 'area cut per minute'. They don't often turn up on ebay.
Title: Re: Titivating a Wire EDM Machine
Post by: AdeV on November 05, 2014, 01:38:27 PM
If it conducts electricity it'll cut it. Speed will reduce with increased thickness - think in terms of 'area cut per minute'. They don't often turn up on ebay.

I'd be interested to see what it makes of graphite.... or diamond. If you could cut perfectly sized dead-nuts parallel graphite cylinders, you'd be mates for life for anyone building a Stirling engine...!

eBay is a code for eBay, Apex, Riley Surface World (yes, that's a real company), Peaker Pattinson, and a few others...
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 05, 2014, 05:58:37 PM
One of its main applications is to cut copper and graphite as electrodes for 'sinker' EDM machines, I have reams of tables of cutting 'conditions' for graphite  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 06, 2014, 07:23:27 AM
An advantage of a machine that plods on doing it's own thing is that you can get on with other things while it does :ddb:

Before I set the machine cutting another test this morning I removed its 'running hours' meter, which has been rather flaky in operation. So while it ploughed it's own furrow I dismantled it to try and find the cause.

It's a mechanical Omron 'Time Counter' model KTH-R running off 110v AC - I'd already identified an LCD possible replacement at a very modest price if it wasn't fixable but better to fix if possible. Construction is a simple plastic jacket surrounding the metal interior works, that is sprung over a couple of dimples to retain it. Pulling it apart it was pretty obvious what the issue was - the original lubrication on the gear train was very stiff and solid. Rigging a 110v supply to it, it only took a gentle spray of WD40 to loosen up the solid grease to a more suitable consistency for it to start working freely. A bit of a clean up and re-assembly, and as I type this it's been running for over an hour with no problems. It can be popped back in the machine when its finished it's current job.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 11, 2014, 12:59:33 PM
At long last the bespoke bellows that I commissioned have arrived - in fairness slightly earlier than the six weeks I was quoted.

So they got fitted this afternoon - hopefully I won't now have to leave a folded towel down the side of the machine where they were missing  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: spuddevans on November 13, 2014, 07:52:16 AM
Looking very smart there Andrew  :thumbup: :thumbup:


Tim
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 13, 2014, 09:05:16 AM
Thanks Tim, it certainly is a bit prettier than when I got it, AND it now works  :ddb:

Still loads to learn about the nuances of the programming - quite a bit of subtlety involved to get a decent rate of cutting without breaking the wire.

I scored an ebay triumph for it the other day - nine 8 kg rolls of the brass wire - 72 kgs of wire - should out last me even at my current enthusiastic rate of use
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 14, 2014, 06:13:03 AM
Been cogitating on the power this machine consumes - the book of words says that it needs a 7kW three phase supply, and if it genuinely is pulling 7kW all the time it's running, at 14 pence per unit that soon mounts up. So I thought that I'd measure it.

Although I have a 'spare' three phase certified meter sitting on the shelf, it's not the easiest thing to lash up temporarily, as it has to be mounted so that the back is vertical. I fixed up my 'Owl' 'Intelligent Wireless Energy Monitor', using three current transformers feeding it's transmitter - one on each phase. For current monitoring and test purposes I have a 16 amp 'commando' plug wired to a cable mounted socket using 4 mm 'singles' cable that allow the current transformers to clip on to them.

Firing up the machine it was interesting to monitor it. On the back of the cabinet there is an isolator, which if turned 'on' feeds power to a three phase transformer in the de-ioniser unit, as well as to the main unit, but the main unit only powers up when the 'On' button is pressed. It's quite easy to forget the isolator and just press the 'Off' button on the machine - turns out that that transformer is drawing 150 watts just idling and not powering anything  :bugeye: Must remember to isolate!

Anyway the power with everything running is less than 3 kW so not as bad as I had feared - but still about £0.37 per hour just for electricity !
Title: Re: Titivating a Wire EDM Machine
Post by: millwright on November 14, 2014, 06:09:37 PM
So cutting that gear cost you £1.11p in elecricity, not taking your time and material cost into account or other workshop costs (lighting, heating and air). I dont think thats bad at all. Good job theres no charge for all the time you have spent getting it back on line.
i have enjoyed the log with all its trials and tribulations. what you have achieved is a bit beyond me but has been good to follow, as was the Traub lathe.  :clap: :clap: :clap: hope they can pay for their keep now.

John
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 14, 2014, 06:20:44 PM
Thanks for the kind words John.

No way will they ever earn their keep (other than in enjoyment) as I refuse to take paying jobs. I retired to leave that sort of stress behind. No problem helping friends out, but as soon as it becomes commercial obligations come with it. The previous owner of the Fanuc Tapecut wanted me to do some work for him and his customers, but I've refused for these reasons.

I do these machines for the enjoyment that they give me with their challenges. Pig headedness really, as if someone says something can't be fixed I rise to it!
Title: Re: Titivating a Wire EDM Machine
Post by: Will_D on November 19, 2014, 06:23:51 PM
And "TG" for people like you!
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 19, 2014, 06:27:04 PM
And "TG" for people like you!

 :scratch:  :scratch: :scratch:
Title: Re: Titivating a Wire EDM Machine
Post by: DavidA on November 19, 2014, 07:16:56 PM
TG = Thank God.

I think.

Dave.
Title: Re: Titivating a Wire EDM Machine
Post by: dsquire on November 19, 2014, 07:36:17 PM
And "TG" for people like you!

 :scratch:  :scratch: :scratch:

TG stands for Thank God. I fully agree with Will. The journey is sometimes much more enjoyable than the destination. Keep on fixing them Andrew and I'll be watching from this side of the pond.  :D :D

Cheers  :beer:

Don

PS: Looks like DavidA beat me to the explanation. I guess that makes it unanamus..
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 24, 2014, 03:33:28 PM
Today I finally made a start on making a replacement take up spool. The original spool is in a sorry state. The two sides screw together to allow taking the used wire off easily. The threads have stripped, and some previous owner has wrapped the male side with PTFE tape to allow it to grip. Also the side cheek on one side has cracked and been rather crudely glued - time for a replacement.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 24, 2014, 03:40:49 PM
I decided to use polycarbonate, as it machines well and is pretty tough and resilient. The original spool cheeks are moulded, with a tapered lead in to guide the wire provided by a perspex disk insert. To replicate this I chose 6 mm polycarbonate sheet which I can taper on the lathe having cut the basic shape on the CNC mill.

The hub diameter is a nominal 60 mm and I found a suitable rod of 70 mm on eBay for an acceptable price
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 24, 2014, 03:43:01 PM
So the first thing to do was cut a male spigot on the polycarbonate rod -
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 24, 2014, 03:54:36 PM
So having made that, parted it off, and made a second one (I had decided to make two new spools) I had to cut the female thread in the end. This was not only needed as half of the hubs, but also to hold the male threads for their 'second operation' of facing off and boring to size.

I realised that screwing the male into the female, then boring and  turning the female would tighten the thread, so I made sure that the two mating faces were as clean and smooth as possible. Even so they locked up good and proper  :bang: To get them apart I ended up knurling the unthreaded bit so that a strap wrench would have half a chance of gripping. I also used a thin parting tool to cut a slot between them in an attempt to relieve the tension. Eventually they came apart. The knurled bit is where the hub will be bonded into the cheeks so won't detract from the finished spool.

To avoid the same issue on the second one I hit on the idea of wrapping a soft copper wire round the junction between the two components, so that when turned on the lathe the wire could be pulled out with pliers to relieve the tension, and it worked quite well.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 24, 2014, 04:00:41 PM
So tomorrows job is to start on the cheeks. I'll cut the profile and windows on the CNC mill, then taper the cheeks on the lathe
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 25, 2014, 10:37:44 AM
Bit of a late start today as I had to fell a tree that was threatening to push a wall over  :bugeye:

Got the spool cheeks drawn up in CAD and into FeatureCAM to produce G code. Made a test cut / protototype from an off cut of Perspex that had been originally the splash guards on this machine. Perspex doesn't machine quite as nicely as polycarbonate but is was just to prove the process.

I wanted to engrave the word 'FANUC' on the reel cheek as per the dxf Phil kindly generated, but it produced more code than the TNC355 can gobble up - I'll run it as a drip feed second operaton - but at least this made a good prototype.

The perspex one may even get pressed into service to repair the original!
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 25, 2014, 04:23:56 PM
A bit more experimenting this evening, and I've reduced the G code of the logo from about 1500 lines down to 235  :ddb:

This has let me download it to the TNC355 Heidenhain controller and cut a test engraving, which has come out acceptably. Thanks Phil  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: philf on November 25, 2014, 06:23:42 PM
A bit more experimenting this evening, and I've reduced the G code of the logo from about 1500 lines down to 235

This has let me download it to the TNC355 Heidenhain controller and cut a test engraving, which has come out acceptably. Thanks Phil

Looking good Andrew.

I'm surprised that it translated into 1500 lines of code. Did it turn all the rads into a series of flats?

About 20 years ago I created some code so that our toolroom could engrave serial numbers using their CNC mills. They would CNC incredibly precise microwave components and then have to engrave them on a benchtop Taylor Hobson pantograph engraver.

This made the engraver redundant and it ended up in my workshop.

Cheers.

Phil.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 26, 2014, 03:17:20 AM
Phil, the first attempt was removing all the material bounded by the letter outline, whereas the second was a simple line outline.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 26, 2014, 10:12:50 AM
So today I churned out four cheeks on the cnc milling machine
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 26, 2014, 10:14:33 AM
Each had to have one side (it's inside) tapered to help guide the wire. This was done on the manual lathe
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 26, 2014, 10:15:47 AM
So then it was a case of a trial assembly, then gluing them together
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 26, 2014, 10:21:52 AM
So this little mini projectette is almost done.

There is a tapered sleeve that the wire actually winds on that I need to make. It has a parallel bore but a steeply tapered outer diameter so that it can be pushed out of the wound wire easily to recover it for re-use. It is what sets the width of the spool, the screwy bits clamping it against the cheeks. The original has been broken into four pieces and bound together with tape! Two of them to make.

And also the spool is driven by a sliding peg that sits in a slot in the hub - there are four slots on each side of the spools, but only one is actually used. So that's another little task for when the glue has hardened - the makers claim 24 hours.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 27, 2014, 05:51:12 AM
So this morning I made the two tapered rings. These go on the hubs of the spools, the idea being, when you want to remove the scrap brass wire, the ring comes off with the wire and as it is tapered will then push out of the wire easily. Remains to be seen if this theory works - the original was always a pain to remove, but it had been covered in masking tape to hold it together. I increased the taper to 8 degrees from the original 5 degrees to help removal, and also made the rings a couple of mm thicker so hopefully they wont suffer the same cracking fate as the original.

I only just had enough of the 180 mm x 70 mm polycarbonate rod left to make them - the chucking bit was really rather short  :bugeye: But it worked  :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 27, 2014, 09:29:27 AM
This afternoon I've milled the drive slots and assembled the spools and installed one on the machine - seems to work which is just as well after all this faffing about  :ddb:

So I think, barring accidents that just about wraps up the mechanical side of things.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on November 27, 2014, 09:41:29 AM
Next job is to upgrade the memory. As previously stated this (and other Fanuc 6 controlled machines) uses 'Bubble Memory'. When I got the machine is came equpped with a 16K byte memory which (rather charmingly) they refer to in the manual as 40 metres of paper tape equivalent.

I got my sticky fingers on a 128K memory board shortly after I got the machine and installed it. The process is a bit complicated for two reasons. Firstly the bubble memory contains all the machine parameters including those needed to drive the RS232 interface, and it's that interface through which you need to re-load all the parameters. A bit of a chicken and egg situation! This is circumvented by manually inputting just the bare comms port settings and then re-loading. But before you do this you have to manually load all the 'Defect Loops'. When these memories were made not all the internals were perfect, and any defects are noted on a table on the card.

But now another bubble memory drifted into sight recently (ebay in the USA) - this time a whopping 512K byte or 1280 meters of paper tape  :lol: This is the maximum memory size for this machine. It arrived yesterday so I must revise the procedure, take numerous back up copies of parameters, cutting data, and ball screw error corrections, and go through the process again. At least this time all the data is retained in the memory that I remove, as bubble memory is 'non volatile' rather like core store used to be. So in a worst case senario I can re-install the original and start again.
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on December 19, 2014, 12:21:39 PM
Well to cut a long story short - no, the replacement Bubble Memory didn't work. I'm sure that the seller sold it in good faith but it fails to clear when told to. Currently in transit back to Knoxville, Tennessee curtisy of the ebay returns system, foc to me, and paypal are arranging a refund.

However I sourced a second one here in the UK, and that worked first time and is in and running  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: DMIOM on December 19, 2014, 12:28:17 PM
Maybe because there's a ghost trapped in the bubble? - (or is it a version of 'the genie in the lamp'?)
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on December 19, 2014, 12:38:14 PM
One of the other minor irritations that's been outstanding is a non working bulb holder. The "+V" axis motion button is a simple momentary 'press to make', that incorporates a bulb holder, the 24v flange bulb illuminating when the V axis has travelled to the 'Reference Position'. The contacts of the holder had disintegrated and none of my rescued spare buttons were suitable.

Compatible button available from RS for £26 but you pay extra for the bezel / label assembly, OR for £8 I can buy ten of them from Hong Kong, however these have a 24v LED built in.

Well as you may guess, I got them from Hong Kong and they arrived by today's post. Pretty tortuous fitting as it had to be done in situ as the control panel doesn't easily remove. However only four soldered connections.

Got it in, made a reasonable job of it, tried it, and the button is illuminated ALL the time  :bang:

Fortunately this bit of the machine I have circuit diagrams for, so off I went searching. Turns out that there is a bit of very clever design here. North end of bulb (or LED) goes to +24, south end goes to driver circuit which brings it down to 0v, but there is a 110 ohm resistor also going to 0v. Now I'm assuming here, but I think that it's true. That resistor is intended to keep the bulb filament warm but not glowing. I've seen it before in high reliability equipment  if you don't let the filament go totally cold both the bulb and the driver will live for far longer.

Well of course the 110 ohm resister was easily low enough value to light the LED which is happy at a few milliamps. Cure was simple, unsolder one end of the resistor and sleeve it. Now full functionality restored albeit with a slightly brasher colour to the light when lit !

.... however I'm chuffed to have found that   :ddb:
Title: Re: Titivating a Wire EDM Machine
Post by: vtsteam on December 19, 2014, 01:34:39 PM
I somehow missed this thread, Andrew -- another classic!

I remember reading about the fantastic bubble memory in Byte magazine-- early non-volatile memory, and wishing I could afford it. Oh think of the possibilities!!!

Great sleuthing the cause of the lamp issue, and those wire reels are first class.

 :clap: :clap: :clap:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on December 19, 2014, 01:45:52 PM
Thanks Steve for the kind words  :thumbup:

I'm not surprised you missed the thread seeing that you seem to hibernate for months on end and disappear off the face of the earth  :lol:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on January 07, 2015, 09:58:36 AM
Well at long last I've finished another time consuming 'sub project' that sprang from this re-build. Documentation

As I had obtained a brand new copy of the Operations Manual re-printed for me by Fanuc in Japan, it made my VERY tatty copy of the Maintenance Manual shout out for attention. The problem is that using the machine one's hands tend to be wet, which makes handling manuals in a way that will allow them to survive isn't easy.

I decided to scan both manuals into searchable PDF files with a view to having them available electronically as well as printing out and laminating key pages. Now I have a very nice HP scanjet scanner - (in fact I have two of them !) but it didn't survive the upgrade from Windows 2000 professional to Windows 7 Professional - drivers not available  :bang: So needing to buy another scanner lead me to discovering the PlusTek Opticbook 3800:

http://plustek.com/usa/products/opticbook-series/opticbook-3800/

Not the cheapest, nor the most stylish scanner in the world, but designed specifically to scan books and manuals, so is laid out with the glass very close to the front edge, allowing scanning right into (within 2mm) the fold of a book. Also comes bundled with some very useful scanning software. Even better, a brand new one popped up on ebay at less than half price  :ddb:

So I set to scanning - a laborious job - not too bad on the new manual but appallingly tedious on the tatty one that is literally falling apart. A bit of an issue cleaning up the scans (covered in another thread) :

http://madmodder.net/index.php/topic,10340.0.html

But having over come that I ended up with two humungous files. One of 219 pages and the other 313 represented as about 35 mByte each as pdfs.

Then I set myself the task of making the index pages dynamic, by inserting 'links' in the pdfs in the appropriate places to jump to the right page in the document. Three pages of index lines in the Maintenance Manual and another seven pages of links in the Operations Manual. Well this morning saw the end of that task thank goodness and I've actually been able to load them up to my iPad to view under iBooks AND the dynamic indexing works - quelle relief!

All I need now is a cheap waterproof iPad or clone for the workshop  :thumbup:
Title: Re: Titivating a Wire EDM Machine
Post by: vtsteam on January 07, 2015, 11:53:10 AM
The world of Fanuc wire EDM titivators owes you a great debt of gratitude for that, Andrew!  :thumbup: :clap: :clap: :clap:
Title: Re: Titivating a Wire EDM Machine
Post by: awemawson on January 07, 2015, 12:55:15 PM
He he ..... that would be me and ................... probably nobody else  :lol:



.... but if any one in the future needs a copy get in touch
Title: Re: Titivating a Wire EDM Machine
Post by: dsquire on January 07, 2015, 01:19:19 PM
He he ..... that would be me and ................... probably nobody else  :lol:

Andrew

Don't sell yourself short. I appreciate all the time that you have spent researching and repairing your EDM. I admire a man that can take something apart to see what makes it tick, then put it back together so it does tick. I look forward to more and when the widgets are finally rolling off the assembly line.  :lol: :lol:

Keep on having fun with it Andrew. That's what retirement is all about.   :D :D

Cheers   :beer:

Don