The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)

[russ57]

My tig has also developed a fault. Pilot arc but no welding current.
Since it is a combo machine I also have no mma or plasma cutter...
A Rossi super p200iS, probably sold under many labels. Just a baby compared to the ones just mentioned.
If anyone has a circuit or service manual....

Russ

[awemawson]

Interesting stuff in the pipeline! What make is the TIG welder? My Miller / Interlas 320ABP weighs about 400kg and you could almost climb inside - sounds similarly unwieldy. Takes something like 70A from 240V single phase on full chat.

It seems that it is a "BOC TransTig 350" but is not in the best place for photographs, as it is facing the wall !

[AdeV]

So... are you keeping this lathe? Or selling it on ready for the next pig-in-a-poke you see on eBay? 

In fairness, this is a brilliant restoration, it makes me want to get on with the Mazak but I've just got too much other (non workshop) stuff going on, and I'm not entirely sure I've got the patience or methodological mindset to get mine working properly.... although I'd really like to try.

[awemawson]

Ade
No plans to dispose of it, and loads still to learn using it. But then I had no plans to dispose of the Traub

But I must dig out the Denford Mirac and sell it as I don’t need two CNC lathes I think

[awemawson]

Today I was supposed to be fitting a "Tramp Oil" skimmer to the TC20 coolant tank. Tramp oil is the stuff that floats on top of soluble oil, and is derived from the 'total loss lubrication oil' in the main, and a bit of the soluble oil that might have separated. In industry it also comes from oils put on stock to prevent rust in storage.

Why is it a problem? Well when it covers the full surface of the coolant it prevents oxygen entering, and this promotes the growth of anaerobic  bacteria which is a 'bad thing' generating bad smells and  potentially bad corrosion products.

You can reduce the problem by adding tablets that chemically kill the bacteria, or a 'fish tank bubbler' that oxygenates the coolant, but far the best thing to do is remove the oil before it becomes a problem.

So how does the skimmer work: Dead simple really. A belt, driven by a slowly rotating motor, dips into the tank, with a heavy roller on it's lower end to keep the belt reasonably taut. As the belt rotates, the surface oil tends to stick to the belt, and towards the top of the belt is a scraper that removes it into a duct leading to a 1 gallon can.

Well get on and fit it then! - I can't - it WASN'T delivered today as promised 

But RS did at least deliver the Harting heavy duty 'HAN' plug and socket that I decided to use for it, as this style was already in use on the machine, so I did get that fitted in readyness.

I'll have to trepan a large hole in the top of the coolant tank, but that had better wait until the skimmer arrives so that I can check sizes, as I'll have to fabricate a bracket for it anyway.

(Picture here is of a similar belt skimmer that I fitted to the Beaver Partsmaster CNC Milling Machine)

[AdeV]

I'm sure I've mentioned this before.... but I use this stuff: http://www.lubetechshop.co.uk/product_info.php?cPath=25_51&products_id=291

Last time I put any in the Bridgeport CNC sump was, um, 3 years ago? Maybe 4 years now. No bad smells yet! (and it still looks like it should do, hasn't gone lumpy, etc.). I've not got a skimmer either, so there's definitely a layer of tramp oil on it...

[awemawson]

I'm sure it's fine Ade, but a brief bit of Googling doesn't reveal any actual product data re sulphur, chloride  or silicone content etc nor does anything make reference to grinding operations 

At least the Castrol products abound with specifications and data. My local oil supplier (Rye Oils) will sell me extremely cheap 205 litre drums of 'General Use' soluble oil, but I avoid it for the same reason.

My advice is to somehow get rid of your tramp oil, you may not yet have suffered any ill effects, but they are very well documented.

What Brix do you dilute it to ?

[AdeV]

I'm sure it's fine Ade, but a brief bit of Googling doesn't reveal any actual product data re sulphur, chloride  or silicone content etc nor does anything make reference to grinding operations 

The same place sells another soluble oil suitable for grinding - it's a bit over £100 for 25l, but I've no experience of that one.

I'm sure if you e-mailed the shop they'd send you technical data, MSDS, etc. Personally, I've never bothered, and it seem to work fine.

What Brix do you dilute it to ?

Brix?

I put about 20l of water on 5l of oil, so around 10% or so.

[awemawson]

My quest was to find a soluble oil that I could use across all my machines and metals, so manual lathe and mill, CNC lathe and mill, and also a cylindrical grinder and a surface grinder with soft and hard steels, brass, aluminium etc. The Castrol Hysol SL 37 XBB  does this and, like the stuff you mentioned, is a bit over £100  per drum.

Brix is the concentration scale for things dissolved in water - commonly sugars but in our line also soluble oils. You measure it with a refractometer by placing a drop of the mixture on a glass window, trapping it with a cover and measuring the refraction by looking through the calibrated eye piece.

(Very handy for checking the concentration as time goes by and evaporated water has to be replaced - I had to add 6 gallons of water the the Partsmaster yesterday  )

[awemawson]

Yesterday the Tramp Oil Skimmer arrived, so I was able to weld up the 'gallows bracket' to mount it, and give it a coat of the obligatory zinc rich primer and satin black top coats from a rattle can.

(Incidentally having replaced the wire rollers on the Migatronic welder has made a world of a difference to it's performance)

The base, which I cut on the CNC plasma table so I could radius the corners and cut a slot for the vertical, is held down on rare earth magnets on Delrin stand offs that allow me to adjust the depth of immersion.

Today I assembled it, put the correct plug on the cable, trepanned the hole in the tank, and installed it with a 5 litre catch can.

The belt is rather creased from being crammed into it's box, and the drive is a bit hesitant at times, but when it gets soaked in coolant I'm sure it will be fine.

. . . .coolant . . .that reminds me . . .it hasn't been delivered yet 

[tom osselton]

Nice job! What rpm does the skimmer run at?

[awemawson]

Thanks Tom, I'm guessing 50 - 60 rpm

By the way, the barrels of coolant arrived gone 5 pm this evening so guess what I'm doing tomorrow 

[Johnny Bravo]

Was good to catch up the other day Andrew. Will be interesting to see the lathe up and running with the Renishaw probe ...

[PekkaNF]

What material is that skimmer belt? Long time ago I saw stainless steel foil.

Pekka

[awemawson]

Johnny, yes good to meet up again, and yes . . .the Renishaw Probe . . . PK seems to have gone awfully quite over the past couple of months, I must give him another call next week.  I've had to 'bag up' the cables that should connect to the bits he currently has, to avoid the coolant getting into the connectors and trunking 

Pekka, the belt material looks like the backing used for rolls of silicon carbide abrasive, but without the abrasive of course. Reading the instructions, the green side should be  inside touching the roller surface, so I turned it round, but the one on my milling machine has been the other way round for the last five years and is working fine !

So I set off today to dilute the coolant and pour it in. Bucket chemistry (literally) - I was aiming for Castrol's recommended 9% concentration. Easy really with a 10 litre bucket with a calibration line, and a lab pyrex 1 litre calibrated flask.

Initially I just put 10 litres in, and left it for a while, as I needed to build confidence in the tank base. When I grit blasted it and re-painted it all those months ago, there were a few corrosion pits that might have had pin holes. I'd rather have 10 litres on the floor to mop up than the 95 of a full tank !

All seemed well so I went ahead aiming to put 70 litres in, then stop and check the dilution with my Refractometer. However my 10 litre bucket sprang a leak at 30 litres and I had to revert to a 9 litre one that I had, just making the maths fractionally harder !

Getting to the 70 litre target, I then set the machine pumping coolant around to make sure it was reasonably mixed, as of course each 10 (9) litre batch will be slightly different.

Amazingly the refractometer showed bang on 9% Brix - sorry about the photo, but you try holding the refractometer against the iPhone and pressing a button - I ended up using my tongue to press the button 

So then I took the tank up to 'almost full' and left it pumping. The Tranp Oil Skimmer is working overtime, as of course over the months that I've been working on the machine, the automatic slide lubricators have been faithfully pumping slide way oil to the needed place every few minutes. I've seen (so far) moths, flies and small spiders dragged out by it so they've obviously been having a party in the tank !


 

[awemawson]

I admit to a nice inner glow and a not inconsiderably swollen head after today's achievements 

Wanting to add a 'Wash Down' facility - ie a simple hose gun off the coolant pump to manually wash chips away and clean up a work piece, I decided that I needed a pair of valves acting in anti-phase. One in line from the coolant pump to the Tool Turret, and a second one from the coolant pump to the gun of the wash down facility.

Dead easy with relays and buttons, but I thought, why the heck should I be adding MORE buttons when the 820T is crawling with ones that have never been implemented, and there's a perfectly good PLC program running that I aught to be able to modify.

Having identified the input addresses of the front panel buttons that I wanted to use (I96.3 and I96.4) and found two spare 24 volt digital outputs (Q2.6 and Q2.7), with a bit of trepidation I started poking about in the PLC program live on the machine.

Now despite months of work learning about the PLC, it's 'STEP5' programming language, managing to down load and produce a paper copy of the PLC 'ladder logic', I have only before passively read what is in it and never attempted to edit, alter or add it it. So this is a first.

STEP5 is a very frustrating program to use to program, however today I've managed to add another 'Rung' to the ladder  (Segment 173 to be pedantic!) and amazingly it works 

Trivial in the extreme as far as the logic is concerned. One button sets an S/R flip flop, the other button resets it, and it's output controls one of the valves. Now I need to add subtleties to it, interlocking so it will only work when the door is open, will not work when the chuck is spinning or a program is running, and ensuring that when one valve opens the other closes, but that's finessing that can be done at my leisure, the point is I've proved that it's possible and I've managed to do it - hence the warm glow.

. . . back to reality - I need to go muck out and feed the pigs  !

[PekkaNF]

ommmmmmmMMMMMMM - gggggGLOW!

You can go down to nearest town with zipper open carrying a poster: I KNOW HOW TO PROGRAM S5 AND MAKE CHILDREN!

Pekka

[tom osselton]

Nice to see you can add to it, my mill just has a manual valve on the front of it I have to turn.




I haven’t had a swollen head since that frying pan incident! 

[awemawson]

Thanks Chaps!

I've been looking for suitable 17.5 mm pipe clamps to hold the extra pipes when the 'wash down' goes in. Couldn't find any so I printed some on the Cetus 3D printer in ABS at 99% fill

[awemawson]

Still not having the solenoid valves to hand to complete the 'wash down' facility I decided to finish off the alterations to the PLC ladder to prevent wash down when the spindle was turning, or the door open - fairly obviously you can ONLY wash down with the door open and don't want the pump diverted to the gun (which will hang on the door probably) with the door closed.

Again absolutely trivial code, but I discovered an interesting and useful STEP5 quirk while doing it. You can display the ladder diagram rung by rung, and set it to display the status of each node in real time. So in the following picture of segment 173, the door interlock node is displayed in GREEN as the door is shut and it's contact active - quite handy for fault finding I think.

So two rungs added:

Segment 173 is an R/S flip flop set and reset by the appropriate panel buttons, but inhibited by a closed door or a running spindle, and is reset by the general 'Reset' button on the machine. If the flip flop (= Flag 140.2) is set, Q 2.6 drives the 'wash down' solenoid.

Segment 174 merely takes the flag 140.2 and if it is NOT set activates Q 2.7 which drives the solenoid valve directing coolant to the turret and it's mounted tooling.

. . .seems to work so far . . .

[awemawson]

At long last the 24v DC solenoid valves have arrived so I've been able to get a better idea of the volume that they  take up. The various bits of brass plumbing have been to hand for days.

Dry assembling them and hanging them roughly in the place where I want them is the easy bit. The conundrum is to work out how to actually secure them such that not only are they firm enough to resist the inevitable vibration, but also such that they can be easily removed for maintenance.

All the joints will be sealed with Loctite 542 'pipe seal', which means that their rotational orientation can be set without making them actually tight until the 542 sets.

However there is nothing at all on the valves to fix them with. I've considered various methods - 3D printing a 'cradle'  - bending up brackets for the top and bottom 'nozzles' to go through - a bracket with hole that gets interposed between the nozzle thread and the valve - all have their pros and cons.

My current proposal is to braze a lump of brass to the central 'Tee' piece with ears to fix to the machine chassis, and hang everything off that.

[seadog]

They would normally be plumbed in to copper pipe which would support them. They're no different to standard zone valves in that respect.

[awemawson]

Absolutely so Seadog, but not when on flexible reinforced nylon ! So ...... I got on with making a 'flanged 1/2" BSP Tee Piece 

I found a suitable bit of 4 mm brass plate, marked it out, drilled it, cut it to size (always cut last - more to hold when drilling!) and then brazed it to the Tee piece.

I decided to use Cu-Phos brazing rods for two reasons - a/ I have a bag of it, and b/ it doesn't need any flux when brazing copper or brass - handy stuff but DON'T use it for boiler making. My supply is left over from years back when I was making up custom fittings for the 100 kW induction furnace.

So, wire them together, and have at it with my propane torch. I use MIG welding wire - should be soft iron wire but I don't have any. If you, like me, use MIG wire, anneal it first by flashing the torch over it getting it red hot. In the as supplied state it's too springy and is difficult to handle. Also getting it red hot forms a nice oxide layer which prevents the brazing sticking to it.

Not the neatest item but certainly functional 

. . .just need now to mark out the machine frame, drill and tap it, and fit the hoses and wire it up

[awemawson]

After lunch I drilled and tapped the machine chassis, and did a test fit of the 'Flanged Tee piece', before screwing all the plumbing together with Loctite 542  onto it, and aligned where they pointed.

While the Loctite was setting to the 'handling' state, I drilled a pair of 20 mm holes in a suitable place for cable glands to bring the digital output wiring to the solenoids.

Once the plumbing assembly had been screwed onto the machine I was able to pull cables through the existing ducting and wire up the coils of the solenoids.  Slight delay while I fed the pigs, then a grand tidy up and test. I'm pleased to be able to report that the front panel buttons, via the new PLC rungs, and out via the digital outputs, do precisely what I wanted. At power on, the upper solenoid is driven porting coolant to the turret. When the 'Wash On' button is pressed the upper solenoid is released, and the lower one is driven porting the coolant to the wash down hose. If the 'Wash Off' button is pressed, or the lathe sliding door is closed, the solenoids revert to putting coolant to the turret.

. . . sorted 

. . . except . . . I've not yet put the hoses on, I'll leave it until tomorrow for the Loctite 542 to fully harden before putting fluid though the assembly to give it it's best chance of not leaking !

[awemawson]

This morning I fitted the reinforced nylon hoses to the coolant system, pulling the one for the wash down gun under the machine from the rear to the front.

As the carriage moves both in Z and X it's important that there is enough slack in the hose to the turret for it not to pull itself off, so careful checks and a bit of trundling up and down got me to what seems the optimum length.

So time to test: firstly proving that the feed to the turret still works was successful, with only a minor leak requiring a Jubilee clip to be moved up the barb connector a bit and re-tightened.

Then time to prove the wash down gun. With the gun locked open I pressed the 'Wash On' which gave me a very impressive coolant jet well up to the task 

This is when the problem occurred 

Releasing the lock on the wash down gun, thus turning off the flow, produced a VERY impressive fountain of coolant from the back of the machine. Rapidly turning off the pump and going round the back it was obvious what the cause was. The high pressure from the pump was easily overcoming the Jubilee clip on the wash down gun hose at the valve end.

Now in hindsight this was predictable. The coolant pump isn't a normal vane pump that can run happily into a shut valve, it's a gear pump, and develops HUGE pressure when blocked - my fault entirely, I should have realised 

I think the solution is either a pressure release valve on the pump output direct to the tank, or possible just a simple mechanical valve allowing some flow even when the gun is closed.

However, having mopped up the flood, now I need to pack up the Racal RA17 communications receiver, as my roll of bubble wrap has been delivered. At least it will give me some thinking time.