Titivating A CNC Plasma Table

[awemawson]

I'm glad to report that the panel is FINISHED - bar testing 

All the above list has been done, and I added an extra way to the DIN input for the the mains, and re-located the fan contactor to make the wiring neater. Just needs fitting in the cabinet, and thirty eight cables making off, but that won't happen today as I have to socialise (apparently)

[mattinker]

Hi Andrew, I imagine that it's too early for me to bring a lump of steel to cut out on tuesday!

Keep on titivating, all the best, Matthew

[awemawson]

Hopefully not long now Matthew 

I managed to sneak out for a couple of hours this evening to get a bit more done.

Firstly I found that the 'one in three out' IEC input module wasn't as I'd assumed all connected in parallel, but the 'three out' were in parallel and separate from the input socket - soon cured with some soldered links.

Then I installed the panel in the cabinet and wired in the mains and sorted the main chassis earth.

Then I started on the input / output wiring and managed to get the four stepper motors coupled up. No time to test but good progress. More socialising tomorrow (our wedding anniversary so out to lunch with the wife, and a drinks and nibbles party later so limited time, but hopefully I can get some of the limit switches wired in.

[awemawson]

A productive morning 

First I installed the PC in it's mounting sleeve on the electrical enclosure and connected it to the panel electronics by it's Ethernet port - this allowed me to test the stepper motor wiring that I did yesterday, and amazingly everything worked as it should and turned in the right direction 

Then I wired up the limit switches - just repetitive making off of cables, teasing out the screen and using a bit of heat shrink to hold it all together (hot air guns are HOT - ask my right arm how I know    )

Testing the limit switches MACH3 immediately went into ESTOP - it turns out that 'Z-UP' input has been programmed for ESTOP - as a temporary measure I've disconnected it, and will probably long term wire 'Z-UP' and 'Z-DOWN'  limits in series. At least it shows me how I can implement ESTOP easily - I have the button, just not mounted it yet. (Previously he had only implemented Z-DOWN, X-NEAR, and Y-RIGHT)

This just leaves me a few things to sort - mainly the interface to the plasma cutter. The existing cables are in a dreadful state. The control cable (like many on the original machine) had no cable clamps fitted, and wires were pulled out and VERY dodgy. I've managed to source clamps from similar (but not identical) connectors so will re-make the entire cable. The connectors are crimped, and the pins in the shell at the Hypertherm end are not ones I've been able to source, however the ones at the table end seem to be identical to the ones used in 'D-Type' plugs and sockets for which I have the pins and crimps. I just hope extracting the existing pins doesn't destroy the shell.

The second cable from the Hypertherm carries the full 'Arc Voltage' - which can be as high as 250v, so I don't think the original use of car type 'bullet connectors' is a good idea  Searching high and low for a plug / socket arrangement that was suitably compact there is not much to choose from. I ended up with "Neutrik NAC3FCA" or possibly NAC3FCB. It seems one conventionally is used as a source and the other as a receiver, but they look very similar to me (I bought a pair of each to let me choose) I've never seen these connectors before, so if anyone else has experience please advise.

Another thing to sort is the PC Monitor support - again it's taken on a list to starboard - a bit of judicious bending is probably called for 

[mattinker]

I wish there was a like button!!

See ya, Matthew

[awemawson]

Today was a cable sorting day - my main concern being the control lead from the Torch Height Controller to the Hypertherm cutter. It had seen better days, no cable restraints in place at all, wires stretched - why do people let things get this bad 

It needed shortening considerably, and I had to be able to rescue the Hypertherm end as I had no way of re-crimping new contacts in it. By cutting the cable shorter, cutting back the torn outer insulation at the connector end, and warming the wire under an electric hand drier I was able to encourage the sheath to move back down to the plug so that the new cable clamp would grip it 

Then, moving to the Torch Height Control end I (having taken a reference picture first!) pushed out the female pins, and crimped new ones onto the shortened cable. Now pushing pins out is not always successful, as the plastic of the shell has to deform to allow the pin out, and this means that the new pins are not always retained properly. As I was dismantling it, one wire came out with no pushing, and a pin wouldn't retain in the hole - so someone has been here before  Luckily I'd had a delivery of gap filling superglue this very morning, and a tiny drop on the pin did the job 

It was a case then of making up the chassis sockets for the Torch Height Controller and screwing them in place.

[awemawson]

Now the Plasma Arc Voltage lead emerges from the Hypertherm 45 plasma cutter though a 1/2" hole with no cable restraint (common theme here  )

So I decided to pull the Hypertherm apart to see what could be done - turns out I'm going to have to buy a special cable gland as nothing that I have will fit. While in there having blown the dust out, I made a crude temporary restraint from a Tywrap and I must order up the right bit.

While I was at it I added a 90 degree elbow to the air feed to get the pipe pointing in the right direction when the Hypertherm 45 is sitting on the 'plasma perch'

This let me put everything back together, and theoretically everything is ready to work. There are a few little things I'd like to sort though before it returns to the welding shop:

a/ New castors - it's sitting on some I had on the shelf, but they are not locking, and the table moves with the inertia of the carriage - new locking ones arrived earlier in the week.

b/ I want to re-do the mains input to allow me to power up the PC without powering up the controller, so incorporating a three position switch (OFF, JUST PC, PC and CONTROL)

c/ Remake the belt covers - the ones on it are crude and rattle all over the place

d/ Fit an ESTOP switch

[vintageandclassicrepairs]

Hi Andrew,
This project has gone way way past titivating 

May I add my 2 cents worth on the electrical panel build ?
My job used to be a spark/ inst tech (34yrs) and I have built innumerable panels for new projects and retrofits

Where mains voltage is involved, 
The panel door should be interlocked usually through an isolator with door mounted handle, so the panel door cannot be opened when the isolator is in the "on" position
A second option is a micro switch on the door operating a mains contactor rigged up to perform the same task

Regards
John

[awemawson]

John, i agree in principal, and I have both an interlock and a cut out that I could fit, but probably won't. The control box will only open with the right key, and it is for my own use in a non-commercial environment.

As it happens I'm slightly revising the mains wiring today

[John Swift]

Hi Andrew

the Neutrik power connectors can be seen on this mains distribution unit with the blue colour coded inlet
http://www.canford.co.uk/CANFORD-MDU7-AC-MAINS-POWER-DISTRIBUTION-UNIT-12x-Powercon-outlet-Powercon-inlet-with-Powercon-loop-out

they look a lot better than the "mains XLR connectors" 

     john

[awemawson]

John, I've assembled and fitted the blue series and must say that I'm quite impressed with them as a robust solution - went in nicely with no drama's and are very compact for their 20 amp rating - not that I'm using them to carry that - probably a few milliamps at most !

... so much better than the previous 12v bullet connectors 

[John Swift]

Hi Andrew

I have always thought Neutrik connectors are worth the extra money

I don't know if you found the mains connector you have used have passing resemblance to the
speakon connector -

http://www.canford.co.uk/Products/43-081_NEUTRIK-SPEAKON-NL8FC-Cable-connector

they could be a useful   2 to 8 pole connector 

    John

PS

I can't wait to see your project for  2017   

[awemawson]

Sorted a couple of little irritations this lunchtime.

I was fed up with the PC/Keyboard arm being on the slant - I'd intended to pull it off and give it a permanent 'set' in the press, but if I changed the monitor or keyboard (quite likely) the weight would differ and it again would tilt. I can up with the idea of making it adjustable, pressing a stainless steel hinge (that I happen to have left over from another project) into service to mount a tilting flap onto which the arm could fix. Then a simple screw adjuster would let me tilt it at whatever angle that I wanted to achieve a level keyboard and monitor. Works like a charm 

I was away yesterday and last night, and came back to a pile of electrical goodies to re-arrange the mains input side of this machine, which is something for another day. But also in the pile was a packet of PG9 cable glands, so at last I've properly secured the 'arc voltage' cable where it comes out of the Hypertherm Powermax 45 plasma machine.

[awemawson]

The panel door should be interlocked usually through an isolator with door mounted handle, so the panel door cannot be opened when the isolator is in the "on" position

Regards
John

John, your post got me thinking, and I've decided that to put in a cabinet isolator is not only sensible, but resolves other issues on my mains wiring revision, so although I had one in stock I've ordered one that's slightly smaller and hence more convenient for this cabinet and fitting it is the next job, so thanks for the prompt 

[awemawson]

After super this evening, I fitted the electrical interlock that prevents the cabinet being opened when powered up. Not wired in, but that's the easy bit - getting the door actuator part and the inside switch part correctly aligned takes a bit of careful measurement. To be effective the interlock needs to be on the far side away from the hinges, or there would be too much leverage and it would easily be broken. Ideally it should be on the right hand side at the same height as the mechanical lock, but that wasn't possible, so it's in a compromise position which will be fine.

[awemawson]

I pressed ahead and mounted the controls on the cabinet door this morning. I debated long and hard (with myself!) whether to put them on the side where wiring would be much easier, or whether to put them on the door, where the ergonomics are much better, but the wiring will be a pain (hinged door, so cables need to flex, and be supported across a door that I don't want to drill holes in)

It's always a bit of a worry drilling that first hole in things like this - spacing has to be EXACT so that the engraved label would fit, and all sit nice and square on the door. I cheated, and using the same file that I created the engraving and cutout holes from, I made a drilling template with 3 mm holes where the 22 mm cutouts would be. Drilled the first 3 mm hole and bolted it with a nut and bolt, squared the panel up with a set square, clamped it, drilled a second hole, another nut and bolt, then drilled the remaining four 3 mm holes. This done, I opened them up with a 'step drill' to 22 mm for the controls. Step drills are superb for this sort of operation, and the final hole is remarkably concentric with the pilot.

[vintageandclassicrepairs]

Hi Andrew,

so thanks for the prompt

You are more than welcome
Maybe some adhesive backed slotted trunking and or spiral wrap and some sticky back cable tie thingys
across to the hinge side of the door ?
Neat job on the switch mountings
I have a few Greenlee hole punches that leave a nice clean edge, since my "real job" days
(like this)
http://www.ebay.co.uk/itm/Greenlee-Knockout-Punch-and-Die-Set-1-2-CONDUIT-7-8-I-D-PAT-1817223-/302163983305?hash=item465a607bc9:g:quoAAOSwiDFYNlJa

Happy New Year
John

[awemawson]

Thanks John.

In the end I used Tywrap sticky pads across the cabinet door. Scrupulous cleaning with IPA first as I've had bad experiences with these things falling off in the past. I used to have problems with printed labels curling off until it dawned on me that many painted surfaces have been buffed with silicone containing polishes, and the thorough wipe down with IPA has cured that problem. Hopefully it'll do the same for the sticky pads 

The wiring is now mostly completed, just awaiting the arrival of a relay for the E-STOP circuit to drop the power to the stepper drivers, but E-Stop into MACH3 is up and running, as is separate switching for the controller and PC along with the relevant indicator lamps.

Still need to sort out the extractor fan duct, and cut a 12" diameter hole in the right place in the welding shop wall for the exhaust and make a cowl for it. Also need to sort out the driving of the fan relay from MACH3 - the plan is to bring it on when cutting first starts, and turn off 10 seconds after cutting ceases.

[awemawson]

Still waiting for the E-Stop relay, but I went ahead and finished off the door cable form.

[RobWilson]

Very tidy wiring job Andrew. 

Rob.

[awemawson]

Thanks Rob.

Today I attacked the problem of driving the extractor fan from the MACH-3 program with some help from folks on the MYCNCUK.COM forum - thread is here:

http://www.mycncuk.com/threads/10490-MACH3-Plasma-help-please

After a few blind alleys I found my way through the maze, and now can control the fan either by G codes or by an on screen button 

To clebrate, I thought I'd have a go at tidying the 12" ducting on the fan. The basic issue is that the 'suck' end of the fan has a flare making it too large to comfortably slide the flexible ducting over. I'd intended to buy larger ducting, but it's mighty expensive, so I decided to roll up a sleeve to fit inside the flare thus presenting a parallel 12" pipe.

As the fan had a grille fixed with four clips I decided to re-use it and have the sleeve fixed by the same bolts. Worked out very well and makes a far neater job of the ducting 

[AdeV]

Tidy job as usual Andrew, but, no JCB yellow paint?

Quick unrelated question - what's that "green graph paper" desk cover thing you've got, and where does one obtain such a thing?

[awemawson]

Thanks Ade - no yellow, but it does have Ford Tractor Blue appearing everywhere I've been 


Cutting mats abound in my usual department store (eBay  )

An example:

http://www.ebay.co.uk/itm/Babz-A3-30-X-450MM-NON-SLIP-CUT-CUTTING-MAT-BOARD-ART-CRAFT-Babz-Media-Ltd-/152381802475?hash=item237aa9c7eb:g:hfIAAOSw241YbBGn

[awemawson]

I've been twiddling my thumbs waiting for a relay to arrive to use for E-STOP. This gave me a bit of cogitation time, and I came to the conclusion that I just HAD to sort out the wonky belt covers that were installed. 

It's one of those things that don't need to be done, but as they are they look tacky 

[awemawson]

Now looking to see how to mount more satisfactory covers opened a whole bag of worms 

It tuns out that the HIWIN rail sliders, which each mount with four screws, all have two screws missing, and more to the point, the holes drilled for them are in the wrong place  It's almost as though the gantry assembly was originally on a different sized rail with different sliders Now all it needs is holes drilling in the mounting plate in the correct locations, but realistically this involves dismantling the gantry - something I don't really want to do 

The HIWIN sliders have ports to mount grease nipples but none are fitted - not sure if they should be in this application - comments welcomed 

And even worse when looking at the Z ballscrew lower bearing it is at a significant angle - certainly not mounted perpendicular to the shaft, but it turns smoothly - I can only assume it is a spherical self aligning jobby - I'll have to dismantle it and find out - looking upwards from the bed using a mirror, of the four mounting screws, three are missing