New plasma cutter build with LinuxCNC controller

[xnaron]

I just finished my controller build for a LinuxCNC based plasma cutter. I am building a new machine to replace my smaller modified crossfire. The new machine will have a cut capacity of 48 x 36".

The components I am using for the controller:

Mean Well SE-600-48 - 48V @ 600W power supply for stepper drivers
Mean Well RS-25-5 - 5V @ 25W power supply
Mean Well HDR-15 - 24V power supply for THCAD Ohmic
Mean Well LRS-150-24 24V @ 156W

DM556T Digital Stepper Driver 1.8~5.6A 20-50VDC

Mesa 7i96
Mesa THCAD-5 Ohmic
Mesa THCAD-5 THC

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Here is the old machine with cutting capacity of 24"x22".

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[acourtjester]

Good start keep showing your progress.

[plasmanewbie]

Wow man, nice tidy setup on the control box. Did you do all that yourself?

[xnaron]

Wow man, nice tidy setup on the control box. Did you do all that yourself?

Thanks. Yes this is the second one of this style I have built. Here is the first one based on UCCNC AXBB-E

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[plasmanewbie]

Super nice work

[xnaron]

Super nice work

Thank you

[xnaron]

A goal of this build is to use as many of the parts I have on hands from old builds. I have a lot of 25-50100 8020 extrusion that I will be using. The frame will be laid out like this. I will be cutting the brackets out of steel, probably 11 gauge ish. I am planning to get a water table made with a 4'x3' cut area. I will be using linear rails and rack and pinion drive. I have enough rack left over from my last build that will be enough for this build. My goal is to keep the gantry as light as possible. I'll use a similar z mechanism to the one on my last machine. In fact I just may remove it from that machine and transplant it on this one.


Looking at the front left of table. I will have a frame near the bottom of the legs that will hold a shelf. I think I have some left over unistrut that will work but might need to get some angle iron.

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Found these on amazon.ca and the price was right. Reviews were good. Too bad this was the last set.

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These pictures are of one of my first CNC router builds from 2008(was decommissioned and disassembled in Oct 2019). I used 1.5" angle iron to hold the ~2"x1.5" unistrut to hold the table bed. I will reuse these on my new machine. The dimensions will be smaller though.

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[xnaron]

I cut out one of the caster mounts for the 5010 profile and designed the 5010 corner brackets. The ones with the holes will allow t-nuts to be passed through and will be positioned at the back of the machine.

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[xnaron]

The linear rails I am using require 4mm screws. The only tnuts I had on hand were 1/4". I designed a strip of 13 tnuts. I spotted the holes with a 20amp drill operation and then hand drilled the tap size for 4mm. Then a little cleanup on the belt sander and used the bandsaw to cut them apart. Then a quick coat of the black bedliner paint and done. It took about 2 hours from design to production to make about 120 4mm tnuts.

I was a bit worried that they might not be strong enough. I tested to failure with a 4mm screw and the threads on the screw stripped and the threads in the tnut were fine. I should have tested it after I made a few not 120.

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[Rodw]

A very cool idea. I think you will be fine with your M4 screws. A friend of mine reckons you only need 3 threads to hold something and now I've tried it a few times I believe him! So with 1/4" you will have about 9 threads holding.

Sometimes I will use a metric fine thread to get closer to that 3 threads. On my table, I used M10 x 1.25 pitch metric fine threads to hold a massive 12mm piece of steel so I had 3.2 threads through my 100 x 100 x 4 mm wall square section frame.

[robertspark]

for a quick drill and tap operation (in aluminium or thin plate). I've had good success at using drill taps such as these..... especially where I have had to do a lot of threading (like joining extrusions / extrusion brackets), always use cutting oil though (YMMV)

https://www.ebay.co.uk/itm/183809450108

I like your t-nut idea

[xnaron]

A very cool idea. I think you will be fine with your M4 screws. A friend of mine reckons you only need 3 threads to hold something and now I've tried it a few times I believe him! So with 1/4" you will have about 9 threads holding.

Sometimes I will use a metric fine thread to get closer to that 3 threads. On my table, I used M10 x 1.25 pitch metric fine threads to hold a massive 12mm piece of steel so I had 3.2 threads through my 100 x 100 x 4 mm wall square section frame.

Thanks. I was more worried about the threads in the mild steel not being as strong as the (assumed) more hardened steel used in the manufactured ones. The mild steel will be fine from my test.

[xnaron]

for a quick drill and tap operation (in aluminium or thin plate). I've had good success at using drill taps such as these..... especially where I have had to do a lot of threading (like joining extrusions / extrusion brackets), always use cutting oil though (YMMV)

https://www.ebay.co.uk/itm/183809450108

I like your t-nut idea

I have seen those used before. I have found that drilling holes out cut on the plasma can be really tough when the edge gets hardened. The drill op at the 20amp setting dimples the hole and led to better success however the accuracy of the hole isn't great. I've read this is due to the inaccuracy from the initial pierce arc.

[Rodw]

Also, the Linuxcnc spotting is a good feature which may increase accuracy. I have mine set for a 220 ms on period. Any less then that and the plasma won't turn on. I think the Hypertherm is a bit slower.

I have not had any problems drilling M3 clearance holes on spots with perfect alignment to machined tapped holes.

[xnaron]

Also, the Linuxcnc spotting is a good feature which may increase accuracy. I have mine set for a 220 ms on period. Any less then that and the plasma won't turn on. I think the Hypertherm is a bit slower.

I have not had any problems drilling M3 clearance holes on spots with perfect alignment to machined tapped holes.

Interesting. Are you spotting at pierce or cut height?

[Rodw]

I never gave that any thought. I guess it would be at pierce height. I use the plasmac post processor for sheetcam and the custom tool CENTER SPOT from memory. I just create a separate layer for all the holes. I supppose you could alter the pierce height for that tool.