Small CNC plasma table build DIY

[Plasma-art]

It has been a couple of months of planning, designing and sourcing parts but its finaly time to continue my build.
It's a metric build and not going to calculate everything to freedom units, sorry

Some specs:
Minimum work envelope 500x1000
(Nominal sheets are 1000x2000 or 1250x2400 so watertable ended up a little shy of 600x1300mm )
The regular db25 Chinese BOB and a custom BOB because of input pin shortages
DM542 drivers, 2x 32v 9 AMP psu's
Proma 150 THC
Intel atom 1.6ghz mini itx with extra parallel port card running Linuxcnc.
Cheap import plasma source that's going to be upgraded asap.

Pics or it didnt happen
This was a couple months ago, house needed some paintwork during the summer so prioritizing was needed

Electronics

20220704_132111_compress43.jpg

20220705_134730_compress55.jpg

Making the basic frame.

20220611_113803_compress27.jpg

20220611_134007_compress10.jpg

Got my carriage plates and watertable in, starting off with bearings on square tube because of issues getting SBR16 rails.
Frame got a little rusty but it is going to get sandblasted and powder coated when it's all done.
Now I am back to building because it's nice and sunny today.

20221012_135502_compress74.jpg

20221012_124946_compress74.jpg

[SRdesign]

“Freedom units”
Good progress so far. I like those tab and slot gantry plates, please post more pics once those are put together. Are those laser cut or plasma?

[Plasma-art]

I like those tab and slot gantry plates, please post more pics once those are put together. Are those laser cut or plasma?

Had them lasercut, only needed a slight bit of work with a file in the corners and they fit perfectly.
They are for 50mm square tube, took some inspiration from different builds and drew them up.

20221012_144544_compress81.jpg

The water table was also lasercut at the same company, total cost was around 120 euros.
I think these corners are not going to leak

20221012_145053_compress41.jpg

[SRdesign]

Good call on getting your water table bent up and only having to weld the sides. That is the one thing I regret about my table. I used angle iron and a flat sheet for the bottom of the water pan and welded the whole thing.… Horrible idea. If I could do it over I’d do it how yours is done. Keep up the good work.

[Plasma-art]

After I knew the price I went right ahead outsourcing it.
You just can't struggle with angle iron and hours of welding for the price a decent company can just cut and bend it.
Its not worth the time and effort.
One thing I do regret is not having adjustment slots for the bearings, guess I need to spend some time with the round file tomorrow.
Also need to get some more bolts so done for the day.
Should have a manual moving gantry tomorrow if all goes to plan and the weather stays dry.
Pretty much need to decide on the total height between the slats and gantry, cut 4 tubes and drill some plates for mounting the Y axes rails.
Cut and drill 2 pieces of flat bar with 2 holes and weld the Y axis tube rail to it so they can mount ontop of the Y axis carriages.
Only thing I do not have designed would be the Z axis so up to that point its alot of progress fast.

Should be cutting next week I hope.
Only problem is going to be the custom BOB, still need to get that thing made so no THC or no homing switches.

IMG-20221012-WA0005_compress14.jpg

20221012_154032_compress70.jpg

[acourtjester]

Did you Know if you use a UCCNC controller you can hook 2 of those BOB to it and have more inputs for the THC and switches. You can use that BOB and use one input for the Home/limits, one for the ohmic sensor and the other 3 for the THC total of 5 inputs. If you wanted a floating head switch you can sire it with the home limits too.

5_Axis_CNC_Breakout_Board_Interface_Users_Manual.pdf

[Plasma-art]

Already have a second parport in my computer, custom BOB is pretty much designed to work with linuxcnc with parport set to IN.
This gives me 14 inputs and 3 outputs extra and optically isolated.
Would like to go towards a mesa ethernet setup in the future when I have the cash for the upgrade.
The only reason I am not going that route is because they are out of stock for a while now.

[weldguy]

Great looking build so far, looks like you have done some good preplanning

[Plasma-art]

The weather hasn't be nice so the build has been at a standstill.
Put up a tent so I can do some more work on it.
Trying to get the moving parts atleast tacked in place today but as per usual hit another issue, let's say 230v AC tingled a little bit thanks to my drill that didnt want to make any more holes

This is the progress so far, got around 3 inches between the slats and the X carriage so that should be plenty.
Can of wd40 and 40x40mm tube for scale.
Probably going to have the next update next week.

20221015_121145_compress4.jpg

20221015_121212_compress5.jpg

Great looking build so far, looks like you have done some good preplanning

As far as I could plan things out I did however there are still some unknowns.
The Z axis for example, I dont have anything planned for that other then I do have a bunch of MGN12 rails laying around the place.
Also haven't planned any cable managment yet.

[acourtjester]

One thing that is a big help is using a boom for the Plasma cable, due to its large diameter. With a smaller table you can locate it in one corner as the torch only moves a short distance.

DSCN1668.JPG

[Plasma-art]

I am not sure if I am going to add a boom to it, probably going to hang it from the ceiling but I am going to keep that in mind.
Just have to see how it goes when it's up and running.

Also i lied about the update
I have borrowed a drill so I could get a couple of holes drilled In some flat bar and I could continue fabricating.
Did discover I sent out the v1 and not the v2 version to the laser cutter, not a big deal but I am missing out on some extra adjustment on the steppers.
Have just enough room for the nuts closest to the square tube.

20221015_154718_compress76.jpg

20221015_154933_compress33.jpg

One thing I also forgot was to countersink the holes for the bolts that attach the gantry to the carriages so I just shaved the head off of the m8 bolts instead.

20221015_154653_compress11.jpg

All in all it's starting to get there, everything is tacked including the X axis square tube so if I need any adjustments it's easy to take it apart.
Also need more washers and get idler pulleys sorted as I just used some bearings for mock up

20221015_154615_compress50.jpg

20221015_161045_compress89.jpg

Next would be getting the steppers mounted
Sort out the belts and the tightening system for them.
Fab the Z axis
Weld everything.
Wire it up.
Cut some steel

[djreiswig]

You could use socket head capscrews in the opposite direction to get some more clearance.

Screenshot_20221015-184814.png

[Plasma-art]

You could use socket head capscrews in the opposite direction to get some more clearance.

They do not have the clearance the other way around especially with a washer.
Second issue would be getting an Allen key in there.
It still works fine I am just lacking some extra adjustment.

Did some rough wiring today.
Gave it extra slack since I do not have the cable chain yet because I didnt know the size I would need.

20221016_153501_compress8.jpg

Also soldered on the connectors on the controller side of the cables and made the cable for the THC.
Its Lapp Licy 4x0.25mm2 for the switches and thc and 4x0.75mm2 for the steppers.
Shielded obviously.

20221016_181343_compress90.jpg

Here you can see the way I handle the shielding towards ground.
Just folded the shield back and taped it down, after soldering I used some electrical tape over the 4 solder joints and then mounted the housing.
Obviously I checked for a good connection and shorts after putting it all together.

20221016_173056_compress99.jpg

20221016_173326_compress37.jpg

Getting close to movement now but still need to order some parts.

[djreiswig]

You could use socket head capscrews in the opposite direction to get some more clearance.

They do not have the clearance the other way around especially with a washer.
Second issue would be getting an Allen key in there.
It still works fine I am just lacking some extra adjustment.

I was referring to the bolts in your first picture, not the ones that you had to cut the heads off of. It looks like you would have plenty of room for a wrench.

[adbuch]

You are making great progress with your build. Keep us posted and I will look forward to seeing updates as you go.
David

[acourtjester]

You do know they make button head allen bolts that are low profile for locations where the clearance is tight. Also heat shrink tubing works better than electrical tape, won't get gooey in time.

a button head.JPG

[TJS]

Great build. I did the same mistake with my water table. Angle like a picture frame and a full sheet welded to the bottom. Worst design ever. Talk about warping. Someday I will do a stainless sheet bent up in the corners like the OP did and be done with it.

[Plasma-art]

I was referring to the bolts in your first picture, not the ones that you had to cut the heads off of. It looks like you would have plenty of room for a wrench.

You do know they make button head allen bolts that are low profile for locations where the clearance is tight.

Probably should have highlighted the issue a bit better.
Its these m5 nuts, there is about 3mm between rail and carriage.
In the v2 version I extended the plate another inch so there would be more engagement for the belt.
Also put the idler pulley holes closer together on that version.
Can't mount the stepper and then put the carriage on the rails otherwise it might have worked.
The vertical support tubes are welded to the rail tubes.

20221017_205457.jpg

20221017_205416.jpg

Also heat shrink tubing works better than electrical tape, won't get gooey in time.

It's getting heat shrink tubing, used electrical tape because it's a bit thinner and the cable was a tight fit through the hole of the housing.
It's there so there so the shielding stayed in place and didnt get squished into the connector.
The only reason I didnt put it over the cable is that I didnt want to cut the loom apart and I forgot to put it on there before soldering the connectors
With the solder joints I tried it with heat shrink tubing but could not get it to fit at all, it was a little to thick.

You are making great progress with your build.

Thanks
Good planning and getting almost everything ordered up before hand helps alot.
I hate working on a project and needing to stop half way because I am missing a certain part.

. Someday I will do a stainless sheet bent up in the corners like the OP did and be done with it.

Who said I used stainless, its mild steel because Its cheaper and I know I am going to be upgrading to a bigger table in about a year if my business takes off
That table is going to be getting a stainless steel waterbed and slat holders.
But getting one bent up is really the best way to go.

[adbuch]

You do know they make button head allen bolts that are low profile for locations where the clearance is tight. Also heat shrink tubing works better than electrical tape, won't get gooey in time.
a button head.JPG

Tom - those are both great suggestions! I keep an assortment of ssbhshcs (stainless steel button head socket head cap screws) as well as the same in black. They come in very handy. In the past I have also had occasion to grind down the heads on regular socket head cap screws for clearance. Yes - heat shrink is most definitely the way to go as well.
David

[adbuch]

Great build. I did the same mistake with my water table. Angle like a picture frame and a full sheet welded to the bottom. Worst design ever. Talk about warping. Someday I will do a stainless sheet bent up in the corners like the OP did and be done with it.

TJ - I used the same technique as you for my water tray - flat bottom plus 4 sides all welded together. I made mine from 11 ga. (1/8") cold rolled steel. It came out pretty well, with only a slight bow in the center - which actually helps the water to run of to the sides when drained. However, I have never drained it - the water evaporates so fast that if I leave it for a month in the summer - it will "drain" on its own. At the time, I was interested in using a thinner gauge stainless steel - but it was just too expensive - around $300 as compared to under $100 for the steel material. But I have no regrets about the method I used for construction.

David

https://photos.app.goo.gl/h8LHufi6frttfGNQA

20170713_225900.jpg

[djreiswig]

Probably should have highlighted the issue a bit better.
Its these m5 nuts, there is about 3mm between rail and carriage.

Ahh. I completely missed those bolts. I was looking at the larger ones.

[Plasma-art]

been sick so almost no progress, thank you influenza
have been working on the secondary BOB i want for my build.
shouldn't have an issue with input pins for a while if i didn't mess up my schematic.
i wish i had someone with a little bit more knowledge about electronics check my schematic but thats how it goes sometimes.
sent the files out for PCB manufacturing so should have the first prototype in a couple weeks.
tempted to design a secondary board with all the circuitry for proximity switches that connects to the next revision of this board.

parport input2 v0.1.jpg

parport input v0.1.jpg

Ahh. I completely missed those bolts. I was looking at the larger ones.

yeah i figured people would have missed that.
sometimes its a bit hard to explain things when english isn't your native language but thats where pictures are for right?

[djreiswig]

Why did you opt to go with a parallel port? Kind of old technology. And kind of limited on I/O.

[Plasma-art]

Why did you opt to go with a parallel port? Kind of old technology. And kind of limited on I/O.

Because i had a computer lying around doing nothing that was suitable and the mesa ethernet cards are never in stock.
Solved the lack of I/O part with that extra breakoutboard.

[acourtjester]

Sometime you got to do with what you can get. The UCCNC controller board couples with Parallel communication ports but connects to the PC via ether, of USB.