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my diy plasma table

Share and learn with other DIY members who have built their own plasma tables and accessories.
Wadzii
Posts: 23
Joined: Sat Apr 16, 2016 11:21 am

my diy plasma table

Postby Wadzii » Sat Jun 18, 2016 5:43 pm

We started off with the plans posted on instructables but we needed to ability to use 4x8 sheet so we simply scaled up the design.. well that was a bad idea.

http://www.instructables.com/id/CNC-Plasma-Table/

The belt drive is probably ok for a very small table, but when we scaled it up there was so much slop in the belt drive that the thing was worthless.

I put turnbuckles on the belt to try and tighten it more but ended up just bending stuff and it never got any better. The other issue I had with this design was the plate the torch mounted to had tons of slop, it was just bad all the way around.

This is it with the belt drive and all before we put the water table and supports in

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This is how it sits now. We got rid of the belt drive and modified the rack and pinion drive that http://www.cncrouterparts.com/ sells

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I rebuilt the Z axis with some 8020 extrusion and used my 3d printer to make the torch holder and shaft coupler.

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for my z axis, the coupler is 3d printed, the part attached to the motor uses a set screw to hold it to the motor shaft, then to make sure the "Fingers" dont break off there is a 10-32 screw down each one. For the coupler attached to the acme screw, the coupler piece is threaded to screw onto the acme rod then I printed a jam nut to keep it from spinning. I didnt have much luck with a set screw there, the jam nut works perfectly.

In the red "bearing block" I have a small piece that threads onto the acme rod, that is just loctited into place. It fits inside the bearing block with the "lid" held on by zip ties. That holds the acme rod up.

The lower torch holder piece is threaded to accept the acme rod, that's what drives the z up and down. I have a bit of tig wire hose clamped to the torch and bent down to act as the ohmic probe. The next modifications will be to build a floating Z into the torch holder, the ohmic works great using the shield with the 45a consumables, but the 30a require the probe rod which bends out of the way pretty easily and requires a very watchful eye to keep from breaking things.

We were able to use the table with the belt drive to cut the pieces we needed to change over to the rack and pinion. We had to make new holders for the square steel tube because we needed it held at a different angle, the 1/4'" thick plates that hold the cncrouterparts carriages together were also cut with the belt drive. They all took a ton of hand fitting with grinders, etc to make work. the long belts had probably 0.050" worth of backlash, the short belt had probably 0.030".

I'm using the $25 sainsmart break out boards off amazon, $25 nema23 motors also from amazon. The stepper drivers are cheapo's off ebay. I'm also using a proma thc150. I'm also using a russian ohmic sensor, I originally had it wired directly to the break out board, but after frying a few I figured we needed something to protect the board from the plasma voltage.

http://www.ebay.com/itm/321846429622?_t ... EBIDX%3AIT

Currently I'm using mach3 with a uc100 motion controller, but that will be changed over to a UC400eth and UCCNC next week so that I'll have enough inputs to wire in all the homing switches and limit switches.

This is my first experience with anything along these lines. We pretty much went into this knowing absolutely nothing about linear motion, cnc controls, any of it. My shop is a high performance auto shop, this was built so that we could bring some of our production in house and make custom parts quicker.

tubby
Posts: 10
Joined: Sun Jun 05, 2016 11:02 pm

Re: my diy plasma table

Postby tubby » Sat Jun 18, 2016 11:12 pm

I built this also from the plans on instructables.
And while it's a good cheap design for a small table it doesn't scale very well.
I've never managed to get the slop out of it and am now in the process of building a new one from precision plasma parts.

Good luck with it and post up if you get it dialed in

Wadzii
Posts: 23
Joined: Sat Apr 16, 2016 11:21 am

Re: my diy plasma table

Postby Wadzii » Mon Jun 20, 2016 11:12 am

Are you using their floating torch mount? I 3d printed one I designed up but its not a solid and doesnt move as freely as I'd like.

The precision plasma torch mount looks like it'd work pretty well and I can easily adapt that to my z axis.

I've got the thing working very well, with the 30a consumables the ohmic sensor doesnt work well.

I can move at over 500inch/min with very high acceleration and not loose any steps. My table isnt ridged enough to move that fast though. The square tube I used is 14ga wall and the end brackets at 14ga as well. I wish I'd made it from stiffer material.

Johnnybravo
Posts: 39
Joined: Fri Oct 17, 2014 10:35 pm

Re: my diy plasma table

Postby Johnnybravo » Wed Jul 20, 2016 12:25 pm

MAN!!! I'm so glad I read this! you all have addressed some issues I will be looking at soon! Thanks for posting!
Eagle Plasma 4x4
Hypertherm Powermax 45
Miller Maxstar 150 SL
Corel draw 7, Inkscape, Qcad, Sheetcam, Mach 3

Wadzii
Posts: 23
Joined: Sat Apr 16, 2016 11:21 am

Re: my diy plasma table

Postby Wadzii » Wed May 24, 2017 3:24 pm

Just wanted to update this.. We've been doing production on this thing for a year now with no major issues. I did switch from Mach3 to UCCNC and their uc400, its far more reliable than mach 3 along with having a plasma specific version of the software which is nice. I do keep spare drivers and motors here just in case (it is all Chinese!) but so far they have served me well.

When something does break I'll be rebuilding the gantry from aluminum extrusion to make it lighter and putting more powerful motors on it so I can run it a bit faster. With thin metal I have turn the plasma cutter down and go a little slower or it'll loose a step or 2.


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