A "portable" CNC plasma table

[meincer]

I have limited space in my shop (who doesn't?). So a couple of months ago I got the idea of making a small (roughly 3' X 3') and light weight plasma table that could be moved, put on top of a large sheet of metal and/or over top of my small plasma cutting table.

Well it took me a while but I finished it. I am pleased with its performance(with one exception). I mostly cut 1/8th or thicker and therefore super fast speed was not necessary. Not counting the motors (from automation direct, 278 oz-in) and the driver board (Xylotex, 3 axis) and the software (TurboCNC and SheetCAM) I have under $150 in materials.

I actuate the plasma trigger by a small chain that presses the trigger when the z axis is lowered. The chain holder is spring loaded so going beyond the trigger point won't damage the trigger. After adjustment (easy with threaded height control) this works better than one might think it would.... flawlessly!

I skimped on the x axis linear bearings (skateboard bearings on an aluminum angle). It works adequately but the undriven side sometimes does not follow the driven side without shuddering a bit. I think I might go to two toothed belts driving both sides with the one x axis motor. This is the only performance issue, everything else works great!

The other two axis bearings are simply bronze sleeve bearings on ordinary steel rod, and the threaded rod just standard stuff all from the hardware store.

This setup probably doesn't match the precision of larger, more expensive tables but it does what I want it to.

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[massajamesb]

I like the ingenuity! Good job!

I have seen quite a few of the "hardware store" variety router builds, but this is the first plasma one I have seen. Use what you have, and keep it cheap!

Looks like a winner!

[sailandoar]

That looks like what I will be building........... maybe this year?

[Weldtutor]

Nice work Meincer. Thanks for sharing.

Your post in the "other" forum also caught my attention.

What size threaded rod is used & what travel speeds do you obtain?

For the ingenious trigger activation, does the chain remain in a fixed position, & the torch move against it as mentioned?

You should be able to travel around the neighbourhood doing CNC plasma work!

[meincer]

I really haven't done much travel speed testing. I mostly cut rusted 1/4" to make rustic out door signs. My Hypertherm Powermax 600 works well at around 40 inches/min at that thickness and I have no trouble with that.

I am using standard threaded rod (1/2" for the X and 7/16" for the Y, standard threads/inch, I honestly can't remember the numbers). I just adjusted the scale factors in TurboCNC to get the correct scaling. I haven't really played with microstepping settings, etc.

The chain for the trigger is connected to the fixed backplate of the z axis. The other end is then held by the spring loaded holder, also attached to the fixed part of the z axis. The torch portion is inside of the chain and lowers into the chain when it goes from the 0.15" I have set for off to the 0.05" cutting position. The on/off action is amazing repeatable.

[meincer]

Actually I realize after looking at my own photo that I connected the back end of the chain to the moving portion of the zaxis (NOT the fixed portion) and the other end is connected to the fixed part. This still creates a situation where the torch lowers itself into the chain when it is lowered to the cutting position.

[Weldtutor]

The on/off action is amazing repeatable.

Thanks for the information.

Your table is a marvelous piece of KISS engineering!

WT

[DSL PWR]

Great job! I tend to over do things, and will have some pics of mine in the comming months. If you have an extra digital output go to your local surplus store and find an electric door lock solinoid (out of a car), and use that as a mechanism to trigger your torch. Even if your voltage is a little hi for the solinoid (over 14 vdc) it should work just fine.

[gromit68]

The trigger switch is low voltage, I'm curious as to why you don't just use a control output trigger a small relay to do this job.

[yudmikle]

Thanks for the information.
Good job!

[meincer]

I was aware I could have used a solenoid or a relay. What I ended up doing, though, didn't cost anything (literally NOTHING) and either of the other two solutions cost me something as I didn't have either of these components on hand. I also didn't want to open up my plasma cutter chassis and wire in there or splice wires anywhere else.

Besides......as hard as it is to believe it really works flawlessly!

[JEFFY]

Truley a very nice bit of work. I had something close to this but was smalller. The frame size was about about 20x20 and I would set my plate on a 55 gallon drum that was set up as a cutting table. Then lay the unit on top and cut my parts. Wish I still had this set up. My old employer ended up with it as he owned the plazma cutter and bougth my table when I left the buisness.
I like the way you made yours, very simple. Will have to remember this as I have been thinking about buying my own plasma cutter.

[Dale Heart]

I think you are taking the wrong approach. There is no need to have an actual table, you could have a jib design plasma cutter. There are dozens of companies in China making them and they are full CNC and all you have to do is stick a torch onto the end of the jib.

[BobWarfield]

For those of us who have big garages, but that still do not have enough room for:

- A 4' x 8' router table

- A 4' x 8' plasma table

- The loading dock and forklift needed to feed said 4 x 8 machines with raw material

- A full sized CNC mill or VMC

- A full sized CNC lathe

- A good sized welding table to Tig/Mig all those newly cut parts together

- A decent workbench/worktable

- Rollaway tool chests for all the goodies

- yada, yada, yada

Thank you!

A portable/swing away/doesn't-take-a-lot-of-room-when-not-in-use-plasma table seems like a beautiful thing. And, I would think plasmas are even less sensitive to "hardware store" construction than routers.



Great work,

BW

[chuggins143]

I think you are taking the wrong approach. There is no need to have an actual table, you could have a jib design plasma cutter. There are dozens of companies in China making them and they are full CNC and all you have to do is stick a torch onto the end of the jib.

Ok, I'm gonna sound like a complete newb here (because I am), but what is a jib??

I finally got back on line and found some old digest on an old acct... after looking at this thread it has gotten my creative juices flowing again and motivated me to start back down the diycnc path. I have more than enough materials to build something like what is shown here, at least the rails & gantry portion... actually put together a prototype of a rail with bearings this afternoon.... looks like I'll be buying some steppers, drivers, and such in the future! Looking forward to hanging out at the Zone more.
THX
Chad

[massajamesb]

I think Dale is referring to a portable cnc setup that has a gantry like most optical cutters, wherein there is a XY moveable torch on a gantry that only has bearings and drive motor on one end, versus being supported on both sides and/or driven on both sides. I am not sure though, he speaks of machines available in China, which I am unfamiliar with.

I don't think that he is taking the wrong approach. Much to the opposite, he built a working machine on a budget, and it burns the parts he needs, cheaply and cleanly. His table catches most of the sparks and gives the material support. How can you beat that?

[Weldtutor]

A great project Meincer.
If it works for you, it's the right approach! Positive posts are also the right approach here, when directed toward someone sharing their project with us all.

A jib is sort of like standing with your back stuck to the wall, with your arm (jib) pointing straight out from your shoulder.

Some shop cranes & chain fall hoists use this design. The chain falls roll from end of arm back to point of rotation (shoulder).

[BobWarfield]

The jib idea is fascinating, and no disrespect intended, because the machine pictured is also brilliant. I just want to explore the jib setup a bit though.

I am envisioning a rotating "X" axis about the base, a linear "Y" axis the moves along an arm, and the Z-axis mounted on that arm. Think of it as running on polar coordinates instead of x,y coordinates. It might look something like this sketch:



The sketch shows a 48" arm of 2 x 2 material, perhaps an 80/20 extrusion. The base is an 8" diameter cyliner, and the jib is supported at the end with a downlink. It probably makes sense to run that center shaft up high enough to hold the plasma cable above the fray. There is some engineering needed to make the rotating axis run smooth and true, but it isn't that bad. The Z can ride out the extrusion on a skate bearing arrangement of some sort.

It's an interesting thought, and I suppose given the needs of a plasma system, it could be quite light and doable. One could even imagine a magnetically attachable base.

I'll have to ponder this one further. Need to consider the programming implications on Mach 3 as well. Ideally, you want this to look just like a regular x, Y, Z gantry when programming. I'm pretty sure Mach can do that, though.

Best,

BW

[thkoutsidthebox]

Looking forward to hanging out at the Zone more.
THX
Chad

WELCOME! Dont forget to post a build log.

[chuggins143]

Ah, I get it... for some reason I wasn't making the connection... we have jib cranes out in our shop to lift product with. Thanks for the info!

I will have to post up a pic when I get something "real" built... I was looking at the pics at the first of the thread which got me to thinking... I have a huge supply of 1.5" x .25" aluminum angle at work that we don't use, got to sketching up some ideas and went and threw together a quick prototype of a runner with skate bearings... seemed to work fine. Out of curiosity, what are the disadvantages of using skate bearings? ...what are my other options?

Thanks again for the info and the welcome!

Chad