CNC Plasma Cutting in a Small Space

Many home or small shop based fabricators would like to have a 4' x 8' or larger CNC plasma table, but lack the space for it. Yet, there is no need to deny ones self this fabulous process just because you don't have an ideal location for it.

I solved this problem for myself years ago by building a 2' x 2' table on casters. I simply rolled it outside my garage to use it, and the plasma dust and smoke issue went away too. More recently I put together a similar sized machine the sits under my deck just outside my basement door. The compressor, plasma cutter, and computer are just inside the door 10 feet away. It takes about 5 minutes to hook up the cables and torch for use.

I have found that there are virtually no shapes I want to cut that don't fit within the travel limits of the two axes. Also, there is no need for a torch height control on a machine of this size. I have one, but use a Bugo rack and pinion machine torch holder instead.

The first photo is of my original, and the second of my current machine. I have also includes photos of a few shapes cut with the latter table.

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Thanks tmate3! We've added your Compact CNC Plasma Table to our CNC category,
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<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-compact-cnc-plasma-table"> <img src="/uploads/242047/homemade-compact-cnc-plasma-table.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-compact-cnc-plasma-table">Compact CNC Plasma Table</a> <span> by <a href="https://www.homemadetools.net/builder/tmate3">tmate3</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/cnc'>CNC</a>, <a href='https://www.homemadetools.net/tag/plasma'>plasma</a>, <a href='https://www.homemadetools.net/tag/casters'>caster(s)</a> </div> </div> </div> </div>
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Neat. I built a 4x8 single arm gantry (supported only from one side) years ago. Does the crud gum up your linear bearings?

Nice job! What are you using for software and hardware to run the g-code? Arduino? GRBL?

My first machine build 25 years ago was a single (cantilevered) arm unit. I used the weights out of a grandfather clock to eliminate the backlash (removed for this picture).

On this machine the Origa (Parker) linear cassettes have wipers that keep the rails clean. Never had any problems from dirt or crud. I do wipe down the rails each time I get ready to use the machine.

I am using FlashcutCNC electronics and software to run the machine. I use CorelDraw to create the shapes and save them as DXF files, which the Flashcut software imports and converts to G code. My former company worked with Flashcut for years, so I am quite comfortable with their stuff.

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Originally Posted by tmate3

I am using FlashcutCNC electronics and software to run the machine.

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Have you considered LinuxCNC? It's a freebie and is very powerful.

At this point I am retired, and just do the CNC stuff for my own enjoyment. Thanks for the suggestion though.

Thank you tmate3. I need to do the same. Thanks for making the plans available

Might you possibly have plans or at least additional 'build' photos to share? I'd really like to build something similar and would appreciate any additional details to accelerate the possibility. THANKS!

I'll see what I can scrounge up in the way of build photos.

Hi tmate3
I also would appreciate any additional details you could supply on your Plasma Table. Are you using rake and pinion for axis movement?
Thank you
Willy

Here is some more detail on the above table:

I used a 2' x 3' shop table from Rocklers as the basis for the table. https://www.rockler.com/rockler-24-x-36-shop-stand
It is very sturdy, and the perfect size for the project. It comes with a set of adjustable feet.

Attachment 37995

I drilled out the holes in the top of the table frame (end holes) to 1/4" to accept button head cap screws. Situated on top of the Rockler table will be for lengths of part# 2020 aluminum extrusions from the 8020 Company. The two end pieces are 30 1/2" long. The two side pieces are 36" long.The side pieces are secured on top of the end pieces using eight 8 hole corner brackets from 8020. Four of the brackets are on top and can be partially seen here. Another four are underneath and can't be seen in the photo.

Attachment 37996

To be continued .....

The machine uses Origa (Parker) linear rails and cassettes to both support and guide both axes. The non-driven end of the Y axis rides on, but is not guided by a length of 2" x 1/4" cold roll steel bar. On the subject of being driven on only one side of the X axis -- with a machine this size, there is no reason to have the cost and complexity of a second X axis motor, circuit board, wiring, etc.

The photo below shows the different sizes of Origa slides and cassettes. I used the FD-25 size in my table, but you could probably use FD-20 with some minor changes to the brackets. Both the linear rails on my machine are 26" long. There are two gear racks that are each 22" long. The actual maximum travel distance for each axis is 22". The spur gears will run off the ends of the gear racks before the cassettes reach the ends of the rails. This avoids the necessity of using limit switches.

You will need two spur gears (20 pitch, 15 tooth, 5/16" ID 20 deg. pressure angle). I used gears with set screws, although you can knurl the shafts and press them on if you prefer. The spur gears and gear rack can be purchased on eBay from the seller CAROLBRENT.

Attachment 37997 Attachment 37998

A 32" long 8020 extrusion serves as the gantry, with a linear rail on its side and a gear rack on its top. This top rail and its roller cassette make up the Y axis. The other rail goes on the side of one of the 36" 8020 extrusions. This is the X axis. The X axis gear rack goes on the outside of it 36" 8020 extrusion. The photos below should give you an idea of how these components work together.

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to be continued .....

You will need two 4" long pieces of 5/16" diameter drill rod. 5/16" dowel pins would work if you could find them 4" long. The spur gears must be mounted on the end of the drill rods as shown.

You will not use the existing holes in the gear rack. Instead, drill three 1/4" diameter holes 1/2" in from the non-toothed side of the rack. Place them about 1 1/2" from each end, and one in the center.

Attachment 38015 Attachment 38016 Attachment 38017


You will make two brackets using 4" lengths of 7" x 2" x 3/8" thick angle iron. You will need to cut the 2" leg of the angle iron down from a longer leg. Study the diagram of how the parts all go together to understand the logic of the chamfered holes, studs, etc.

Note that on the x axis bracket the two 3/8" holes shown along the center line are to accommodate your rack and pinion torch holder. They should be drilled as a final step and located to suit your torch holder. I located mine near the top.

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to be continued .....

Two identical motor mount brackets will be fabricated. If you had the use of the little CNC machine, they could be produced in less than 4 minutes. As it is, you will have to do it the old fashioned way. You could hand cut them with a plasma cutter and grind them smooth. I made two machines, so the brackets you see here were cut with the first machine.

The first shot shows the bracket after being cut. Incidentally, you do have to tap off a slight dross after cutting -- nothing like a hand cut piece, though. The last shot shows the same bracket after a flanged 1 3/8" long drill bushing has been welded in place. The drill bushing has a 3/4" OD and a 1/2" ID. The beauty of using the flanged bushing is that when clamped against the plate, you are assured that it is perfectly perpendicular. A couple of good tack welds are all that is necessary. When it has cooled down, press a flanged 1/2" OD x 5/16 ID x 3/8" long oil impregnated bushing into both ends of the drill bushing. The oil impregnated bushing MSC part number is 06454466 (currently $8.05 for a package of 5). The drill bushings can be found on eBay. If you can't find them 1 3/8" long, as I did, 1" or 1 1/4" long can be substituted. Motor mount brackets are 3/16" steel. I bought a length of 3/16" x 4" cold roll bar from On-Line Metals to make the first machine. I made two identical machines, one of which I keep inside to experiment with new attachments, accessories, etc. I used the first machine to cut the brackets for the second machine from 3/16" hot roll plate. Both the X and Y axis motor mount brackets are identical.

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to be continued .....

You will need two large timing pulleys (48 XL 5/16" ID), two small timing pulleys (14XL 1/4" ID), and two timing belts (120XL). These are all readily available from MSC, McMaster-Carr, and other industrial supply houses. Non name brand equivalents can be found on eBay.

This will all fit together as shown in a couple of previous pictures, and here again. Note that the X axis gear rack is fitted upside down and attached to the upper channel in the 8020 extrusion. This reduces the amount of plasma dust that can settle into the gear rack teeth.

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The Origa/Parker linear rails consist of four hardened stainless steel rails embedded in an aluminum bar as shown in the photo below. The mounting holes for the FD25 rails accept 1/4" socket head cap screws, and are pocketed so the screw heads are beneath the surface of the bar.

The gantry is simply a 32" long 2" x 2" 8020 extrusion, the same as the others. One end will have four 1/4-20 holes tapped into its end to accommodate the end support bracket, which is pictured below. I cut both of my linear rails to 26" which, allowing for the width of the cassette, gives me 21" of travel on both axes. As I mentioned before, this could be increased slightly on the X axis, but the Rockler table width of 24" limits the length of Y axis travel that is possible.

The cam follower has the following MSC part number: 92610583. They can be found for a fraction of the MSC price on eBay.

I believe this provides most of the information needed to build a little machine like mine. I hope it proves helpful if you decide to undertake the project. Other than fabricating the five brackets, the rest of the work could probably be completed in a couple of hours -- mainly just cutting some things to length, drilling a few holes and bolting things together. We dealt with the physical table here, and the electronics and software are something you will have to research independently. Depending on your budget, you can get anything up to and including a turn-key electronics/software package with motors that will bolt right up to the above motor mount brackets.

If anyone has further questions regarding the table, please don't hesitate to post them here, and I will try to answer them.

Hi tmate3

What an excellent set of instructions/plans. There is allot of information here and I thank you for taking the time to put it all together. Great job. I'm looking forward to starting this project in the near future. Thank you.
Cheers
Willy

Hi tmate3,

Thanks very much for the excellent job presenting your design and build. One question I have is how much backlash to you have in the rack & pinion drive and how have you compensated for it? Thanks again, John

An excellent question, John! When I first got started building these things many years ago, I remember having problems with backlash. Circles wouldn't end up precisely where they started, etc. It ended up being due to the fact that I was using small gear rack, thinking that it would be more precise than larger rack (a fallacy). It had to be tack welded to a piece of 1/2" x 1" cold roll bar to be mounted to the machine. The resulting piece had small bows outward between tacks that caused binding unless I backed out the spur gears slightly. The slop from backing off the spur gears caused some backlash.

We ended up having larger, 20 pitch, 20 degree pressure angle gear rack cut by Moore Gear that had the teeth cut into the cold roll, and the ends dressed so the sections could be butted together. We could then engage the spur gears all the way up to, but not quite to the point of binding. The backlash issue went away. These days you can buy similar gear rack on eBay.

As an example of just how little backlash was present, check out the pictures below. In 2004, I mounted a 65 watt Synrad laser on one of our standard machines. That's not near enough wattage to cut steel, but look at what it did in paper, etc. Plasma arc is not nearly so demanding.

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That's very impressive - you've put my mind at ease wrt backlash concerns. Thanks tmate3!

John

Hi Guys
Have seen designs were the axis drive assembly (Motor, Pulleys, Belt and Spur Gear) had a pivot mount and a spring pulled this assembly (Spur Gear) towards the Rack taking out the backlash. Not sure if this would tend to make the movement jumpy or not? I have zero experience with this arrangement but have seen it used.
Cheers
Willy

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Originally Posted by willyb

Hi Guys
Have seen designs were the axis drive assembly (Motor, Pulleys, Belt and Spur Gear) had a pivot mount and a spring pulled this assembly (Spur Gear) towards the Rack taking out the backlash. Not sure if this would tend to make the movement jumpy or not? I have zero experience with this arrangement but have seen it used.
Cheers
Willy

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Yup. My CNC flame cutter is exactly like this. I had assumed it was so the gears could roll over crud and slag, but you're probably right about reducing backlash as well.

For anyone interested in the beginnings of the Torchmate company, information on its early history can be found here:

https://www.practicalmachinist.com/v...chmate-387482/

Are there any build plans for this wonderful project? I would like to build one for myself.

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Originally Posted by mccwho

Are there any build plans for this wonderful project? I would like to build one for myself.

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I have a pdf file with free plans you can download. While they don't cover the entire project, they do provide a lot more information than is included here.

The plans can be accessed here: https://fortuneafterfifty.godaddysit...c-plasma-table

Quote:

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Originally Posted by tmate3

I have a pdf file with free plans you can download. While they don't cover the entire project, they do provide a lot more information than is included here.

The plans can be accessed here: https://fortuneafterfifty.godaddysit...c-plasma-table

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The link seems to be dead. Is there a new link?

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Originally Posted by Sleykin

The link seems to be dead. Is there a new link?

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Try this one:

https://img1.wsimg.com/blobby/go/667...=1654734029891