Homemade CNC Torch

[accuratemike]

I built this CNC Oxy/Acetylene torch table to do small runs of brackets.
It has a 30"x30" capacity and uses an un-modified hand torch (Victor Advantage II 250)

This shows the 24v solenoid and air cylinder that pushes the button. I use pin 8 and coolant A on/off to trigger the button in TurboCNC.

This shows the torch cutting parts for itself. This is the "Comb" that holds the work supporting "bed". I posted more info here: page 5 of Sanghera's post
It was (relatively) cheap ($1200, including torch & computer) and fun to build. I am using 187oz 23's, Xylotex drive, TurboCNC, 30v and get 106ipm rapids. It cuts 3/16" @ 49.5ipm. Just another way to skin a cat. Enjoy, MIKE

[WeCheat]

Good looking setup. Was the use of the bearings for the slides because you had them or for ease of construction?

[accuratemike]

Cost, performance, but probably not ease. A cam follower can be $17. I looked at various machines using cam followers or bearings and decided there had to be a better, cheaper, way. Ball transfers seemed to be it. I didn't have to fab axles and brackets (skate or other bearings), and they were 1/3 the cost of mounted cam followers. It was a little tedious to bore the holes, that the balls pass through, in the angle. If you want them all to hit together, precision was paramount. I was able to bore the 16 holes in the angle, and they do all hit. Actually, precision machining and welding was the only "hard" part about building it. The table and gantry had to square and level, The balls all had to be mounted exactly the same. An adjustable, bolted, solution would have saved time but, added expense. I have more time than money. The ratio of set-up to welding time was probably 10:1. Proof is in the pudding, and it works really well, MIKE

[mvaughn]

Do you have any close-up pictures of items that you have cut? I'm curious about how the cut edges turn out.

[accuratemike]

Here are a few of the letter M (3" high). This isn't what I do with it, but I had it laying here.

This is an edge. Little fuzzy, but you get the idea. Main thing is that I am using a sander (with dust collection) instead of an angle grinder to finish them up. This hasn't been hit yet. I did rub it on the floor to get a few slag pimples off of the bottom.
Here is the letter M

These pics end up being about 70% larger than life on my monitor (800x600) You can see the kerf in the tips of the inside of the M. It is about .050" with a 00 tip. I have a 000, but haven't tried it. Should be about .030-.040". Since these were cut I have increased my feed rate from 30.5 to 49.5ipm. I had stopped at 30ipm previously because the torch's manual said that was the high end. I have done some testing since then, and can run 49.5 without blow outs. I also bumped up my accel and, am running off of C instead of A now. This helped a ton at minimizing pauses. This makes outside corners alot sharper. It will do holes, as long as they are big enough for some lead-in. I'm still learning. I am making chassis and suspension brackets for a tube frame trail buggy. They are bigger and less complex. It works very well for it's intended purpose. (Something cleaner/better than hand-torching) MIKE

[mvaughn]

Very nice work, Mike.

[accuratemike]

Thanks ! Especially when you consider that I had never even seen a CNC machine before building it. I started reading up, on the web, in January. I bought my first parts in March. I've had it running since October. It worked fine on the first cut. And I didn't follow the norms as far as concept or common practice. It could have been a huge (expensive) flop. My feet were a foot off of the floor when it first ran. I didn't turn a stepper untill 5 minutes before I started using it. I have never seen tube, ball transfers or air-operated button, used before. Another oddity is running the screws over the top. I had seen it done, but not on a metal torch machine.
http://groups.yahoo.com/group/Xylotex/message/2493
http://groups.yahoo.com/group/turbocnc/message/10451
http://groups.yahoo.com/group/DIY-CNC/message/6821
http://groups.yahoo.com/group/DIY-CNC/message/7387
http://www.pirate4x4.com/forum/showthread.php?t=293058
These are a few of the other threads I started (if anybody is really that interested). I am working on an unconventional desktop router project now. I may even have an eye twords re-sale on it. The labor invested in the torch precludes my building them for others. But, I am working on a more feasable small router design that I may be able to market. BTW, I looked at all of your project's pages as well. My hat is also off to you. MIKE

[mvaughn]

Thanks for the kind words about my project. I hope it works when I finally get er done.

I've been trying to understand how the bearings on your machine work, but I've never seen anything like them or can't make them out. Can you tell me a little about them?

[accuratemike]

They are ball transfer bearings. A 3/4" steel ball in a cup with 80 little balls. They are used various ways. Sometimes as feet on equipment and furniture, mostly mounted ball-up in conveyors. Here are some of McMaster's pics of them:





It was the last one that caught my eye. I had sold pipe storage rack that used that system at an earlier job. This is where the impetus came from.


The type I used

Loaded, they have zero play and each supports something like 80#. There are little oil holes in them, and I blow air through these, followed up by some light oil. The tubes were polished with oil and sandpaper. Those are the straightest sections selected from about 80' of tube. Luckily I have a ton of it around from the tube frame project. The end plates for the gantry were made on the mill, with careful attention to the centerline distance. The notched tubes for the table were welded together, before being birdmouthed in the mill, to insure equal length. I used a 1 1/2" roughing endmill to notch the tubes. It rolls along pretty nicely. MIKE

[accuratemike]

Originally Posted by accuratemike http://groupyahoo.com/group/Xylotex/message/2493 http://groupyahoo.com/group/turbocnc/message/10451 http://groupyahoo.com/group/DIY-CNC/message/6821 http://groupyahoo.com/group/DIY-CNC/message/7387 http://www.pirate4x4.com/forum/showthread.php?t=293058 These are a few of the other threads I started (if anybody is really that interested).

Thats groups.yahoo , the link busting machine keeps making it hard to link to the "other guys"

[gkpwelder@yahoo]

accuratemike your table cool is there anyway i could get plans to build one for myself pls thankyou gkpwelder@yahoo

[accuratemike]

Thanks! There was no plan. I actually started with a pile of parts and built the table around the torch and lead screws. Everything kind of dictated where everything else had to go. You can glean almost all of the information from the groups and posts listed. It has been a few years now, I have probably forgotten as much as I remember. It is still working (well). I did put some pictures here: http://www.accuratepower.com/Torch and something I made with it here: http://www.accuratepower.com/Rest . Good luck, I'd just look at the pictures and improvise. Enjoy, MIKE