home-made weld positioner or plasma circle cutter

I made a weld positioner for doing circular tig welds. By mounting a pivoting arm on the base, I find that it works really well for cutting circles with the plasma cutter. Cost of the postioner was zero, all from junk under the bench. Power for the positioner is a small variable speed Makita cordless drill.

Here I have cut a couple of 18" discs (both at once with the little Power Ultra 205 multi)for a custom drum I have to build. The drum will go into a new machine being built for a large bakery somewhere in Salt Lake City.

Here is a link to a video clip of the cut http://www.youtube.com/watch?v=iI0qbNjLCHs

Looks like 28 amps is the setting showing there, not bad for cutting 2 at once (3/16" ea.) which is much tougher than a single thickness of 3/8".

Glen

Very good, I like it , you remind me of me.

Any more pictures of the components, that works sweet and I am interested in building one for myself. Thanks

I captured the pics so I could reference them later, what we need is a picture of the gearing you used.

I think I'm seeing a power window track there for the gear down. if that's not what you used, a power window mechanism/motor and a rubber drive wheel should work just fine.

I'll take some pictures of the unit tomorrow and post them. I used an old gear reducer and a small part of the remains of a burned out electric garage door opener.

Here is a link to another video clip that shows the postioner a bit better. http://www.youtube.com/watch?v=av-aIMH-iFQ

The flat vertically mounted silver plate is the bottom out of an old garage door opener. I used it for the spindle since the other end of the spindle already had a sprocket of the correct pitch on it. The nylon gear is just along for the ride.
The cordless drill just gets chucked onto the spindle and then activated by pushing the handle down so that it engages the bolt(ground the head roundish) you see me turn a little bit to change speed. Turning the bolt in and out varies the speed by pushing/releasing the trigger. The gear reducer is a right angle 40 to one unit. The sprockets give another 4 to one, so 160 to one is the total reduction after the drill.

How do you attach the ground?

I just clamp to the table and let it go around with the object being cut or welded. Sometimes I have to stop at about 3/4 the way around and reposition the clamp, not a big deal for the way I use the rig.
Expensive weld positioners use weld brushes on the pivot shaft for the ground, probably a good idea if you are using a weld positioner day in and day out.

Thats a pretty swwet bit of back yard engineering. My kinda thought process. Hope you dont mind some of us Borrowing your idea!

not a bit, that's why I put it on here. I think it's great when old clutter under the bench can be made into something useful.

Glen

Nice work good to see that people still have that bit of creativity left in them. This is just the reason I keep all the treasures ( junk the wife thinks) that I find.

great work Worntorn, I have a similar set-up that I use with a cutting torch I used a Power wheelchair motor with a gearbox that was set up for 24v and just run it at 12v Off a small power supply. it runs about the same speed yours shows and works great. I took the tire off the wheel then mounted a plate to the wheel as my cutting base with the torch set up I dont have to worry about ground but once I get my plasma cutter I will probably have to make a brush set up like your talking about.

thanks Don

With the variable speed on the drill the rpm of the plate can be adjusted from almost zero to a max of 15RPM and anything in between.
The bolt that the speed trigger rests against is the adjuster, it can be threaded in and out easily with index finger and thumb.

Looks like I may be using it quite a bit, I have another custom feed wheel to build for the Bakery Equipment Supply company.

Glen

yea I cant wait for my 250ex to arrive I have a few projects that I will put it to good use on. Yours is definitely more adjustable but I just use mone to cut out the round sides for smoker bbq's was making . got a bunch of freebie food grade steel drums and had to make my own fire boxes for the coals and the smoke wood. They worked out great while I had em. outta drums and the ones that have oil or other chemicals and such cant be used cause you have to heat them so hot to burn out any residue and I don't have that capability. wouldn't want to poison anyone. I got 4 people waiting on me to make them extended drag swing arms, good coin there and I also have a Pucati 999r that I need to tear down and make a frame jig and Ill be making a new frame in Titanium. should drop some weight from the stock steel trestle frame.

The red parts will all be redone in titanium at some point

Attachment 1303

so many projects so little time LOL.

why don't you use one of these and ground the shaft?
http://i.ebayimg.com/00/$(KGrHqMOKjc..._id=880000500F
attach it to a bolt on one end and put a spring on the other so it holds tension against the shaft, then just hook your plasma/tig ground to the bolted down end?

I can't remember where I have seen this, but I have used it a couple times when welding broken shafts back together in a lathe, works great

Brilliant! I have a 90 degree gearbox that I've wanted to set up as a positioner for tubing-type work. I gave up un the project a while back becuasa I didn't have a cheap easy way to drive the thing. It just so happends nthat I have a coulpe of cordless drills with dead batterys laying around. I will be starting a thread on powering them, up with regular AC. Thnaks!!

Thats a really good Idea using a variable speed drill connected to a gear box, I think I'm going to borrow that. Thanks

no problem.

I use the little weld positioner all of the time now. It gets used roughly 50/50 for welding and plasma. I built it with welding in mind, but the addition of the pivoting arm made it quite useful for cutting circles or part circles with the plasma cutter.

Next I added an steady rest for the forearms to lay on when tig welding. This is just a 10" long block of 2x 10 placed on edge and fastened along the side of the metal base plate. The block sits about 1/2" from the turntable at the closest point.

I just realized that you can see the block in the video, guess it was already on there when I filmed that.

Anyway, in case anyone wondered, that is what that wooden block is for!

ScratchStart, good idea, I 'll give that a try.
Most of the time just clamping the ground to the turntable works fine, but once in awhile I'm doing something where it gets in the way.
Glen

I really need to build something like this. It will save me tons of time cutting circles out of 3/8 steel for hubs.

It didn't take long to build, started in the morning and was playing with it in the afternoon. I already had all of the necessary bits on hand, that helped.

If you have any questions on how to build it or what to use, just ask away , be glad to help.

Glen

If I could interject a thought, a friend set up a gas cutter for cutting 2in steel and used a treadmill motor being it's a variable speed motor setup anyway and he has used it for a couple of years. Works fine for him.