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  #21  
Old 05-26-2010, 11:50 PM
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camdigger camdigger is offline
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Originally Posted by TriHonu View Post


What is the advantage of having it horizontal?
99% of the work these mobile rigs need the spool fixture for is piping. Most of the pipe fittings - including the flanges - have integral stubs to match up to what ever it mates to. Tacking up on a horizontal rig like that allows the work to be rolled while the weldor runs his rod to keep the weld pool at the optimum spot on the work circumference. This turns a weld on round work to a butt weld where the work moves past the end of the rod rather than trying to hang a bead on a horizontal groove on a vertical surface. much easier to have all at the same height if you're fabbing up a piping section with a flange at both ends and a tee in the middle, for example -one set up, two or four welds - depending on the required flange-to-flange measurement, all at the optimum height for comfortable welding. A two roller stand is often used to support the outboard end if the assembly gets too long....
The first picture is a piece being held this way to weld a square block on the end of a rod. The second picture is my "get'er done" rotator in a vise with the work tacked to the face plate, and the ground flag tacked to the end to the work. Some time after this picture was taken, I moved the ground to the end of the shaft by welding the 3/4" nut to the end of the rotating shaft and putting the flag on the bolt run into the nut to eliminate having to tack the nut for the ground to the work.... BTW, total cost of my doodad $15 for the bearings all else came out of "inventory"
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Last edited by camdigger; 05-27-2010 at 12:04 AM.
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  #22  
Old 05-27-2010, 07:01 AM
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Originally Posted by Pyro J View Post
Would it work to isolate at the swivel bolt with a plastic tube on the bolt and a plastic washer on each side of the grounding lever?
I still think borrowing the ass end of a starter is easy...the brush holders are already insulated from ground.
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  #23  
Old 05-27-2010, 09:18 AM
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Originally Posted by Pyro J View Post
Would it work to isolate at the swivel bolt with a plastic tube on the bolt and a plastic washer on each side of the grounding lever?
Ding Ding Ding! Thanks for that idea. I didn't see that quick solution last night (Too late to think straight). I went out and turned down a piece of fiberglass rod and made a tapered pin. I added two plastic washers (Pic 1). I cleaned up my ground clamp and the meter now reads 0.0 ohms between the ground clamp and table top. The bearing is still energized so if the clamp swings over and touches the stand current will still flow through the bearing.

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Originally Posted by camdigger View Post
... while the weldor runs his rod to keep the weld pool at the optimum spot on the work circumference. ... A two roller stand is often used to support the outboard end if the assembly gets too long....
Yep, puddle control and long pieces, got it.

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Originally Posted by Ironman View Post
I still think borrowing the ass end of a starter is easy...the brush holders are already insulated from ground.
I agree that the brush holders would work well. I didn't have one available and the stuff I used was already in my shop stock. So I just used what I had available.
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  #24  
Old 05-27-2010, 05:44 PM
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Most of the weldors that I worked around had a rig somewhat similar to what camtrac has shown in his second picture.The main difference is that none of them used bearings at all. They consisted of a piece of pipe with a vertical "fin" welded to the bottom of it for clamping in the vise on the back of the welding rig.The slotted piece of flat plate for bolting pipe/valve flanges to, was welded to the end of a second piece of pipe which would fit snugly inside the first one, and still rotate easily.The ground clamp was usually tack welded to the rig deck, or clamped on anything of the right size (deck was grounded to the project through the vise).The setup was welded together to ensure that the slotted plate was at a true 90 degree angle to the pipe, and in use, the whole thing could be adjusted to be perpendicular, and squares or levels used to ensure the pipe spool being welded up was true (flanges were two-holed, with a level laid across the bolts).
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  #25  
Old 05-28-2010, 07:34 PM
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Pyro's suggestion would have been mine as well. But as usual I am a day late and a dollar short
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  #26  
Old 06-09-2010, 03:39 AM
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Quote:
Originally Posted by TriHonu View Post
My wife swears I now have Adult Attention Deficit Disorder. I just tell her that my brain is now free to wander. But I do tend to jump from one project to another, maybe I just get bored easily.


That would explain why I am now single......
Just means I get to spend more time out in the shop
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  #27  
Old 04-04-2014, 01:05 PM
moroeder moroeder is offline
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Default Welding rotary table great concept but?

I've had a similar build desire in the back of my mind for a few years now. Nothing worse than trying to weld tubing and keeping the part moving, especially with aluminum. However I just had to add one thing that should be done to improve the welding process.

Yes you can ground right through the ball bearings and it may appear your ground provides an adequate circuit for the job. But while I'm TIG welding I notice even the slightest change in grounding circuit quality. Arc cone shape and heat penetration will degrade as the circuit weakens/ strengthens. The problem with the balls being the conductors will create erratic circuit resistance current fluctuations. Although small and mostly hidden from the MIG and Stick processes, TIG will be affected to a noticeable level. Especially with some of the newer solid state variable frequency, square wave, etc. TIG welders.

The rule of thumb I learned from a Purdue graduate in electrical rotating machinery was plan on passing current through copper conductors at a rate of no more than 100 amps per square inch of carbon brush surface area. When I get around to it I will be building a similar welding table with possibly an adjustable vertical/ horizontal work holding orientation. But be assured I will be using a carbon brush to copper ring grounding circuit because most of my work is in TIG and I don't like fighting a changing weld process.
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  #28  
Old 04-04-2014, 01:22 PM
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Originally Posted by moroeder View Post
The rule of thumb I learned from a Purdue graduate in electrical rotating machinery was plan on passing current through copper conductors at a rate of no more than 100 amps per square inch of carbon brush surface area. .
Use a copper sintered brush.....no resistance (or enough to worry about)
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  #29  
Old 04-22-2014, 08:58 AM
CarterKraft CarterKraft is offline
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I have always liked the copper ground strap wrapped 180* around the pipe and held in tension with a spring. Plenty of surface area that way with no fancy parts to make or aquire.

Nice line boring rig too!
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