Dividing Head Welding Positioner Ground Lug Ideas

[Ironken]

Can I buy the divider parts, you not going to use?/

Heck no, you can't buy them! You can have them free, though.

The dividing head in question is incomplete, you are welcome to any parts that I receive that are unused.....probably just the crank and plates. I will let you know what I have left over. It may be a few weeks.

 

[Ironken]

I agree with Bob, seems like using a sledge to kill a mosquito but... RJ has the best idea, starter motor brushes and lots of them around the perimeter.
Me I would try to keep the dividing head functionality also, unless I already had another div head.
Mark
ps here's an idea: maybe fill the unit with graphite powder instead of oil then you wouldn't need brushes at all.

The graphite powder idea kinda threw me, kinda outside the box but cool. There are some huge positioners out there so it's not really overkill. Alot of guys are using a setup similar to this (just grounding thru the chassis and bearings....bad idea) and they work very well. I have a big set of turning rolls and need a bench top setup.

 

[brino]

maybe fill the unit with graphite powder instead of oil then you wouldn't need brushes at all.

Interesting idea, but I wondered if you'd end up with a big mass of sintered graphite inside........

What about turning this inside-out.......once you machine off the degree scale, drill a number of radial holes along the edge. In the holes put your brushes. Then get/find/make a (copper?) ring that sits on the outside perimeter of the disk, and mount it to the threaded hole with a bolt that connect to the welder ground. This ring could be bent round from a narrow strip.

This may make it easy to have multiple brushes to share the current (though their size is limited by the plate thickness), and they would be (at least partially) protected from spatter and grinding grit.

Other thoughts:
-you may need to experiment to find the best materials.....could you use just steel ball bearings as brushes?
-could the brush be a small spring and a tight "slip fit" copper rod, with a rounded outer end.
-I think I saw some bb-gun BB's with a copper coating, but I can't say how thick.....

Is there room inside the housing for the brushes? They could run on the back of the output plate.

-brino

 

[RJSakowski]

Actually, I would look at insulating the dividing head from the work if at all possible. Passing electric current through bearings is never a good idea. When the currents can reach several hundred amps, even worse. If it is not possible to isolate the work from the drive, at least bring the electrical connection in downstream from and rotating surfaces.

The Delco Remy brushes are capable of passing several hundred amps. Since this is not a high rpm application, you could beef up the brush pressure for more positive contact.

 

[woodchucker]

Actually, I would look at insulating the dividing head from the work if at all possible. Passing electric current through bearings is never a good idea. When the currents can reach several hundred amps, even worse. If it is not possible to isolate the work from the drive, at least bring the electrical connection in downstream from and rotating surfaces.

The Delco Remy brushes are capable of passing several hundred amps. Since this is not a high rpm application, you could beef up the brush pressure for more positive contact.

If the ground is on the faceplate, and the arc is on the piece, the shortest path never touches the bearings. So there shouldn't be a problem right?
I like the idea of using a braided copper wire as the brush, just cinch it up on the outer perimeter of the face plate.
It does seem a shame to ruin a good divider, but it is yours. I probably would have done it differently, and probably less expensively.

 

[Ironken]

Interesting idea, but I wondered if you'd end up with a big mass of sintered graphite inside........

What about turning this inside-out.......once you machine off the degree scale, drill a number of radial holes along the edge. In the holes put your brushes. Then get/find/make a (copper?) ring that sits on the outside perimeter of the disk, and mount it to the threaded hole with a bolt that connect to the welder ground. This ring could be bent round from a narrow strip.

This may make it easy to have multiple brushes to share the current (though their size is limited by the plate thickness), and they would be (at least partially) protected from spatter and grinding grit.

Other thoughts:
-you may need to experiment to find the best materials.....could you use just steel ball bearings as brushes?
-could the brush be a small spring and a tight "slip fit" copper rod, with a rounded outer end.
-I think I saw some bb-gun BB's with a copper coating, but I can't say how thick.....

Is there room inside the housing for the brushes? They could run on the back of the output plate.

-brino

Brino, thanks for taking time to put all of your ideas out there. The spring loaded copper rod riding on the degree plate is the one I like best.

 

[Ironken]

Actually, I would look at insulating the dividing head from the work if at all possible. Passing electric current through bearings is never a good idea. When the currents can reach several hundred amps, even worse. If it is not possible to isolate the work from the drive, at least bring the electrical connection in downstream from and rotating surfaces.

The Delco Remy brushes are capable of passing several hundred amps. Since this is not a high rpm application, you could beef up the brush pressure for more positive contact.

I'm looking into the starter brushes as well. Their current carrying capacity is high! Thank you.

 

[Ironken]

If the ground is on the faceplate, and the arc is on the piece, the shortest path never touches the bearings. So there shouldn't be a problem right?
I like the idea of using a braided copper wire as the brush, just cinch it up on the outer perimeter of the face plate.
It does seem a shame to ruin a good divider, but it is yours. I probably would have done it differently, and probably less expensively.

I thought about the braided copper wire but, I couldn't come up with an effecient way for it to follow the head when I pivot it horiz to vert......unless I turn a wider ring and wrap a spring loaded braided cable around it and a bracket to the body. Good idea Wood!

I only have $160 in this delivered. Could I build one as compact and clean for $160 that pivots horiz and vert with my time included? Probably not. I have side work lined up that pays way better than my own projects do.

To ease everybody's troubled mind on the torture of a good dividing head.....had I purchased a complete unit, it would have found a home on my mill. What kinda animal do you think I am? Holy crap at the negativity about this project. You woulda thought I was clubbing baby seals.....I stopped doing that years ago.

 

[Wreck™Wreck]

If you ground to the housing the current will pass through the bearings, build a brush holder with spring loaded carbon or copper brushes that ride on the back plate.

I have built multi conductor slip rings in the past using stock brushes from McMaster, actually copper brushes would work fine in such a low speed application.

Good Luck

 

[woodchucker]

To ease everybody's troubled mind on the torture of a good dividing head.....had I purchased a complete unit, it would have found a home on my mill. What kinda animal do you think I am? Holy crap at the negativity about this project. You woulda thought I was clubbing baby seals.....I stopped doing that years ago.