Rotary welding table

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So, I am in the process of fabricating a rotary welding table.  Base table is a 22" lathe cast iron faceplate, that I have fabricated a heavy duty taper bearing and spindle to mount it to a base.  Here is my question.  Grounding the work piece is easy as the table will be grounded.  so, do I need to be concerned about running the ground current through the taper bearing the table rides on, or should a fabricate a grounding contact that will basically be a sliding copper "brush" that is spring loaded against the bottom of the face plate?  I am a little worried about actually using the bearing for transmitting the ground connection.thoughts?  Am i overthinking this...............Last edited by tom fleming; 09-11-2020 at 09:46 PM.
Reply:I would use at less two slip rings You find brushes on internet and slip just find brass or copper rings or just use brazing on steel ring  .Since a rotating table it 100% duty cycle.Dave  

Originally Posted by tom fleming

So, I am in the process of fabricating a rotary welding table.  Base table is a 22" lathe cast ironfaceplate, that I have fabricated a heavy duty taper bearing and spindle to mount it to a base.  Here is my question.  Grounding the work piece is easy as the table will be grounded.  so, do I need to be concerned about running the ground current through the taper bearing the table rides on, or should a fabricate a grounding contact that will basically be a sliding copper "brush" that is spring loaded against the bottom of the face plate?  I am a little worried about actually using the bearing for transmitting the ground connection.thoughts?  Am i overthinking this...............
Reply:You don't want the potential for the bearing to arc from the welding current. You can probably set up a rotary ground clamp for the table.https://www.esab.ca/ca/en/products/a...und-clamps.cfm
Reply:I have used slip rings or simply fan  out the cut end of a piece of welding cable and let it drag on a smooth portion of the bottom of the plate. There is a copper anti seize that has reported excellent results in cable reel bearings as well.
Reply:I finished building mine about a year ago. It was a two year long project(always something else comes up). I had meant to use a proper brush, and ring. Urgently needing some circular plates  cut , I decided to short cut the first one, and clamped the ground cable on the top plate a few times(until I nearly dragged the plasma cutter into the turntable). Then I decided on this solution. I have migged, tigged, sticked, and plasma cut on this a few times a month for the last year, and still dont have any pitting or discoloration of the shaft yet. Disclaimer, I haven't done much high amperage welding/cutting on this table(less than 200 amps). I also have a 3 jaw chuck, and a burn tabletop for this turntable.



No, I don't believe you're over thinking it. If you don't make a big enough path for the current, the bearings wont last long. Without a good ground on low amperage tig welds you might expect to get some current fluctuaction also. So far the HF hasn't been  a problem for the DC motor, and DC drive, but I've only done a small amount of AC tig on this unit. I would love to set this up with a stepper motor drive sometime in the future so I could get repeatable and reliable speeds.HTHLast edited by albrightree; 09-12-2020 at 01:29 PM.Reason: added hf concernAirco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:Abom79 did a really nice series of videos on building a rotary table like you're talking about.  Tons of details and a lot of really good ideas that I'm sure you'd benefit from -- including how he installed a ground.Personally, I was pretty sad to see the table get finished and then not really used in any of his subsequent videos.  Were it me, though, I'd have moved that beauty into the house right next to my reclining chair so I could relax in style!  


Reply:Looks greatSimple but looks like it will do the jobDave

Originally Posted by albrightree

I finished building mine about a year ago. It was a two year long project(always something else comes up). I had meant to use a proper brush, and ring. Urgently needing some circular plates  cut , I decided to short cut the first one, and clamped the ground cable on the top plate a few times(until I nearly dragged the plasma cutter into the turntable). Then I decided on this solution. I have migged, tigged, sticked, and plasma cut on this a few times a month for the last year, and still dont have any pitting or discoloration of the shaft yet. Disclaimer, I haven't done much high amperage welding/cutting on this table(less than 200 amps). I also have a 3 jaw chuck, and a burn tabletop for this turntable.



No, I don't believe you're over thinking it. If you don't make a big enough path for the current, the bearings wont last long. Without a good ground on low amperage tig welds you might expect to get some current fluctuaction also. So far the HF hasn't been  a problem for the DC motor, and DC drive, but I've only done a small amount of AC tig on this unit. I would love to set this up with a stepper motor drive sometime in the future so I could get repeatable and reliable speeds.HTH
Reply:My live welding reels on my truck have the current going through the trailer bearings they are made from and I have never had a problem. I built them around 30 years ago and copied an old weldor's reels that he had been using for longer than that with no problems.
Reply:

Originally Posted by smithdoor

Looks greatSimple but looks like it will do the jobDave
Reply:

Originally Posted by Bob

My live welding reels on my truck have the current going through the trailer bearings they are made from and I have never had a problem. I built them around 30 years ago and copied an old weldor's reels that he had been using for longer than that with no problems.
Reply:

Originally Posted by thegary

That will last for ever . That is what they do on steam turbines to ground the rotating assembly. Only they use a little heavier copper braiding .  They run 24/7/365 and the shaft shows no wear other than just seeing the rub mark.  In fact those are only held from one end and have a light spring that makes the copper stay in contact with the shaft.  Those assemblies weight 25+ tons and believe it or not there is a good amount of electric power passing through that rotor to ground on those turbines.
Reply:I was originally going to copy this one : https://weldingweb.com/vbb/showthrea...ing+positionerHe made his own brush holder, made from sheet metal and a chunk of brass. I also have a 250 amp capacity warner electric brush holder assy on my scrap pile from an old packaging machine.Thanks for the idea, but I probably wouldn't go with a roller on roller design as it puts all the contact in one point , and if any debris were to get on the wheels it could break continuity, or arc even with brass or bronze.  I often use the table for plasma cutting, which make a lot of debris. The system I've been using for about a year has never gotten hot  (even after welding 8 - 6" sch 40 pipe flanges) and never arced, or pitted the shaft. Have also done AC tig with HF at 180 amps, no problem. With aluminum the problem  was getting continuity from the work to the table top (I used a stripped piece of welding cable so I wouldnt get arcing craters from the ground on the aluminum). If I do get some time to work on it , putting some slots for hold downs will be next.Seeing those tappets just makes me think of the noise my 2005 hemi is making now. 235,000 miles and the ticking just gets more noticeable. Saw a youtube video , a guy showing how his tappets, and cam wore out on his hemi.   I haven't found it yet , but there was a TJS that had posted before the crash a rotary table too. I think thats where I got this idea from. His mounted into a 2" reciever on his bench, and used a scooter motor for rotation.Cant seem to find the thread through search though. Went to look a the Abom table , nice table , but he has at least 13   30min videos ..... wow . He does some really awesome machine work though. Wish I had the time to watch more of it.Old thread with aaron6061 in it  https://weldingweb.com/vbb/showthrea...ing+positionerolder one with the ground strap, and spring    -  https://weldingweb.com/vbb/showthrea...ing+positionerHTHAirco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60D
Reply:This is how I solved my grounding problem:



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Reply:My Ransome positioner using a brass plumbing fitting that touches the platen. See post #40, #41 and #54 of my re-build thread for photos:https://weldingweb.com/vbb/showthrea...91#post2232091