Burn up Gearmotor?

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I want to use a small 110v gearmotor to turn a shaft while I weld on the shaft. Will the arc damage the gearmotor? Do I need to electrically isolate the gearmotor from the shaft?  If so, what do you suggest - a non-conductive coupler? Thanks for any replies.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:How do you plan to attach the welder ground to the shaft while it's turning? Just make sure the ground stays continuous to the shaft. If it happened to stray thru the gearmotor, it would certainly wreak havoc w/ the bearings in it, I don't know about the motor.                         HTH,                                MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Hello! wb4rt  You could use a Rubber Shaft Coupling at the motor then between the rubber coupling & your shaft build a Bracket to hold a steel bearingor something like a U-jointto the shaft, that way you'll have a place to put the ground and the rubber coupling will protect your motor!  Hope you understood that if not just let me know and I'll draw something up!  Mike E.     "Tell Me,I'll Forget" "Show Me,I'll Remember" "Involve Me,I'll Understand"
Reply:Originally Posted by tenacrewoodsHello! wb4rt  You could use a Rubber Shaft Coupling at the motor then between the rubber coupling & your shaft build a Bracket to hold a steel bearingor something like a U-jointto the shaft, that way you'll have a place to put the ground and the rubber coupling will protect your motor!  Hope you understood that if not just let me know and I'll draw something up!
Reply:Hello! mla2ofus This drawing is what I was thinking of,Can't see why it wouldn't work but I my be totally wrong in my thinking?  By tenacrewoodswb4rt - Hope this helps, if my thinking not too far gone.. Sorry about the bad drawing my L-bracket is not in the proper place & a bearing  of some type should used so inter part but the outside doesn't!! Wher I said I saw this on an Ieternet site & It worked, That's what was said but I wasn't there so I'm can't verify this as true!!! I may be totally Crazy - Just a Thought!!Last edited by tenacrewoods; 11-14-2009 at 10:24 PM.Mike E.     "Tell Me,I'll Forget" "Show Me,I'll Remember" "Involve Me,I'll Understand"
Reply:Isolate the motor from the metal frame it sits on by putting a rubber pad under.  Make sure bolts are not a conductive path.  Use a standard coupling as you plan to isolate the shaft.  Modern welding machines are properly isolated and the welding "ground" and the electrical panel ground are separate. You should not have any problems if everything is working out right however I have lost count of the number of times I have seen weld current damage.  Make sure your welding ground connection, properly called a "workpiece connection" is riding on the shaft that you are welding on to prevent current going through bearings.    A brass or copper shoe riding on the shaft works well.  In one case I saw two shoes used so that if one momentarily did not carry the current the other was still touching.... belt and suspenders.  There are commercial ground clamps/workpiece connections with a swivel included.
Reply:How fast do plan to turn the work piece? Turning the work too fast or slow will be the same as moving your hand too fast or slow.
Reply:Belt drive it and you're done.  Gives you more gearing too.My name's not Jim....
Reply:Hey Guys! Thanks for all the tips and input. Great drawing there, TenAcreWoods! I need to learn how to do that.It seems like I need to isolate the gearmotor for sure, not worth burning up an $80 item.I thought I would mount the gearmotor to a piece of plywood, put a rubber mat (right, Lotechman?) between the plywood and my welding table for extra isolation. Then I could clamp the plywood to the welding table to hold it in place. Then I will need to use a rubber coupling or a belt drive as Boost pointed out.Transit- I ordered a 10rpm, enclosed gearmoter. It has 8 lbs torque. I think that will be adequate for what I'm trying.The small shaft will turn on some in-line skate wheels with a ground from the table to complete the arc circuit.I'll post some pictures later in the week when I receive the gearmotor and get it all assembled. It's got to be a smoother weld than I get trying to turn it by hand, too much start and stop results in too much grinding.Again, thanks for the input and I will still be reading for additional input and ideas.This is why I like this forum - lots of great people solving problems and helping other people.Last edited by wb4rt; 11-15-2009 at 09:13 PM.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com
Reply:Here are pics of a weld fixture I made about 15 years ago for welding centers in rims. The gearmotor is 90 VDC 6 RPM with controller. The motor and controller are completely isolated.After trial runs a spatter sheild and twin rotary grounds were added. With their high output production water cooled mig welders they can do a 360 degree weld on a wheel center in about 30 seconds, vertical up. Attached Images
Reply:Hey Triptester!Thanks for the picture. That is a sweet setup for sure. I spoke with the chief engineer at the company that makes the gearmotor and he says it is not necessary to isolate the motor from the shaft I am welding on, but I already found a coupler with a rubber cushion, so I plan to use it. I will posts pictures when I get it set up.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com