Experiences With Inexpensive Indian Rotary Tables? (not for machining use)

[Ironken]

My family has built several welding positioners over the years. Some of them had hollow spindles in them for shoving drill pipe, drill collars thru to do hard metal on them as well as stub welding tool joints and such. The spindle would run on either cam roller bearings or mounted on pillow blocks. The spindle itself would get a band of either copper or brass buildup applied and turned down to a smooth finish running true with the spindle. Next, we would bend a strip of copper bar around the spindle and held in place with insulated fasteners. Usually micarta washers and bolts to insulate the copper bar from the frame. You would attach the ground cable to this copper bar. Doing this would keep most of the current from passing thru the bearings and gearing and direct the current to the weld area. Oh, forgot to mention, a sprocket was mounted to the OD of the spindle usually on the tail end of the spindle. Used a chain drive to a gear reduction DC operated gearmotor. Ken

Thanks Ken, I think that the chain drive to a gear reduction motor is the rout I'm headed. The little motor I have only has a #25 chain sprocket....I'm looking to build a smaller positioner.......something that I can tote around and store.

 

[rock_breaker]

Where I worked, building up a rock crusher bar the grounding clamp had habitually been placed on the out side of the housing thus the current went through the 7 inch double spherical roller bearings. On one occasion the current created an arc on one of the bearing rollers (about 1-1/2" diameter) it could be heard very well at start up. Replaced the $1200 at that time bearing and explained to plant management why they did not get raw materials for 8 hours. From that time on the ground was clamped to a bar temporarily welded on the roll. Some lessons come the hard way.

 

[Ironken]

Where I worked, building up a rock crusher bar the grounding clamp had habitually been placed on the out side of the housing thus the current went through the 7 inch double spherical roller bearings. On one occasion the current created an arc on one of the bearing rollers (about 1-1/2" diameter) it could be heard very well at start up. Replaced the $1200 at that time bearing and explained to plant management why they did not get raw materials for 8 hours. From that time on the ground was clamped to a bar temporarily welded on the roll. Some lessons come the hard way.

That's an expensive lesson! That's why I am gonna build some sort of brush set up.

 

[4GSR]

Dad built a rotary ground clamp that used mercury as a current carrying conductor for a customer of his. When the welders found out it contained mercury, a complaint was filed with HSE department. That was the end of that. They had to remove and dispose of the device thru a outside disposal company.