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

[Ironken]

Ok, this table

http://www.ebay.com/itm/332138282892?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

is what I am looking at to frankenstein into a welding positioner. I was looking for knowledge or experience with one mainly regarding how smooth the crank rotates the table.

I am aware of what up to 300 amps will do to worm gears and bearings and I think I have came up with a way to mitigate that (by cutting down and lining the the table lock plates with copper and grounding through them....crude brushes).

I have a controller and DC gear reduction motor sitting here that wants to be put to use. The idea is to mount a #25 sprocket where the hand crank is on the table and drive that with a length of chain from the motor. The table is a 90:1 reduction ratio and the motor turns about 100rpms max. I am looking for a range of .5-2rpms. With 20 teeth on the motor and 10 on the table, I *think* I can get that.

Feel free to throw any ideas my way......Your ideas may be more skookumer than mine.

 

[woodchucker]

Why even use that table, you could do it 100 other ways.
How much weight do you need to handle?
Vertical and Horizontal?
What about a pillow block for shafting, and either plasma or on a lathe cut a table. mount it to the shaft using home made collar.
Drive it with either belt or chain using a variable speed DC setup, so you can dial in whatever speed you need. You can use an auto batter to power it with a charger keeping it charged, so you have plenty of amps.

That's what I'm thinking rather than work on a table and have to modify it, and not being real sure it will survive. You'll be in it for a lot less to begin with.
I would use copper wipers underneath the table that brush the table itself for good contact.

That's how I would build it. A window regulator at the junk yard or wiper motor is a good motor , or maybe a starter motor. Talk to a motor winding shop, they probably have something they would sell you that they want to get rid of that will do the job.

 

[bfd]

if the rotating part is well balanced it will be pretty smooth but if the load is unbalanced then it will fall on the heavy side bill

 

[woodchucker]

if the rotating part is well balanced it will be pretty smooth but if the load is unbalanced then it will fall on the heavy side bill

which are you responding to?

 

[Ironken]

Why even use that table, you could do it 100 other ways.
How much weight do you need to handle?
Vertical and Horizontal?
What about a pillow block for shafting, and either plasma or on a lathe cut a table. mount it to the shaft using home made collar.
Drive it with either belt or chain using a variable speed DC setup, so you can dial in whatever speed you need. You can use an auto batter to power it with a charger keeping it charged, so you have plenty of amps.

That's what I'm thinking rather than work on a table and have to modify it, and not being real sure it will survive. You'll be in it for a lot less to begin with.
I would use copper wipers underneath the table that brush the table itself for good contact.

That's how I would build it. A window regulator at the junk yard or wiper motor is a good motor , or maybe a starter motor. Talk to a motor winding shop, they probably have something they would sell you that they want to get rid of that will do the job.

I have the motor and drive in my hot hands. The table will only need to handle several pounds tops. I have a set of powered rolls for pipe up to 24" that I own but need to go pick up.

The rotary table is small and will flip horizontal or vertical, so that's the appeal. For stainless, the amperage is relatively low. Aluminum is where the amps get high.

I haven't ruled out building a full on positioner but I will be into it way more than a couple hundie.

 

[Ironken]

if the rotating part is well balanced it will be pretty smooth but if the load is unbalanced then it will fall on the heavy side bill

I think I get what you are driving at. Mostly small light parts here. The rotary table will be clamped to my heavy welding table and I can even use a tailstock if needed.

 

[bfd]

I was responding to how smooth it will turn the part. smooth until the weight shifts then the worm gear slop will cause part to jump bill

 

[f350ca]

I built one using a smallish gear reducer chain driven from a 110 volt DC gear head motor from a blue print machine. Made an adaptor for the output shaft to use 1 inch UNC chucks and faceplate for a wood lathe. Works great. Have it mounted to a 2 inch square tube that fits in a receiver welded to a post in the shop. Can stand it up for welding sprockets to hubs or lay it flat with long shafts supported at the other end with two casters welded to a plate.
For smaller parts you may need to have it run a little faster than you mentioned. Welding around a 1 inch shaft say to build it up you need to spin it fairly quick, maybe 30 rpm. Guessing there a bit I adjust the speed till the weld looks good.
I've cut 12 inch pipe on it with the plasma, then your down to 1 or 2 rpm.
Been running the ground through the reducer for years now with no ill effects, but may not have used that much current. Very rarely have the 250 amp mig cranked to the max.

Greg

 

[4GSR]

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

 

[Ironken]

I built one using a smallish gear reducer chain driven from a 110 volt DC gear head motor from a blue print machine. Made an adaptor for the output shaft to use 1 inch UNC chucks and faceplate for a wood lathe. Works great. Have it mounted to a 2 inch square tube that fits in a receiver welded to a post in the shop. Can stand it up for welding sprockets to hubs or lay it flat with long shafts supported at the other end with two casters welded to a plate.
For smaller parts you may need to have it run a little faster than you mentioned. Welding around a 1 inch shaft say to build it up you need to spin it fairly quick, maybe 30 rpm. Guessing there a bit I adjust the speed till the weld looks good.
I've cut 12 inch pipe on it with the plasma, then your down to 1 or 2 rpm.
Been running the ground through the reducer for years now with no ill effects, but may not have used that much current. Very rarely have the 250 amp mig cranked to the max.

Greg

I really like the receiver off of the bench idea.

Man, 30 rpms is screamin! I don't think I could keep up with that spraying metal core wire with my MIG.