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using an old chuck for an indexing head

Kevin Q

Aluminum
Joined
Mar 26, 2006
Location
Wyoming
I have a chuck in decent shape that is an extra. The bore dia. is slightly over 4". I often make shafts which have a square drive machined on one end. I will be retiring in 4 months and will no longer have the long bed of my mill at work with which to mill the square. I will be called upon to make the shaft in my home shop when my replacement doesn't have time.

I would like to know if anyone may have or know of a design idea I can use to make the 3-jaw chuck (12" O.D.) into an indexing chuck which I can feed the excess shaft length through. This would allow the shorter mill table (48") to be used to mill these flats. I hardly do more than 4 or 6 flats, although the option of having 24 divisions may be handier in the long run. I do have a 15" Troyke table I could accurately lay out divisions with.

There will be need to be an ability to turn, locate and lock the chuck in the desired position. I would also need to make a dead center for the end of the shaft. I anticipate there could be some vibration problems with my face mill.

Thanks all, you've been a great help in the past. KQ
 
Mount the chuck to a backplate and shaft with sufficient through hole size. Make a pedestal to mount the shaft to with a bore close to shaft dia to act as a bearing. A plain bearing is probably better than a ball bearing, simpler and you won't be spinning it fast. I'd go steel on steel. You'll want a locking feature so either split the pedestal bore so it can be clamped or make a clamp like that used on a tailstock spindle. Use your rotary table to make a disk with the number of divisions you require, 24 sounds like a good number. The detents could either be holes in the periphery or v-notches for a pawl to drop into. The index collar could be built into the backplate. Make your tailstock to match the center height of the chuck. If you need the chuck to be dialed in to eliminate runout, you should be able to design the backplate to have external "set-tru" adjustment screws that act on the OD of the chuck to center the work piece. Hope that all makes sense. You many not be able to take 1/4" deep cuts but it should get the job done.
 
Since the chuck is 12 inches diameter, I wonder if a flywheel and ring gear would work as a backplate?

If there were a suitable number of teeth to get the divisons you would need.
 
I'd make an oversized collet indexer.

4" sch 40 pipe has an ID just a tick over 4" so there's a cheap spindle. Some flat plate or a disk off a solid round could be a backing plate. Use your mill to put a 36 hole pattern in it, 10 degree increments. Then use another plate for create a 1 degree vernier.

A toolroom masterpiece it is not, but it would be serviceable.
 








 
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