5C collet indexer

[mklotz]

In another thread,

http://www.homemodelenginemachinist.com/index.php?topic=18084.msg187863#msg187863

one of our members, hmember, asked for more detail on the 5C collet divider I made.

Not wishing to hijack the thread, I started this one to pass on some more photos of the device.


Shown below are the two main components of the device. On the right is the collet chuck which is shaped exactly as one would shape a 5C chuck internally. On the left is the clamp that holds the chuck. It is split and fitted with a SHCS to lock the chuck in place when required. (When the clamp is used in the mill vise the clamping action of the vise closes the clamp and the screw is not required.) The clamp is fitted with a small brass finger stop that allows it to be accurately re-positioned in the mill vise.

The chuck has a dead flat bottom so it will sit vertically in the mill vise. When this flat base is aligned with the clamp base, the 24 indexing holes are just above the top of the clamp and precision pins in the chuck can be used against a pin fixed in the clamp to effect the indexing action.

These pictures show the draw-nut used to tighten the collet and the spanner used to tighten the draw-nut. When the nut is fully tightened on the collet in use it's completely hidden up inside the recess turned in the base of the chuck. This is done so the chuck can sit flat when used vertically.

Since the draw-nut is hidden when tightened, a special spanner is needed to reach up into the recess to tighten/loosen the nut. The one shown will do that. It has holes for tommy bars to provide the torque to activate the nut.

This strange cylindrical spanner shape accommodates the situation where the collet is used horizontally on a long piece of stock that projects out of the back of the collet. The spanner is slipped over the projecting stock, its "teeth" engage the slots in the nut, and the tommy bars activate the nut.

 

[hmember]

That's right up to your usual clever standards, Marv. That's a must-make.

I see an orifice (either a through hole or maybe for a set screw?) just above the ring of 24 holes in the collet chuck. Is that used when tightening the collet i.e., is that used with the collet's keyway? or maybe it's for something else . . .

Theoretically, you could put several 'rings' of holes above the 24-hole ring, with different numbers of equally-spaced holes. Sort of the same principle as a dividing head, if you know what I mean.

Thanks again!

 

[steamer]

Nice one Marv! Been thinking about a simple indexer for my SB lathe spindle....I think 24 is the magic number for one as most simple division is carried out for 2, 3, 4, 6 and 8. I have seen indexers set up for 60, but I don't think thats any better. Up over 12, I usually use a dividing head anyway. The 5C chuck in my Logan is set up for 24 position indexing and works great!

Dave

 

[cfellows]

Nice indexer, Marv! I'm guessing the small hole above the ring of indexing holes is a setscrew that engages the slot in the collet to keep it from turning?

Chuck

 

[mklotz]

Yes, the small hole contains a brass dog-point screw that engages the slot in the collet to keep it from rotating.

Additional circles of holes are certainly possible. Fifty or a hundred would be nice for calibrating dials but that many holes might mean impossibly tight hole spacing.

I suppose another possibility would be to make some ring gears with an ID that matches the collet OD. Slip these over, secure, and arrange some sort of detent instead of my crude pin-against-pin stop.

Many refinements are possible. That's where the fun comes in.

 

[Blogwitch]

If I didn't already have all my indexing sorted Marv, I would surely be following your lead.

You have a very nice cleanly designed setup there.


John