Nick Müller wrote:
John Martin wrote:

The wider the slit, the greater the collapse. So it will lock on a
shaft that is considerably undersize. Not every use of these collars
involves shafts ground to bearing fits.

But if you collapse it to far, it will be permanently bent. Also, you
can't collapse it more than the gap on the side with the screw is. :-)

I really don't think that the key slot was made with much thinking.
Just think about the manufacturing-process:
You have a thick-walled tube, cut to length, drill and tap for locking
screw, then slit the open end _and_ cut the groove in one pass.
As that thing looks, they had to broach the groove as a further step. Or
are such tubes (drawn, with key slot) readily available?


Nick

You're right, Nick - it's a key slot and has nothing to do with
expansion or contraction. I tried to fool you, but couldn't.

You're probably also right about broaching the slot. If I had to make
them, though, I think I'd just run the slitting cutter a little deeper
to cut the through slot and the shallow slot on the far side in one
pass. But there is undoubtedly a good reason for a separate broaching
operation.

I don't know what is readily available. I have seen long bushings for
holding boring bars that are similar but without any setscrews. Why
should it be available, though? The companies that make these make
them by the thousands, if not the millions. I'd guess they start with
solid bar stock. Maybe they slit it before they bore it and cut to
length.

John Martin


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