According to EdFielder :
"Rich Osman N1OZ" wrote in message
news:imJ7f.2956$I65.444@trnddc01...
I bought a cheap R8 collet for use in my neighbor's equally cheap
vertical mill. Surprise of the ages, it doesn't fit. I'm trying to
figure out whether the issue is collet or the mill. The problem seems
to be the groove depth. The tooling that came with the mill has a groove
that is 0.104" deep where as the collet has a groove 0.060" deep. The
collet groove is slightly wider, by less than half a thou.
What's correct? I Googled "R8 dimensions" (and standard, and drawing,
and every other combination I can think of) without luck. I'll RTFM if
I can find TFM.
The standard size for the groove should be 0.060- you will find that some
imported mills will have a key made for a deeper groove and in some cases a
wider groove as well.
Note that at least on a Bridgeport, the key is the end of a
dog-point Allen screw (which can be accessed through a hole in the back
of the quill). You'll probably have to rotate the spindle until the
screw lines up with the access hole.
There are actually *two* Allen screws in the hole. From what I
have read, it is often the case that the outer one (which serves to lock
the inner one with the dog point at a proper level) is one with the hex
hole all the way through. So -- you loosen the outer one, pass the
Allen key in to access and adjust the inner one, set the depth correctly
for that worst-case collet, then back the Allen key out so it is only
engaging the lock screw, and tighten that to hold the lock screw at the
proper depth. Then -- make sure that the one with the dog point has not
moved, so you can get that worst-case collet in and out without
problems.
I don't know that the mill which your neighbor owns has the same
system, but it may be worth checking for that, so you can adjust it (if
he so allows).
This is also good to know about so you can replace the dog point
screw if the key happens to get sheared off by a mishap at some time in
the future.
Good Luck,
DoN.
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