"azotic" wrote in
:


"Doug White" wrote in message
...
I have a project that requires a machining operation that I am
puzzling
over. This particular piece doesn't require great precision, but I
would like to learn and practice an accurate approach to doing this.

I have an aluminum rod, 5/8" in diameter, and 3" long. Each end will
be counterbored about 1/8" deep to a diameter of 3/8". I want to
mill a flat bottomed groove 1/4" wide from the bottom of the
counterbore to the outside on both ends, and (here's the tricky part)
I want those two grooves aligned with each other as accurately as
possible. Basically, there will be a flat keyhole shaped pocket in
each end of the rod, and I want the two keyholes to be vertical.

I can easily mill the groove in one end using a collet block with the
rod sticking up vertically. The rod is too short to just flip the
block upside down and mill the opposite end with everything aligned.
If I take the rod out of the block, I lose the alignment, and the rod
is also short enough that I can't really easily reach into the back
side of the collet block with an indicator to align the groove.
Because the groove is only 1/8" long, I'm not going to get much
accuracy that way anyway.

I could mill a reference flat on the rod, but that's an extra step,
and if I'm trying to learn here, kind of cheating. I can certainly
conceive of applications where that wouldn't be kosher.

While writing this up, it suddenly occured to me that I could
probably do both ends with the rod clamped in a Vee block. I should
have a Vee block that is short enough to hold the rod with good
access to both ends without removing the rod between operations.

Is that the only good way? Any other clever ideas? Any good excuse
to buy a new tool?

Thanks!

Doug White

How about using square or hex stock, then turn it round after you
make the groves.

Ah! That would also work. Unnecessary in this case, but a possibility.
The trick would be turning it into a smooth cylinder with both ends
already finished. Flipping it around in a collet would invariably leave
a small step, although in this case, that's not critical.

Thanks to everyone for theri input. I'll return the group now to its
usually political wrangling....

Doug White