On Thu, 14 Mar 2013 02:32:50 GMT, Doug White
wrote:

"Paul K. Dickman" 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

You mount the rod into a collet and collet block like these
http://littlemachineshop.com/product...ProductID=3190

You use one edge of the block to locate your work piece
You cut a slot, rotate the block, 180 deg and cut the other slot.

I guess I wasn't clear enough. There is one slot on each end of the rod,
not two slots on one end. I have a collet block, which is fine for
cutting one end, but you have to remove the rod to cut the other end, and
then you have the problem of aligning the rod to the block so the slots
are at identical angles.

Doug White

Id use a shaper and a V block with a flat to ref to.

Particularly if the rod is longer than the lift of my mill.

Gunner

The methodology of the left has always been:

1. Lie
2. Repeat the lie as many times as possible
3. Have as many people repeat the lie as often as possible
4. Eventually, the uninformed believe the lie
5. The lie will then be made into some form oflaw
6. Then everyone must conform to the lie