Re: [CAD_CAM_EDM_DRO] Setting up end mills for CNC, and other things.

Hi All:
I've been following the tool length offset discussion with interest.
Here are my rules of procedure, for what they're worth:

1) I always set the top of the stock to be Z0 even if it would have been
more convenient to reference from elsewhere on the job.
All cuts are always in negative Z

2) Clearance heights (and reference planes mostly) are always programmed as
absolute Z positive moves.

3) I always set tool length offsets directly on the machine with the tools
that I am using in the spindle and the stock clamped in place.
I reference the tool tip directly to the top of the stock, or to a gage
block stack that has been built up to the height of the stock if the top of
the actual block is rough or not flat or too small to gage from.

4) I avoid presetters as much as I possibly can. I find it too easy to
transpose numbers, put in a positive instead of a negative in the TLO table
etc, etc, etc. I never use tip comp on canned cycles, so I always know
where the tip of the tool actually is. (Keeps divots in the vise and table
to a minimum)

5) I squeeze jobs in the vise as much as possible and I have low profile
gooseneck clamps so I reduce the risk of crashing into a clamp. I will often
draw in the clamps and fixtures when I draw up the part. That way when I
verify, I can see if my entry or exit paths, or rapids might crash into the
fixtures.

6) I run the part in simulation on the control that will drive the motors,
not just in the CAM program. It's amazing how many times even high end
programs will pop in an unexpected move (like a full circle where it should
have been a quarter circle - early versions of Featuremill generated
programs driving a Centurion 6 control were especially bad for this).

7) I set the control to block mode and turn down the rapid and feedrate for
the first moves of each tool. I drop in a G00 Z1.0 move and keep a 1" gage
block handy. After that move is completed, I can visually check very easily
if the cutter tip is about 1" above the job. If it is, I know I haven't
goobered the tool length offset for that tool, and I probably have the
program at the right Z level for what I want. I keep the rapid and feedrate
down until the tool actually starts to cut. Then I crank them up.

That's it, that's what I do to keep those expensive and embarrassing moments
to a minimum.
Cheers

Marcus