Bob La Londe wrote:

Ok... my little toy mill is never going to scream like some of those
machines featured in YouTube videos, but I was able to do some much faster
than normal cutting in the last couple days. A lot of times I have to leave
the machine running when making an aluminum part while I go off and do other
things. I've found mostly I can take off .001 to .003 per pass dry cutting
with the smaller cutters at a moderate speed. .125 cutters and bigger I can
be a little bit more aggressive, but I can bog down my stepper motors. I
made a fishing bait injection mold this last week in my spare time, and
since it was just a cavity as soon as the cavity got some depth I filled it
up with WD40 and left it to run. Never a single gum up or crash in 8-10
hours of machining. Not great for some of you guys, but awesome for me.

While doing a simulation run on one pocket to see how long it would take to
run I accidently started a script halfway through. Instead of crashing it
just cut. Did a pretty good job, and since it was not trashing the piece I
just let it run from there. I could only credit the WD40 I was spraying on
the aluminum. Nothing else was different.

I finished both plates of my mold and proceeded to cut sprue vents. It's a
detailed piece so rather than cut a bunch of individual sprues I cut a long
ball milled groove the length of the mold and then cut smaller vents over to
the main vent from each major detail. Anyway, for some reason I thought I
could cut the main vent in one pass... or I got in a hurry and didn't think.
.125 diameter ball mill .0625 deep in one pass. Ordinarily I would have
jammed the cutter almost immediately, but I got nearly an inch before it
stuck and the stepper would not push it. Oops. The first part of the cut
looked as good as a finish pass. Hmmm...

I was using the jog mode to make this cut.

I decided to play. This mold is a prototype anyway. I backed up the cutter
and looked at the whole work piece and realized that the entire piece was
coated in WD-40. I started my cut again and ran it at 20 IPM and just kept
hitting it with a burst of WD every half inch. It made a very nice looking
finish quality (appearance) cut in one pass. WOW! I moved the table and
proceeded to cut my main vent on the other side. Same thing except I played
with it a little bit and held off the WD some just to see. Consistently if
I stopped spraying it would stop at about one inch of travel. If I kept
tapping my spray trigger it just zipped through the work piece. Ordinarily
for something like that I would have written a code snippet to take off
about .003 per pass and then left it to run.

I really need to get back to work on my coolant rig.

For those who deride WD as a coolant / lubricant. It does wonders on
Aluminum. I know and have seen that I get faster results with the WD, but
some of my projects have cut times so long I can't stand there and spray
regardless. I just had never realized HOW MUCH difference it makes. I am
talking an order of magnitude difference. We aren't talking a 20-50%
improvement in efficiency, but in this particular experiment nearly 2000%.

I mostly cut dry on my Bridgeport. I find Kroil works well for tapping
in aluminum, for tapping in steel I use regular cutting oil.