"Cross-Slide" wrote in message
...
On Sep 8, 2:58 pm, "Bob La Londe" wrote:
After the long thread on drilling and peck drilling I thought I'ld post
this
video for you as an alternative way to drill holes that seems to be
faster
than peck drilling for many of my applications. Yes, I'm doing this dry.
The darn day job keeps interfering with my hobbies and I still have not
finished my enclosure. It ramps in at about 5IPM and finishes the pass
at
20IPM. The cutter is turning about 15000 RPM.

http://www.youtube.com/watch?v=dM4LXXNzLYw

Yes, they are slightly out of round due to backlash and run out, but not
enough to matter for most applications. If I needed them perfectly round
I
think I'ld pocket them .005 to .010 undersize and then drill or ream as
needed.

Yeah, I'm sure there are a million reasons why this is a bad idea, but
for a
ton of applications it works great.

At 15,000 rpm and 5 IPM,

*** PLUNGE *** with a 1/5 horse motor. Taking .005 per pass.

you are annoying the metal out of the way,
not cutting it.
You want to cut the chips, not rub it to death. Maybe less rpm?
Or maybe clean the hole out under size at a faster feed rate, and then
a slower finish pass to clean up the hole to size. Speed might not
affect your backlash anyway. But the servo tuning might affect it's
ability to keep up to the feed rate.

Here is an example of a (small) full scale machine. A Robodrill. Just
for grins...
In aluminum, I was running 24,000 rpm,

And probably 2.5 horsepower. Makes a difference. Also so does 9000 rpm.

and pocketing at 180 ipm with a
3 flute Zirconium cutter 3/16" Diam .28" deep. Spiral plunge into the
bottom, and interpolate the hole. Holes from .500", .345" .280" .214"
30 holes in 28 seconds including tool changes and rapids all over the
part. Within a few 10ths over Thousand of parts.