I am using my old US Machine Tool vertical mill. It's about a 1800# knee
mill. Plenty stiff when all locked down. I know I am on the high side
of the speed range at 350 rpms min. speed. Someday, a VFD is on my list
if I can ever figger out how to spec one out. I still have the original
3 phase motor which I replaced with single phase when I got it.
Yes, I learned that "edge hole" trick recently. It makes a
tremendous improvement in cutting rate and saw life. Much less pecking
needed, of course.
I use the dark brown sulphurous stuff. I buy it at the hardware
store as "pipe thread cutting oil".
I will look at the links you suggest.
And yes, I used to do it using the "several tool change" method, but
with the hole saw, I can do in 3 or 4 minutes what took me almost 20
minutes the "old" way. In "the old way", I had to go up to my largest
twist drill, 1 5/16" and then bore from there. I really learned how to
hold my breath for a long time using that HUGE (to me) bit at 350 rpm.
to go 1 1/2" deep!
As it is, tolerances are such that I have to try to come close, but
undersize with the hole saw, then to the boring bar for the last cut.
Normally, I am close enough that once I adjust the BB for the job, I can
leave it set there and just plug it in, bore, and go back to the hole
saw for the next one.
-----Interesting problem, though: Recently I bought some new hole saws,
I from each of 4 well known mfrs. 3 of the 4 had on tooth hanging out,
producing an OVERSIZE hole---- wasted one part!!.
The Starret brand turned out to be best by a long shot over the other
three. I chucked the "bad" ones up carefully in the lathe and ground
off the offending tooth or two with the tool post grinder.
In future, I will take a test cut on new hole saws in scrap, even
though the Starretts have all been right on. And, for what it's worth,
these 1 3/8" hole saws tend to cut 10 to 20 thou oversize.
Pete Stanaitis
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F. George McDuffee wrote:
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What are you using to drive the holesaws? One trick on hole saws
is to drill a hole or several holes just inside the finished
diameter so the swarf has somewhere to go. Easy to do on a mill,
less easy on a drill press. Also what coolant are you using?
For what looks like a better price on an annular cutter see
http://www.drillsandcutters.com/hssanho1dia224.html [60$]
http://www.ameritradeco.com/page/961257 [75$]
Also if this is not a high volume job how about a silver and
demming drill? You would have to change tools several times, but
this could be less cost. [c.28$]