In article <is6rvl+afn3@eGroups.com>,
Dave <odd_kins@yahoo.com> wrote:
> Ron using the end mill as a counterbore is not the best idea anyway,
> unless you start with a drill the same size first. this will keep the
> endmill from chattering at the start of the cut. a piloted counterbore
> is best.
Sometimes "a man's gotta do what a man's gotta do".
I was doing a job recently which required a counterbored hole so I got out
my nice, new, M6 piloted counterbore, that I bought a few months ago
(first time I have tried to use it) and measured the pilot at 6.55mm. Now
that's a damm stupid size! I have 6.5mm and I often use 1/4" (6.3mm) as
an M6 clearance hole and going across to my usual supplier for a 6.6mm
drill wasn't convenient at that time, so I used the method you suggested
above, 10mm drill followed by a 10mm end mill. There still seemed to be a
a bit of chatter when the mill started but once it had settled into the
cut it was fine.
I still haven't been across and bought a 6.6mm drill yet and was wondering
whether to stick it in the lathe and turn the pilot down to suit a
standard 6.5mm hole. I guess it's HSS but Carbide should handle it -
shouldn't it?
--
Stuart Winsor
Midland RISC OS show - Sat July 9th 2011
http://mug.riscos.org/show11/MUGshow.html
http://groups.yahoo.com/group/gingery_machines/app/peoplemap/view/map
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