I was looking for some new centre drills, and realised that I don't know how to size them - if I am single-drilling a hole of size X, what size of center drill should I use?
Thanks,
-- Peter Fairbrother
Centre drills - size?
Mar 05, 2009
3 Replies
ASFAIK if centering for drilling then produce a hole a little greater than the chisel point on your drill. Works for me
A better option these days IMHO is to use a spotting drill, leave the centre drills for their original purpose.
Richard
I completely agree with Richard on the use of spotting drills. I first saw them in the J&L "flier" and thought they sounded a good idea, and so they proved to be! I now only use centre drills for their ordinal purpose and for all other purpose use a spotting drill. Since they produce a conical sink without a parallel portion which guides the drill admirably. Even the great GHT admitted to breaking BS1 size centre drills! Regards Brian
On or around Thu, 05 Mar 2009 01:29:27 +0000, Peter Fairbrother enlightened us thusly:
d'you mean the little short tapered kind with a narrow nose?
I've gone off those, got some little short stub drills, which are handy for spotting.
anyway. I tend to go for one which makes a spot about the size of the intended drill.
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