Centre drills - size?

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

Reply to
Peter Fairbrother
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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

Reply to
Richard Edwards

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

Reply to
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.

Reply to
Austin Shackles

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