centre drills

johnakay · Nov 24, 2010

my friend did a job for me and broke 2 centre drills.
he has not ask for a replacement but I would like to.
the hole is approx 3mm.
what size do I need, looked on ebay and it a little confusing well to me any way.BS4 ? BS2
is 4 ---4mm?

oilcooled :) · Nov 24, 2010

size doesnt really matter, there all generally small

http://cgi.ebay.ie/Pack-10-HSS-cent...Home_Garden_PowerTools_SM&hash=item3362bd8e79

these are them only 8 quid

sometimes called spot drills

Welderpaul · Nov 24, 2010

This gives a bit of a guide.

BS4 is the one you want to drill a 3mm hole.

johnakay · Nov 25, 2010

thanks guys. thats sorted!

jugs · Nov 25, 2010

oilcooled :) said:
size doesnt really matter, there all generally small

http://cgi.ebay.ie/Pack-10-HSS-cent...Home_Garden_PowerTools_SM&hash=item3362bd8e79

these are them only 8 quid

sometimes called spot drills

Wrongly

Spotting drill. Used for starting/centering holes, accurate, robust & dont break

Center drill (Slocome pattern) Designed for enlarging a (previously spotted) hole, for a lathe center to run in.
If used for anything else it's prone to wander, the stepped pilot is weak & breaks easily.