"Peter Fairbrother" wrote in message
...
Andrew Mawson wrote:


"David Littlewood" wrote in message
...
In article , Tom Miller
writes


I tend to use sheet metal drills for hole
starting. They are very short and are double
ended. you can break twice as many for the same
price!


Sheet metal drills?

David
--
David Littlewood

They are ground to a sort of a cusp - centre point and also cutting
edge at the periphery of the flutes

Are spot-weld removing drills the same?

Lots of them on ebay (spot, drill).


Black and Decker do the sort of drills Andrew is describing, under the
Piranha name. They work well in sheet metal (at least up to about 10mm) but
are expensive. Our workshop guys at work call them crown-point drills.
They are similar to the lip and spur drills used by woodworkers. Same basic
idea - cut the rim of the hole before removing all of the support.