In article ,
Tim S wrote:
Thanks to you and John. My holesaws are bi-metal and in addition to
Dave's suggestion of water as a coolant, the bloke in Screwfix who's
keen on kit cars (much fibre glass) recommended applying tape over the
surface too to avoid chipping.

Again if you use a slow speed and don't push too hard grp shouldn't chip.
But as was said whatever you're fitting to it will have a flange to cover
the hole edge.

On the step drill front - I've never used on but it also sounds
interesting - I'll have a look into this.

Their main use is in sheet metal - they make a better hole than a normal
twist drill. I got a set at my local Sunday market for far less than most
charge - and wasn't expecting much of them. But they turned out to be very
good indeed.

--
*A cubicle is just a padded cell without a door.

Dave Plowman London SW
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