A definite yes to your question. In fact, when doing such an operation, it
is almost a 'given'. I personally prefer to
round off the corners of the drill slightly which will help prevent the
drill from drilling oversize and also improves finish.

Of course, it's good for only a few holes, and the drill requires
resharpening afterwards. Also want to have a good hold
on the work.


"Robin S." wrote in message
news

"Harold and Susan Vordos" wrote in message
...

When hole size is critical, or you just plain want things to work out as
if
you're a skilled craftsman, start your hole with a center drill, drill
undersized, then open the hole to the desired size.

Harold,

Do you find you have issues with drills being pulled into the work when
double drilling? Working in a tool shop, we have no need for holes within
a thou or two (either rough drilled or reamed only) so I don't have to do
it very often at all. When I do, I find the drill frequently pulls into
the hole making for a broken drill bit, spun part, or both. We have gear
feeds on our radials at work so it's not necessarily an issue for us, but
HSM's rarely have that luxury.

Regards,

Robin