Carl Denk wrote:

> And on Walter's suggestion of Forstener bits, will have to try that,
> wouldn't have expected that to work. :)
>
>

The trick with any cutting of plastic is to keep the bit cool. There have b=
een
suggestions to pre freeze. I have done that works but a better way is to us=
e
coolant to keep the plastic below its melting point as it being cut. Plasti=
c is
an insulator and doesn't conduct heat very well so the bit needs to be cool=
ed.
Alcohol is a good coolant because of its low boiling point. Water will work
quite well but needs more care. It the plastic starts to stick to the bit i=
t isn't
cool enough.

For plastic caps that I have drilled I have usually used a mill or drill pr=
ess
at relatively low speed.

w..


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