26 Oct
2015
26 Oct
'15
11:59 p.m.
On 10/26/2015 08:54 PM, wulfman wrote:
Agree with Chuck, a moderate drilling speed is better, you do _not_ want
to melt your way through, you want to cut.
And my advice, sadly learnt and forgotten quite a few times, always after
drilling a critical part:
**** CLAMP THE JOB DOWN! ****
If you think you can hold the Perspex with your fingers, you can't and
your nice panel piece suddenly catches, climbs up the drill bit in a flash
and is wrecked before you can say something nice like 'Oh golly I do wish
I had clamped it down!' or words (not) to that effect.
For clamps I suggest those newfangled ratchet clamps. I bought some a few years
ago and they are the best thing ever. These things ar esuperior to the
average old-fashioned G-clamp in almost every way, except for when massive
pressure is required. (search 'crescent connect clamp' on eBay, the 12" ones
are excellent). And like G-clamps, you can never have enough of these, get
some different sizes.
Steve.
To effectively drill in plastics you need to run
the drill press on
the highest speed you can and use a freshly sharpened drill bit.
If this is Perspex/Plexiglas, I've had great results with a good sharp
Forstner bit in my drill press at medium (say 750 RPM) speed and a
not-too aggressive feed.. No melting, just lots of crumbly shavings.
I've done this with sizes down to about 1/4", but no smaller. When
you're almost through the material, turn it over and complete the hole
from the back side. Very clean edges, with no chips at all.
--Chuck