27 Oct
2015
27 Oct
'15
10:07 a.m.
On Oct 27, 2015, at 12:33 PM, Jon Elson <elson at
pico-systems.com> wrote:
On 10/26/2015 11:38 PM, Chuck Guzis wrote:
I would think a counterbore would work better, because it doesn't cut on the sides,
only on the bottom.
paul
On 10/26/2015 08:54 PM, wulfman wrote:
The
ultimate way to drill holes in Plexi is with an end mill. It can make a slight chipping
when it punches through the back, so you either need a backstop material or lighten up the
feed a bit just before it goes through. (This of course requires a center-cutting end
mill, I prefer 4-flute for this.) 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