Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Mon, 14 Jun 2004 07:13:07 -0000, Dave Mucha <dave_mucha@y...> 
> wrote:
> 
> > --- In Homebrew_PCBs@yahoogroups.com, dg140@f... wrote:
> >> For larger holes in plexi, drilling a pilot or starter hole works
> > well;
> >> speeds at about 500-600 RPM,; and the plexiglass bit with its
> > appropriate
> >> flutes and sharpness.
> >>
> >
> > The key to drilling plastics is to drill with a flat bottom drill.
> > the normal taper drill will remove a lot of plastic and as it 
exits,
> > the area of contact suddenly gets much smaller and before you know
> > it, the flutes will grab and push thry, often cracking the part.
> >
> > a flat bottom drill, like an end-mill will not suffer the same 
exit
> > problems.
> >
> > Dave
> >
> 
> i see... thanks, that's goin to be helpful.
> 
> st


Another way to drill plexiglass is to use a second sheet as a backing 
plate.  and take a piece of wood to hold it down on your drill 
press.  The wood should hold the plexi down very close to the hole so 
the top sheet does not lift up when the standard drill goes thru.  
This way, the drill has full contact as it goes thru the top sheet 
and you get a great hole.

I wish I had link to the site that explained this in great detail.  
it was a link from a drill sharpening manufacture that had done 
research on the best ways to sharpen drills for sheet metal and 
plastics and such.

Dave