Re: [CAD_CAM_EDM_DRO] drilling techniques for plastic to get specific sized hole?

Lloyd Leung wrote:

> I have either, UMHW, Polyethylene, or something like cutting boards.
>
> I'd like to know the technique for drilling plastic.
>
> I want a 1/2" hole... however, when I slide it over my 1/2" precision
> ground rod, the hole is too small...

I don't think you can drill precision fit holes in soft materials. the
material deflects away from the cutting edge, and then springs
back, making the hole small.

I would bore it on a lathe (if available, otherwise use a boring head
on a drill press or mill). Open it up in tiny increments until you get
the fit you want. Another way would be to drill it as close as you can,
and then sand the hole ID until it fits right. Spinning the part on the
lathe and applying sandpaper with a stick to the ID will generally
keep the hole pretty round while opening it up.

Jon