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

I have SEVERAL tools that will help you machine PRECISION holes in plastic.
The first is a wood boring auger bit. You'd have to alter the center point
so it wouldn't try to screw into the plastic. (This would be my LAST
choice)
The second would be a Forstner wood boring bit. This tool bores the OD of
the hole and scrapes away the inner part.
The third would be a "regular" drill bit with the point ground to an angle
suitable for plastic.
Fourth would be an end mill.
Last would be a boring tool after predrilling a pilot hole to just under
final diameter. With this tool you CAN bore accurate holes in soft
materials. The secret is not to try machining the hole to rapidly.

I'd feed all of these tools thru the work slowly and use water to cool the
plastic so it won't melt around the edges while being machined.

If you make ANY hole the same size as the part that supposed to fit into the
hole, you won't get the part in the hole. You will need to allow about
.0002 oversize for the parts to fit. This can be accomplished by either
polishing the inside of the hole or the outside of the shaft/pin. The tool
I would use to polish the hole (made this in gunsmithing tool for polishing
chambers) is a 1/4" diameter steel rod with a 1" long slit sawn down the
middle
with a hack saw. Sandpaper is inserted in the slot and the tool is rotated
in a hand drill ot in the drill press. If you braze a cross piece on the
end you can hold it in your hand for use while the work is turned.

Smoke

> > I want a 1/2" hole... however, when I slide it over my 1/2" precision
> > ground rod, the hole is too small...
>