Homebrew PCBs

Dwayne Reid wrote:

> At 10:12 AM 4/11/02 -0700, Steve Greenfield wrote:
> >How 'bout this little thing? Too much weight to put in a plotter,
> >but maybe in a homebuilt router/engraver.
> >
> >http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43155
> >
> >58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile
> >from my house.
>
> That is probably the same as the unit I mentioned from Princess Auto.  I
> think that its cheaper here in Canada, though ($30.00 Canadian vs $36.00 US).
>
> >How are you guys measuring runout? Drill with a stiff bit then
> >measure the size of the hole? I don't have a micrometer that can
> >measure the inside of a round hole.
>
> I've done it that way (although that method includes any error resulting
> from an off-balance drill bit).  I also just stick a solid carbide shaft
> into the chuck and measure both play and run-out when rotating the shaft by
> hand.
>
> dwayne

If you can see the out of roundness with your eye or feel play with your finders
then its a pretty bad drill. I wouldn't trust it at all for carbide bits. The
small air powered die grinders look like a cheap solution, but are you prepared
to have a big thumping compressor to go with them ? These things suck a lot of
air for there size!

Alternatively you could use a professional electric die grinder, but these
usually are quite heavy and powerful for drilling boards. The grinder I used is a
BOSCH GGS 27 (see link below), runs at 27k RPM, has precision ground collet so
the round out is superb, compared to a Dremel at least. Normally a dial indicator
is used to measure out of roundness.

http://www.bosch.com.au/productcatalogue/spt3/grinders.htm