Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Stefan, thanks for the ref to Herb...

Chris, appreciate the detailed description of
your shop-made spindle.

Alan asked: "Is there an advantage to having speeds
exceeding 30000rpm? "

Yes, because a cutting tool can only take a certain
sized "chip load" per flute, on each revolution.

So, the faster you spin it, the faster you can drill;
or the less you need to run the tool close to its
strength-limit while maintaining a high feed-rate.

Obviously, everybody has different needs. For
someone who only drills 10 holes, twice a year;
a drill-press at 2,000 rpm is no doubt fine.

For someone drilling a 600 hole board once a week,
it's a mite more important to optimize the process
as much as budget allows.

The higher speed also comes into play when using
a CNC table to isolate traces; i.e. mill the traces
instead of etching them. Double the RPM equals
twice the linear cutting-rate. On a complex board,
this can mean cutting a 2 hour job to just 1 hour.

A big difference in number of noise-hours in the
shop, for sure! <grin>

Idaho asked: "I have a dc motor....with just a smooth shaft
coming out of the berring. How does one fit a collet to one
of these? "

Idaho, you would machine the end of shaft. You need to
bore a hole to fit the OD of the collets. Then you need to
cut a taper on the ID of the shaft-end, to fit the taper of
the collets that you chose. Then you need to turn the OD
to the right dia. for threading, and thread it for the cap/nut
which holds the collet in.

You may not have to make the nut itself; as you could
probably find a replacement-nut for some tool that already
uses those same collets.

Chris said: "I believe this thread started with making a drill
press of sorts for drilling PCBs..."

No, that was a previous thread Chris. I started this new one
a few days ago, specifically asking about spindles; and used
a new subject-line.

Adam, you spoke about a gap between the $150 die-grinders
and the $2,000 pro spindles. I think you're right. I'm going
to check into that. I have access to some mfg. capabilites
and design people. Perhaps I can come up with something...

If so, I'll certainly let everyone here know first.

Richard
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