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

ahhh....skate bearings....of course! <g>

Sorry 'bout that...I should've figured that one out
myself. Put it down to late-night fatigue.

Aren't ABEC-9 bearings an ultra-tight machine-tool
grade? What the heck are they doing in -rollerskates- ??

I'd think they'd be $50 to $100 bearings!

I guess if you're only drilling a few holes, limiting the
feedrate is OK. I have had to drill boards with 600+
holes; and have no desire to -slow- the machine! <grin>

I'm currently running my Techno table at 400ipm slew,
and around 400,000 steps/sec/sec accelerations, so the
drill-down time has now become the larger portion of
the overall job-time. And with 60krpm instead of 25-30k,
I could -double- my trace-cutting speed...which would be
really sweet!

Don't know about you guys, but whenever I'm waiting
for a board to finish isolation, I'm alway chomping at
the bit wanting it to be DONE, so I can build it and
see how it works! <g>

I can't spend $3000 for a spindle, but I've worn out
so many crappy Dremels over the past 15 yrs, that I've
easily burnt up $300-400 so far. I'd gladly spend, say,
$300, for a nice little 50-60krpm unit with decent runout
and not-outrageous noise. If one were available.

Buy one decent spindle, and be done with the problem
forever. But the market is probably too small for anyone
to make such a thing; especially if nobody is willing to
spend more than $39.

Air: I've always kept my compressor outside under a
little 'shelter', for lack of a better word. Also, I chose
a unit with a 60-gal tank...it hardly runs at all. So the
worry about compressor-noise hasn't been an issue for
me.

I would think that a purpose-built PCB spindle would
consume far less air than those cheap die-grinders.
I know that the 200krpm dental handpieces use hardly
any air at all. The airlines feeding them are only about
.100" ID !

Air-consumption is directly proportional to both precision
and power-output; and PCB drilling/isolation isn't a high HP
job. It would seem that 50-100W would be plenty. The
Dremel is...about 125W -input- power, if I recall right.
Of course, it's such an inefficient motor that it's -output-
power is probably only 75-100W, and that's at full load.

What it actually produces during drilling might only be
a fraction of that...25-50W of mechanical power maybe?
A well-made 50-100W air-motor spindle might be pretty
reasonable on consumption.

Die-grinders are noisy because they run open exhaust; right
there in your face. But if the exhaust is plumbed away,
and if the tool is made well, an air motor can be pretty quiet.
I once worked on some air-powered factory-automation
equipment that used plumbed exhaust; and was pleasantly
surprised at how easy it was to stand right next to it while
discussing it in normal tones.

Heck, it's not like these cheap electric tools are very quiet
themselves... <g>

Appreciate everyone's thoughts and viewpoints on this.
It's very interesting. The spindle is such a key portion
of the setup.
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