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

I had been thinking I had ALREADY added this [subject] photo to the
group, but, well, guess it's Alzheimer's! This quill has a 400 Hz.
12,000 RPM AC motor in it. Some machining to replace 1/4" shaft
on "bottom end" of motor with 1/8" collet/nut! And ABEC-7 bearings.
That "quill motor" is powered by simple "push-pull" 400 Hz
multivibrator and 95 VA transformer purpose-wound for the
application. I had used the old PET you see for years, but the last
of several I had on hand finally gave-in to alpha-particles, so I'm
slowly getting around to converting the 8-bit interface (yep, just a
9-wire cable to puter!) to work through a PC parallel printer-port.

The little blue motor atop the quill is a Slo-Syn 72 RPM SS-25 that
rolls a tiny cam-follower roller around a 1/4" pitch helix. So the
quill-travel is abotu 0.24". The quill can "do a hole" or "go down
and stay until told to return to "home". This latter way, the
machine can engrave.

The screws are 1/2" lead (1/8" pitch/4-start) stub-ACME. Thomson
linear ball-bearings/ways. Baltic birch base. Formica-covered top.

Can do about 3000 holes per hour, drill-rate. (one bit-size! Takes
time to change bits!) Jan Rowland