That, and I couldn't do plated through holes (the chemistry
seemed excessive).? SInce I was doing 100 pin TQFP (0.5mm
spacing), depending on whether or not I got the toner transfer
exactly right (and I swear it was environmental factors)....? I
got good boards or bad ones.? I did boards in production lots, and
of course, with toner transfer, you do one at a time.? So I did a
board, cleaned it up (before etching), cleaned it up (after
etching), drilled the registration holes, epoxied it, then drilled
it and hoped that the holes matched.? (the upside down drill press
was needed....).? Once that was done, stitched the board top and
bottom together, then built it, and hoped that there were no
breaks in the tracks I hadn't found.?
Once I started producing boards that had a higher parts density
(and I did 10/10 boards), I just couldn't do it myself.? It was
time to get the boards made elsewhere.?
Harvey
On 11/8/2020 7:49 PM, Bertho wrote:
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That sounds very familiar!
Bertho
?
?
Thanks.? Linear rail platform, linear stepper, stopping
points are settable (in use).? Worked well until I started
making PC boards that were too complicated to produce here.
Harvey
?
On 11/8/2020 12:04 AM, Bertho wrote:
Nice setup!
?
?
?
We're talking variations on a theme.?
Mine seems to be more elaborate, but then again, I could
throw stuff at it.
/g/homebrewpcbs/album?id=86511
Harvey
?
On 11/7/2020 11:19 PM, Mike wrote:
"The
registration holes need to be exact, which is why I
made an upside down drill press, which is far more
accurate (no parallax)."
I
used a different technique to get the same benefit.
FRP boards in the thickness we use are somewhat
transparent, you can see the drill bit from the
other side right down to the point of contact, thus
no parallax, same as above. To use a normal, bench
mount drill press, I purchased a single-board camera
with NTSC output that I then fed into a small TV
set. I built a small holder for the camera (about 1
inch cubed) plus a 45 degree angle mirror so that
the debris from the drilling did not fall on the
camera and cover the lens. Looking up through the
hole in the center of the drill press table, I was
able to position the board with one hand and lower
the drill with the other. Gravity works in the same
direction as drill force, so it was easy to position
the board while it was resting on the table and
still provide firm support against the drilling. It
worked ell enough for a cheap, out-of-alignment
harbor freight drill press to make accurate holes.
My approach does require the extra purchase of a $40
or less mini board camera but eliminates the problem
of keeping the board from falling down when not
drilling or of keep the board in place against the
force of drilling.
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