HP-85A tape drive conversion
hp-fix at xs4all.nl
Wed Apr 1 04:37:28 CDT 2015
> -----Oorspronkelijk bericht-----
> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Marc Verdiell
> Verzonden: woensdag 1 april 2015 7:36
> Aan: cctalk at classiccmp.org
> Onderwerp: RE: HP-85A tape drive conversion
> > So the roller on my -85A tape drive is marginally ok [.]. While the
> >second option would work, according to the video it "just barely makes
> >the capstan roller contact the bottom portion of the tape capstan
> >wheel". That concerns me, as if it's "barely making contact" I'm
> >concerned that over
> >this would wear the capstan roller motor shaft and perhaps wear down
> >the wheel, not to mention potential vibration.
> It doesn't wear the shaft, does not cause vibrations. But it eventually
> the edge of the rubber replacement you put over the capstan (shrink tube
> surgical tubing in my case). Eventually it fails and you have to put a new
> > So. two questions: What SHOULD the outer diameter of a good capstan
> > roller be on that drive
> Dunno. If you have a semi good capstan, can you measure it? Apparently
> critical, since I got the tapes working OK with a thin shrink tube coating
> as a thick surgical tube coating.
> >does anyone have other suggestions for how to make the capstan roller
> I can think of at least two solutions.
> Solution one is to glue a metal or plastic "puck" of the same diameter as
> bare roller on top of it before recoating it. It's simpler than machining
the cap I
> show in my video, but you still need to have someone machine a simple disk
> on a lathe. That should be pretty cheap.
> Solution two requires someone good at making rubber. It would be to cast a
> rubber cap of the right diameter and thickness, and with a pocket on the
> bottom so you can slip it or glue it over the existing bare capstan. So
> not need to machine anything, just slip it over the bare capstan. If
> about an outfit that can do this, or can explain to me how to cast rubber,
The last option wouldn't work because the top of the capstan would be to
flexible, which would prevent a constant drive of the tape roller.
I'm using a simpler method than I described in the original article, I'm
using a piece 10mm aluminum tube of the right length.
Then machine the capstan to the right size ~8 mm (a little over size) and
press the tube piece with some 2k glue over the capstan.
When the glue is dried enough I machine the capstan to the right size, and
glue the rubber to it.
It's a little easier to do then the methode described in the original
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