HP-85A tape drive conversion

Rik Bos hp-fix at xs4all.nl
Tue Mar 31 16:03:55 CDT 2015

You shouldn't under estimate the force on the capstan.
I'm also not a fan of shrink tube, the it's to smooth and not durable. 
I've experimented a lot when figuring out how to make the QUICK40
modification (after I knew it was possible because Larry Afferton was
selling QUICK 40 HP-85's). 
I found the best way to refurbish the rollers was using small rubber sleeves
and grind them to the right size. The sleeves are glued to the capstan and
have much more friction than shrink tubes. Which results in less jitter and
a better and more constant tape transport. The exact measures of the capstan
can be found at hp9845.net : http://hp9845.net/9845/tutorials/tapedrives/


> -----Oorspronkelijk bericht-----
> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Smith, Wayne
> Verzonden: dinsdag 31 maart 2015 21:21
> Aan: cctalk at classiccmp.org
> Onderwerp: RE: HP-85A tape drive conversion
> > Date: Tue, 31 Mar 2015 06:20:04 -0500
> > From: "Jay West" <jwest at classiccmp.org>
> >
> > So. two questions: What SHOULD the outer diameter of a good capstan
> > roller be on that drive, and does anyone have other suggestions for
> > how to make the capstan roller "taller"?
> I would try gluing an extender piece on the end of the existing capstan
> perhaps using wood which is easy to shape.  Once you wrap it with a piece
> two of heat shrink tubing, I would think that it would all stay in place.

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