HP-85A tape drive conversion

Jay West jwest at classiccmp.org
Tue Mar 31 17:09:39 CDT 2015

Gene wrote...
I don't have any flexable filament, so that's not gonna work. :)
Gene, that may not be a problem. The existing roller is rubber around a
metal shaft. The shaft is thicker at the top under the roller. So I suspect
that if the existing rubber was removed, you printed a round solid cylinder
that was the same diameter and could be glued on top of the existing thicker
portion of the shaft, and then rubber or surgical tubing was put around both
solid pieces together... that may just do the magic.

FYI - in the how-to video that marc did, you can see the component as-is and
what must be done. That would probably give you a few ideas.

Also - rik, regarding the tape speed difference... the dc100 to dc2000
conversion that marc did (link above), he doesn't just increase the capstan
roller height, he also adds a resistor to the tape board. I haven't seen
schematics on the 85A drive yet, but perhaps this is to affect a slight
speed change?


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