Tape Drive Capstans

[Chuck Guzis]

On 01/29/2015 10:55 AM, Ali wrote:
> Does anyone know if at any time in the past thirty years if the material
> used to make capstans has changed? I.E. can one be more confident of tape
> drives manufactured after some era to have non-goo capstan or is it that all
> tape drives (including ones manufactured now are ticking time bombs?
>
> Also how do you guys check capstans? Just stick long Q-tip in there? Thanks.

Capstans fail in several ways, in my experience.  One way is the "turn 
to goo", which seems to happen more on 80s-90s-era units.  Another way
is to simply dry out and crumble (no goo); I see that on 60s-70s units. 
  A third way is to permanently deform; e.g.,  when used as a pinch 
roller, forming a depression where contacting the driving shaft.

Oddly, I've never seen a case where a capstan hardens to a rock-like 
mass, as is encountered in typewriter or printer platens.  There, methyl 
salicylate can work wonders.

--Chuck