Replacement "pick" roller for card reader

[Ethan Dicks]

On Fri, Jun 27, 2008 at 07:12:52AM -0400, Brad Parker wrote:
> 
> I talked to several chemical engineers about "gooey" roller and they
> both said that once the polymer chains relax, there is no going back.
> As I recall, they mentioned ozone and sun light being bad.

That is my experience with "rubber" parts (ASR33 hammers, HPLJ paper
pickers, TU58 rollers...)  Once they go bad, you are boned.

> I've had good luck fixing tape drives with "rubber" hose used for food
> processing equipment. I don't think I used Neoprene - I think it was
> "Tygone". There are lots of varieties.

As others here have, I have used Tygon tubing of the right size to
refurb TU58 rollers.  For HPLJ printers and ASR33 hammers, I've been
able to find relatively inexpensive OEM replacements, so far...

> The trick was getting a small amount.  I had to buy 10'.  But I was able
> to find one with an I.D. which matched the shaft and O.D. which matched
> the original.  If you can, measure the original with a micrometer.

Again for TU58s, since they have shaft encoders on the motors, you
don't have to have *exact* replacments, but as it happens, the standard
hardware tygon tubing happens to work to replace the rollers.  Paper
pickers for HP LaserJets are almost 1" in diameter, so I haven't
tried to sub for them, except with "genuine" replacement parts.

As I've heard, if you have some refurb material that is barely too
large, one way to reduce things is to freeze the roller material
with Dry Ice or Liquid Nitrogen and turn the frozen rubber on a
lathe, but I haven't tried that personally.

The older our gear gets, the more important it will be for folks
to be able to replace soft bits on their own - eventually, even the
vendor spares will turn to goo and the only alternative to making
parts from scratch is staring at non-functional museum pieces.

-ethan

-- 
Ethan Dicks, A-333-S     Current South Pole Weather at 27-Jun-2008 at 13:20 Z
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Ethan.Dicks at usap.gov            http://penguincentral.com/penguincentral.html