22 Aug
2007
22 Aug
'07
7:10 p.m.
Subject: Re: Gooey rollers again.
From: ard at p850ug1.demon.co.uk (Tony Duell)
Date: Wed, 22 Aug 2007 22:23:07 +0100 (BST)
To: cctalk at classiccmp.org
Actually is fairly easy once you know how. You need a lathe and a rotary
grinder with the right wheel (correct abrasive). Rather than using the
usual tool (cutting edge) you apply the grinder mounted on the cross peice
so than you abrade away the urethane, silicone rubber or whatever flexible
material is used. The process is slow but with care you get excellent
results. Learned than from a machinest that was really good.
The real trick is getting basic materials to make said rollers even if
they are the wrong length and shape but larger.
Allison
I picked up a nice Decision Data model 8010 keypunch machine through
govliquidation.
It looks to be in good shape EXCEPT some rollers have turned to goo.
They act just
like peanut butter, looks like it too. These are not simple round
rollers but are tapered,
and there are 16 of them in a complex arrangement. Any ideas on how to
fix them?
I guess I'm going to have to find some suitable plastic and turn them on
a lathe. Probably
beyond my ability.
Turning flixible materials is not easy, the darn stuff tends to distort
and not end up the size or shape you expect.
I've heard that cooling it to dry ice temperature helps. Liquid nitrogen
is too cold, the stuff then behaves like glass and just shatters.
Another posibility would be to make a mould and cast new parts using one
of the 2-part synthetic elastomers. The name 'Devcon' seems to ring a
bell for this, maybe a google search will find something. There's a book
entitled something like 'How to cast small metal and rubber parts' that
covers this, it's aimed at the classic car restoration gugs, but the
principles should be the same :-)
-tony