Advice for tape drive repair / maintenance
technobug at comcast.net
Tue Dec 19 02:29:30 CST 2006
Around Mon, 18 Dec 2006 23:21:23 +0000 (GMT),
> ard at p850ug1.demon.co.uk (Tony Duell) wrote:
>> The drive itself: the rubber roller driving the aforementioned
>> roller had melted. Clearly visible is the area where the rubber meets
> Baiscailly you have to replace the roller. Replacements that have been
> successfully used (depending on the machine, etc) include silcone
> O-rings (possibly with a grobe machined in the original hub, or a
> new hub
> made), heatshrink sleeving, silicoe rubber tubing (fuel line for
> glow-plug engines, for example), etc.
> I've wondered if the 2-pack elastomer materials sold by e.g. Devcon
> work. Make up a mould and cast a new roller. A lot of work, but if it
> does the job well it'd be worth it in some cases.
I've had extremely good luck using Plasti Dip <http://
www.plastidip.com/industrial/plastidip.html> to repair capstans. The
product lays up in layers of 2-8 mils (depending on dilution) and
produces an extremely uniform coating. I have repaired several HP
tape decks out of 30 year old test equipment which required a layer
of 70 mils. The worst runout was less than 1/2 mil. The material
appear to be sufficiently durable for the task. The only drawback is
the requirement for patience - each layer requires 30 min. minimum
drying time. After a bit of experimentation I found that floating a
bit of solvent on the surface maintained the coating consistency from
dip to dip.
>> For those of us with machine tools, I wonder if a roller can be "fine
>> tuned" to the proper diameter by fitting an oversize piece of
>> neoprene tubing to the roller, cooling the whole affair in dry ice,
>> then machining it (on a lathe) to the proper size. I can't recall
> I believe it can, although cooling to liquid nitrogen temperatures is
> recomend (if only beacuase it takes longer to warm up again, so you
> longer to take a cut).
> I've also heard you _can_ machine 'rubbers' at room temperature,
> but that
> the tools are totally different from those used for metal turning.
> May be
> worth investigarting.
> I've not tried either though.
Cooling to LN2 temperatures has its drawbacks: the rubber either
separates from the mandrel or it shatters - or both... The rubber
becomes glass-like and you cannot use cutting tools to machine. A
number of years back back in grad school I attempted to repair a
roller for a Van de Graaff generator using LN2 and failed miserably.
An old machinist got his chuckles watching my many tries. He took a
CO2 fire extinquisher to cool the roller and used a grinder mounted
on the lathe to surface the beast. You have to warm the object up
every so often to find out what the dimensions really are.
I've since surfaced a laser printer's pickup roller using a Dremel
grinder mounted on my mini-lathe at room temperature with good
results (didn't help one bit in the printer - those rollers are not
just rough, but have a directional nap).
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