1520 plotter (was RE: Your VIC-20 is worth $300!!! W@W!) - test-drb@ccmp.vtda.org

31 Jan 2002

A good model railroad hobby shop (or a major suppliers like
www.walthers.com) will have mould making and resin casting kits. Some of the
current casting resins should be strong enough to use as a gear. You can
make an open mould, pour the resin, then put a glass plate over the open
side to smooth the casting, or just sand it smooth when it has cured.

Another thing to try would be to make a mould from dental plaster or
Hydrocal (a harder-than normal plaster of paris, available at hobby shops),
then heat it and open cast with a low melting point metal. What I would do
here is make the mould double-deep, then file the resulting casting to the
correct thickness.

Bob

-----Original Message-----
From: ard(a)p850ug1.demon.co.uk [mailto:ard@p850ug1.demon.co.uk]
Sent: Wednesday, January 30, 2002 4:07 PM
To: classiccmp(a)classiccmp.org
Subject: Re: 1520 plotter (was RE: Your VIC-20 is worth $300!!! W@W!)

<snip>

...
   There seem to
be several possibilites : 

 1) Make a mould and injection-mould them yourself. I think the David 
 Gingery injection moulding machine could easily do it, but the mould 
 would be very hard to make (cutting internal teeth on a mould that size)  
 Might not produce a clean casting, either. 
I bet the originals were moulded rather than machined.... Maybe then 
cleaned up by machining, though, but I doubt it, actually. The original 
gears are not that good quality.

<snip>