bad keys on terminals

O. Sharp ohh at
Fri Sep 15 17:26:43 CDT 2006

Quoth Tony Duell:

> Incidentally, do you have any experience of the 2-pack 'synthetic 
> rubbers' that Devcon (and others) make? I may well need to use such a 
> product to make a roller (for a classic computer -- an HP9820's internal 
> printer), and I do need to mix small amounts. The smallest Devxon pack I 
> can get over here is something like 500g, and costs \pounds 30.00. I am 
> going to go broke very quickly if I have to pay that out for every test 
> run (I know it won''t work first time).

I've worked with silicone RTV rubber. For molding/casting it has 
excellent properties for holding small detail, releasing cleanly from 
pretty much ANY material that isn't itself, and lasting for multiple 
pours; it's also done a good job staying stable in the container for long 
periods (read: 4-6 months) even after opening (so it can be used a little 
at a time), and have never had a mold lose any stability at all once the 
RTV had cured.

Having said that, I've never tried it for applications like printer 
rollers, rubber capstans and such. Whether its hardness or other 
properties would be suitable for that, I can't say; but I do think it 
would be worth a try. If you do try it, let me know what happens.

My only advice: Whatever you cast it in, make sure that cast is completely 
free of oils, grease, sulfur-based modeling clay (though "Sculpey" is 
okay) or latex. It'll prevent the stuff from curing, leaving you with 
either A) something a bit too unstable to use or B) one hell of a mess.  

Presumably the people at Devcon will have some documentation for their 
stuff which can be downloaded (and if they don't, try; 
they do for their products).


More information about the cctech mailing list