13 Dec
2003
13 Dec
'03
3:38 a.m.
On Sat, 13 Dec 2003, Mike Gemeny wrote:
I???m left to wonder of these rubber parts could be
recast. I have had
success casting rubber using Devcon flexane. It???s a 2 part mix with
extremely low shrinkage. The medium ???80??? liquid has a companion
softener flex-add which allow one to adjust the hardness of the
resulting rubber.
I have used Freeman machinable wax to make molds with good results. I
would think that with reasonable machining practice a run-out of a
thousandth or so could be had re-rubberizing a roller spindle. (A human
hair being about 3 thousandths of an inch)
If greater precision were required a machining allowance could be added
to the rubber and it could be frozen and ground after casting. (Not that
I would look forward to liquid nitrogen all over my south bend lathe,
and it???s not like we???re making disk heads here)
I don't think that much precision would be in order. I think as long as
the cast is made from an existing roller then a bunch of them can be
turned out in a short period of time.
I'm going to need to make a bunch of rollers for the various readers and
drives in my collection so I'll want to take this up at some point. Plus,
I've been wanting to find a project to try out the rubber casting kit I
saw at the local plastics shop and this seems like just the thing :)
--
Sellam Ismail Vintage Computer Festival
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