On Sat, 21 Mar 2009 23:54:25 GMT, Dan@ (Pirateer guy) wrote:

I need to make a part out of rubber. The part is obsolete and cannot
be purchased. I have one, but it has shrunk over the years and is now
loose and it leaks water.
The part is an isolation ring for a boat engine mount. It sits between
two pieces of aluminum and is compressed by the two pieces.
This allows some movement between the engine and the engine mount and
it also seals out the water.

I am thinking that I can use the existing part to make a mold to build
a new part out of urethane. I can add bulk to the existing part to
make up for the shrinkage.
Problem is, all I can find on the web is urethane for making the mold
not the part. Does anyone have any insight into how I can do this?
Fairly complex part, but I have one to make the mold from.
The link is to a parts manual that shows this part. It is on page 14,
of 20 and it is Item Number 8. It is OMC part number 322214or OMC
393162. same part.
Thanks everyone
Dan

I've not had a lot of experience with this but have made (hard)
urethane parts using a silicone moldmaking material. Silicone is
great because mold release normally is not needed; almost nothing
sticks to silicone.

You might find that a moldmaking urethane can be used as a casting
material. Though most moldmaking rubber is quite elastic to allow the
pattern to be removed.

Bought my supplies from http://www.polytek.com . They have a pretty
wide variety and reasonable prices.

Best -- Terry