> In a message dated 10/5/2005 11:50:11 PM Central Standard Time,
> ryoung@navcomtech.com writes:
> > Might be worth noting, in case anyone else wants to try this, that the
> > castable
> > polyurethane comes in many different hardnesses as well. As I recall, there
> > were formulas from 40 shore (which is about the same as the EPDM 'rubber'
> > bushings) to over 90 shore, which is very hard, almost like wood.
Dave Massey replied :
> Would that be Shore A or Shore D?
> (see http://www.machinist-materials.com/hardness.htm )
It appears the answer is "yes". I was thinking Shore A, but a quick Google
turned up
http://www.polymerestechnologies.com/EN/molding.html
who claim to have products from 5 Shore A (about like jelly) to 95 Shore D
(which is much harder than most rigid plastics, for example Teflon is 50-60
Shore D and Nylatron GS is around 85 Shore D).
Because of the difference in testing methods, it's my understanding that it's
essentially impossible to compare Shore A hardness (which is normally used for
"rubbers") to Shore D hardness ("plastics"). This can be seen on the web site
Dave quoted above, where one chart shows 95 Shore A to be about 55 Shore D,
while the other chart implies 100 Shore A is 0 Shore D. There's more
information at
http://www.matweb.com/reference/shore-hardness.asp
Randall
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