"William Bagwell" wrote in message
...

On Thu, 2 May 2019 15:02:46 -0700, Bob La Londe
wrote:

Since its new to me I figured I'd just use springs from my junk
collection and measure the force of the springs. Then order springs to
suit after that. I set up a little jig a while back to measure travel
of springs under weight on a platform for calculating spring force. I
was doing some airgun modifications. Its a pretty simple tool and easy
to make.

I never would have thought to look for "mold springs" or "square mold
springs." Thanks.

Since there is some heat in when injecting thermo plastics I was
concerned about spring life.

Rotational molds often use springs to even out the pressure of the
clamps holding the lid closed. They survive many trips through a
~400 degree Fahrenheit oven... Do eventually need replacing. And we
used both round and square cross section springs.

Used auto valve springs my son got for me at a junk yard for the one
mold I made.
http://alt-config.net/msbh/firstmold.html
--
William


*************
When I started thinking about heat affected springs I thought of automotive
valve springs as well. Might not hurt that I've been thinking about
hotrodding small engines lately, and one common requirement is putting in
heavier valve springs (to prevent floating a valve) when upping the RPM.