RLBailey_at_care4free.net wrote:
>
> I tried stretch testing motors of F1D size to assess quality but found
> that the knots, which work OK when winding, repeatedly fail on stretch
> testing. I found it easier to test via winding since I could get much
> nearer to maximum and therefore abandoned the stetch method.
>
Yup, the knot is a problem. Also when testing and breaking in F1B
motors. For several years every one or two motors out of 10 failed
during the process, many of these from the knot, that cut trought the
ruber and then broke away. When one strand of a fully stretched motor
fails, the motor starts to unwind, and the strands cut trough each
other, making the whole motor unrepairable. Eventually I found a knot
used by Bror Eimar, "norsk strykknute", that can stand the pull of the
test. This knot needs to be tied into lubed motor, in unlubed rubber the
knot will cut and damage the strand. However, I have found that when
using proper thick silicone for lubing is too slippery and the knot will
slip, instead I need to use thinner (1000 cts) silicone for lubing the
know, this stuff lets the knot slip when tightened, but then lets the
knot "stick" when tight enough.
-Tapio-
- application/x-ygp-stripped attachment: stored
Received on Sun Mar 08 2009 - 12:26:20 CET