In this video we see some temporary tuning templates that greatly simplify keeping track of the rotational torque applied to the bundles.  tuning A series of four shots was fired with each shot having the washer rotation increased by the minimum increment available of 7 1/2 degrees.  Here is a vid of the first of these shots;  note the firing chain now in use to connect the sear on the trigger block back to a more comfortable firing lever at the rear of the machine.  20100126132809

The four shots tried today proved conclusively that nylon  double braid is utterly unsuitable for making torsion springs.  It makes sense really.  All those strands weaving back and forth, criss-crossing over one another,  may well make an extremely strong rope, but the internal friction it creates deadens it’s usefulness as a spring.  The velocity of the four shots was 173 fps, 184 fps, 228 fps and 185 fps.   Wimpy in the extreme for a bolt weighing a mere 5,000 grains.   The last shot of 185 fps had been given an extra 7 1/2 degrees of rotation just like the others, and yet the velocity dropped back down again.   The larger 3/8″ diameter rope and it’s double braid weave, are clearly unstable power generators and are a far cry from what the 1/4″ twisted 3  strand could do.  New springs of this latter type are being constructed and that should get us back on track again.  The ultimate extension of this logic suggests that a spring built  up from  small diameter thread, much like Mr. Gallwey advocated, would have the least  internal friction, and probably allow the greatest amount of spring cord to be fitted in the field frames.   (Note to self:  You have no choice.  Quit being a poltroon and learn how to wind up springs using a couple of miles of nylon thread.  How bad could it really be?    Remember,  beeswax is your friend.  Err!)

The good news is that all the mechanical parts of the machine are now  standing up to the heavy 3500 pound draw weight with ease.  The new bottom  struts, visible in the above photo,  have given the machine much more stability under load.  Similarly, the hardened vernier plates are working perfectly to counter the bending forces attempting to collapse the end caps on the field frames.  All in all, I am very pleased with the overall robustness of the machine.

Empirical research of this type does leave one feeling a bit like a blind rat bumbling around in a maze.  It does, however, yield results that are sometimes unequivocal.  Springs made from double braid are bad.  Very Bad.  Might as well use linguine.

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