If anything, the second field test indicated the need for a specialized spanner to tighten the spring bundles.  We have been using a 15″ crescent wrench applied to the end of the cross bar with a cheater bar.  It takes 3 or 4 stout helpers just to stop the whole machine from rotating as the torque is applied.  Clearly this is a clumsy and thoroughly unscientific way of approaching the problem.   Some idea of the forces involved can be seen in the following photo.

A better approach will be to use the chain hoist attached to the end of the tightening lever and then back to the rear of the stock.   When we rig it like that,  the dynanometer can be used to measure the force and balance the bundles as closely as possible.  After an appropriate spanner has been made, that will be the next job.  The second field test ended with a rather wimpy shot.  This always happens after the bundles are tightened for the first time.  I had added another 22 feet of the 1/4″ spring cord for a new total of 275 feet per side, that is an 8% increase over what was there in the first field test.  That operation had left the bundles relatively loose.  It takes 2 or 3 cycles of tightening and shooting before all the easy stretch is taken out of the bundles.  Only then does the real power begin to emerge.   When we started to draw the bowstring back we were able to take some readings of the draw force and it appeared to rise a fairly consistent 100 lbs. per notch on the sideplates.   There are 23 notches in all (63 inches at full draw) and we were only able to take it to notch 14  (45 inches of draw) before running out of room with our ad hoc chain hoist arrangement. At that point the dynanometer was showing 1600 lbs.   With 9 more notches to go, and in a zone where most of the energy is probably stored, it will be interesting to see what kind of readings we get at full draw with bundles that have settled in after a few shots.

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