To adjust the spring tension on our catapult we have a CIM with a 5:1 VersaPlanetary Gearbox. The lead screw is attached to the output of this gearbox with a shaftcoupling. We use a 10TPI single lead Acme Screw. We have a moving carrier block driven by the leadscrew which adjusts a lever arm (green). The carrier has 10" of travel. The upper 4 springs are suspended from a pivot on this lever arm (red). The lower 2 springs have fixed rear mounts and are not dynamically adjustable. We measure the position of the carrier block with a 12" string Potentiometer. THis allows us to adjust the shot from 10' to 50'. This setup has served us very well.
FIRST: The hardest thing you'll ever love to do. - Stephen Kowski [more] 
15-05-2014, 14:00
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