The springs keep the lobes of the cam expanded so that the cam stays in the rock. They are wrapped around the axles and hook onto tiny little machine bolts which are screwed into holes in the lobe. The trigger wires connect between the lobes and the trigger and are used to retract the lobes so that you can fit the cam into a crack. There are two sections: stiff rods (pictured above) that are inserted into the lobes of the cam, and tiny flexible cables that go from these rods to the actual trigger.
For the springs, we had some spring steel wire of the right gauge laying around, so I made a simple form with one of the axles, and just used a pair of vice grips to wrap the spring steel around. It took a little trial and error to get the windings tight and neat, and to get the tension right, but the result behaves just like the real thing.
For the springs, we had some spring steel wire of the right gauge laying around, so I made a simple form with one of the axles, and just used a pair of vice grips to wrap the spring steel around. It took a little trial and error to get the windings tight and neat, and to get the tension right, but the result behaves just like the real thing.
The first section of the trigger wire, a really thin flexible cable that loops through the hooks on the trigger, we just ordered.
The other part is a stiff rod that threads through the lobe, turns 90 degrees, and attaches to this thin cable. We made this out of some steel welding rod. Where the rod is inserted into the lobe, there is a peened 'mushroom' on the end of the rod that keeps it from backing through the hole. I used a ball-peen hammer to shmush the end of the rod into this shape, and it worked pretty well. For assembly, I stuck the rod through the lobe and bent it into an elbow, locking it into the lobe. Then I squeezed a small crimp around the rod and the cable to join them together.
The other part is a stiff rod that threads through the lobe, turns 90 degrees, and attaches to this thin cable. We made this out of some steel welding rod. Where the rod is inserted into the lobe, there is a peened 'mushroom' on the end of the rod that keeps it from backing through the hole. I used a ball-peen hammer to shmush the end of the rod into this shape, and it worked pretty well. For assembly, I stuck the rod through the lobe and bent it into an elbow, locking it into the lobe. Then I squeezed a small crimp around the rod and the cable to join them together.