Assembling the jacks

So far, I've assembled a couple of prototype jacks in testing out the jack design. Now that the process is being done for real with actual jacks, here's the procedure.

First, any burrs in the jack body caused by drilling the axle hole are trimmed with a small chisel:


Next, the axle hole in the tongue is enlarged with a miniature reamer:


The looseness of the reamed hole is checked with an axle pin held in a pin vise. The tongue should hang down freely under its own weight:


The jack is temporarily assembled to check the fit of the tongue within its slot:


If necessary, the tongue is sanded a little to narrow it for a looser fit:


Once again, the tongue should hang down freely under its own weight:


3 mm strips are cut from a sheet of 0.005" brass shim stock to make leaf springs:


Individual 19 mm long springs are cut from the strip and slid into the spring slot:


The 3 mm width was chosen to make the spring fit snugly within the slot.

Each spring is pre-tensioned by bending it forward:


Finally, the jack is reassembled:



Each assembled jack is tested to make sure the spring returns the tongue fully to the forward position. At present the springs are stronger than necessary, but they can be adjusted later by bending them back slightly.