Part 3

After the lathe work was complete I had to Broach a keyway in the bore of the gear. A key is widely used in many applications. To explain; if you wanted a gear to turn you would need to use a motor to turn it. The problem is a round shaft comes out from the motor which then fits through the round bore in the gear, turn it on and the motor shaft would turn but not the gear. The shaft would just spin in the bore. To fix that, on the motor shaft there is a square slot an inch or two long. In the bore you make a square slot the length of the bore. Now you put a "key" which is a square metal piece say 1/4 x 1/4 x 2 inches long, into the slot and it makes it so the shaft can't spin in the bore. In many cases the metal for the key is weak, so if something jams up the key will break and not mess up the motor or the gear. To broach this keyway in the bore, I used a broaching tool. This tool is about 10 inches long, with teeth that are on a taper, as you force the tool thru the bore it keeps cutting deeper. You repeat this until the keyway is the right size. It is a job where you use muscle to force this thing through. Did one, then 4 more. Fun