Hi. To carve the gear, the first thing is to calculate the gear data, and make a template that allows us to carve the gear.

In my case, I wanted some small gears, and one gear was carved from the right hand and the other from the left hand.

The ultimate goal: a 3D printer extruder.

You can see the videos in the last step.

Step 1: CALCULATE

In my case, I am going to carve the gear with an M12x1.5mm tap, one on the right and one on the left. So the spindle in which the gears are going to mesh will be threaded to M12x1.5mm, one part right-hand threaded and another part left-hand threaded. I used a workshop book, and decided to cut the gears with 18 teeth. So the reduction I will have will be 1:18.

Step 2: TEMPLATE

The jig has a 12mm reamed hole and has 18 scratches to use to carve the 18 gear teeth.On the other side it has two threaded holes, one threaded to M12x1.5 right and another threaded to M12x1.5 left. the distance of these holes from the 12mm hole is 9.8mm. This is important to be correct, because the depth of the gear teeth will depend on this. My advice is that you make the threaded holes before the 12mm hole so that when threading the male does not deviate.

Step 3: CARVE THE FIRST TOOTH

Turning the part that will be the gear. One part at 12mm and the other with a larger diameter, so that it stops. Make a line in the part with the largest diameter that will serve as zero.

Place the part on the template, place the zero on the one line of the template, clamp the assembly in a vise, and thread. In the photos you can see how, and the result.