You can “build up” the last tooth up to a 2 gear teeth span (from the last tooth).

After the welding phase dip the red hot part of the gear in mineral oil to temper it. Dousing it with water will make it brittle and we don’t want that happening….while letting it cool down slowly will make it soft… we also don’t want that to happen.

When the welded sector gear is cool enough to be handled. Securely grip the sector gear into the table vise clamp and start grinding (be sure to wear safety goggles when doing this) the welded last tooth of the gear into shape, using a hand grinder. Carefully grind the welded last tooth removing the excess metal and blend it with the original gear thickness and roughly the same height.

After achieving the proper thickness and height. Carefully shape the welded part into the proper gear height by using a file. This takes up some patience and skill, and I never said that this procedure is going to be easy; you got to either have the skill or had a lot of practice. What we are trying to achieve is here is to shape the welded last gear tooth into something that resembles a shark’s fin...

Note:

While hand filing, be sure to get the proper “space/clearance” between the last and second to the last tooth. To check the gear tooth spacing, set the gears into the gearbox/mechbox to see if it meshes properly with the piston body and to see if none of the welded part touches any part of the gearbox/mechbox by spinning it manually (I also have a piston body close while filing to check the gear tooth spacing while filing it into shape). I everything meshes like it should and it spins freely with the other gears (spur, bevel gear) then you got the clearances right.

Check the reinforced sector gear tooth if it meshes properly to the piston body teeth. If everything looks good and it meshes properly then it’s done and ready to be tempered and cleaned before installation.

Temper the welded last tooth by carefully heating it with the acetylene torch till its red hot, then dipping it in mineral oil or used motor oil. After this is done, clean the carbon of using detergent and fine copper wire brush. After this it is ready to be installed.

Shim and lubricate as you would shim any gear set.

The added/extra material on the last tooth on the sector will provide added support when it is under stress, preventing it from breaking off. While the “hard facing” welding rod material and tempering will provide material hardness preventing it from wearing out prematurely.