DaveDDS wrote on 2025-12-10, 11:04:
Hard to tell for sure looking at the photo, but it seems the problem is the smaller of the two gears, which (you glued?) has a wider area around one of the teeth which now gets jammed into the teeth of the larger gear as they rotate together?
I'd probably take a very small triangular file and see it I could pair the enlarged tooth area down to fit - very little bit at a time, you want "just enough" as you want as much of the glue remaining for support as possible.
You should be able to feel it bind as you manually move the mechanism, so I'd go just enough to have it move fairly freely.
I would second this, with a small alteration.
It's possible to 'ghetto fab' a replacement gear from a suitably durable material that can stand up to being filed to mate up correctly.
There's a very old video on youtube for 'protoputty'. It's basically 1tbs or so of water, whipped into the vinegar smelling type of silicone bathroom caulk, then mixed with cornstarch until a kneadable 'dough' is made.
It's great for making simple impression molds for 'prismatic' items like gears.
Coat the source gear with a thin coating of light oil so the putty wont stick, then press it into the prepared putty to make a simple impression mold of the 'fixed' gear.
Once the putty cures (24hr), just bend the mold and pop the gear out.
Then, mix some slow setting 2part epoxy, and pour it into the mold. Wait the prescribed cure time, then file the resulting gear into the correct geometry.
This new ghettofab gear will be strong, and not prone to break like the glued gear would be.
(Note. Plastic gears are usually made of nylon, and have a teeny bit of flex in them, and very hard materials like clear epoxy might be harmful to their mating gear. 'Plastic weld' from JBWeld is a 'much softer, practically gummy' epoxy that's creamy offwhite in color that may work better as a FINAL product. That is to say, make the hard gear, file it to fit, then repeat the process of mold making and cast a plastic weld gear out of that for final use.)