I've 3D printed knobs using 1/4" brass inserts with a set screw for the
shaft. The inserts are knurled on the outside and you use a soldering
iron to get them hot enough to press into the shaft hole on the knob.
It works very well, and you get a recessed set screw for a tight
connection. The downside for using it on a gear is that you need to
have a small hole for the set screw, but if the gear is wide enough that
might not matter. It's possible, though, to get a very tight fit even
without an insert.
55 teeth could be dicey to print on a 7/8" OD gear, but the precision of
a good 3D printer is pretty amazing so it could be possible. I use a
modeling program called OpenSCAD and it creates 3D objects using code
statements for geometric shapes, which makes it great for parts like this.
If N4TZ can send me some close up pictures with precise dimensions it
might be fun to give it a try. No promises, though. The biggest
concern I have would be getting the profile of the teeth correct.
I have an FDM printer (extrudes thin strings of melted plastic to build
up layers) and I can print with either PLA or PETG. PLA is harder but a
bit more brittle. PETG is more flexible, but it is tougher and seems to
be more slippery.
To be clear, I have no intention of doing stuff like this for money ...
nor for doing a lot of it. This would simply be a one-off effort to
help out a fellow ham in need. Somebody could probably try to make a
business out of it, and the material cost is peanuts, but I question
whether the time spent making custom parts could generate a decent
financial return.
73,
Dave AB7E
On 1/6/2023 9:18 AM, john@kk9a.com wrote:
Good luck with finding one. There are many gear suppliers online but buying
a small quantity is challenging. I would try McMaster-Carr. Maybe another
option is 3D printing if you have solid modeling software. Make sure that
the plastic gear is tight against the rotating shaft to prevent slippage and
wear. I put a screw in the side of my housings to keep the potentiomenter
bracket in position. About a decade ago I needed a couple of the steel
gears that fit on the 10mm windshield wiper motor shaft and was unable to
purchase them, at least not for an affordable cost. I wound up having to
buy gear stock and machine them myself on a lathe.
John KK9A
Zivney, Terry N4TZ wrote:
Does anyone know of a source for the small plastic gear that fits on the
multi-turn pot inside the Tic-Gen ring rotor motor box? The one that lost
some teeth
had 55 teeth, was 7/8 inch OD and had a metal insert to fit the 1/4 inch
shaft of the pot. I have a replacement from the pot removed from a
slave motor which didn't need the position indicator, but I would like
to have a replacement for just in case. These motors were late 1990's
vintage, with the sheet metal box, and the 1022 size ring.
I don't want to have to go to the external pot assembly TIC-Gen uses now.
Terry N4TZ
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