I am looking for some parts to make a micro syringe piston tank using a BBQ injector. But the issue I am having is finding a gear that is threaded on the inside to lift my nylon threaded bar. Could some of you suggest somewhere where I could find some stuff like that? Or at least what its called.

similar to this set up.

Mini RC submarine ballast tank test 2 (0 min 27 sec)

Trying to get my supplies together to convert an academy 1/150 boat. And I figured I could just stick a radio in it and link the control surfaces and dynamically dive it... but whats the fun in not challenging yourself

Thanks ahead of time

How about using a metal nut that will fit your threaded rod and embedding the nut inside a plastic gear?

Stock Drive Products www.sdp-si.com has a vast array of gears ect. that should help.
Also try calling Precision Scale Model Engineering( the web site does not show the catalog)

How about using a metal nut that will fit your threaded rod and embedding the nut inside a plastic gear?

That's what I plan on doing if I cannot find anything else. And does metal on nylon offer better results? Just curious that statement made me wonder :P

Thanks for the help so far!

Looks to me like he has just drilled and tapped the main gear with a thread. Usually piston tanks use a metal spindle and spigot. For a small tank like this, you can get away with plastic.

best bet is to drill and tap, otherwise its a huge pain to get the nut centered on the gear properly.

This may be a crazy idea, but how about scavenging parts from a screw type deodorant? I took one apart the other day and it looks like the parts are similar to what you’re looking for. That is if you looking for a DIY solution.

hmm I ll look at one I like the idea! thx for the suggestion. I built a prototype but its belt drive... aka rubberband. and I need gears now. I just bored out and tapped a gear. Used a bearing to hold it in place and a brass screw.

Parmesan cheese with built in grater also has a nice mechanism.