Acme Gear Cutter

[Video_Man]

Ran into a similar problem. The OEM spur gear only touched the lead screw on the edges, and wore over time so that the index marks were out of synch. 3D printed a helical gear matching the screws helix, works just fine. Should the OP have a 3d printer I can modify my .stl file for him if he has an accurate lead screw diameter, pitch, and number of teeth on the gear.

 

[Dan from Oakland]

If your thread dial is out of synch with the half nuts, simply shim the thread dial a bit to fix that problem.

 

[gbent]

What he said. Shim the thread dial away from the carriage.

 

[David_M]

 

[triumph406]

Personally I'd print the gear. For another project I bought some PETG+10%PTFE filament. Which seems to be very durable and low friction/stiction.

 

[triumph406]

Creating the CAD is quite easy with the right software.

This was a worm gear I did a few years ago in Cadkey99 (from the last century) and the DraftPak module. Because nobody at one of my customers could do it in SWX. Despite the fact allegedly they were power users.

Got made in China on a 4th axis. They only made 5 so didn't want to get it hobbed. Actually meshed like it was supposed too.

 

[EmGo]

This is a case where I'd go 3d print too. There's almost no load on the part, if it does wear out just make another, even if it only lasted a year, who cares ?

If op owned a hobber, sure, make it out of bronze but otherwise, plastic is fine. And if he doesn't have a printer, then buy one because they'd be fun to own. He'll use it for other stuff.

 

[David_M]

Creating the CAD is quite easy with the right software.

Or, you can make it hard like I seem to do:

Making one tooth to array into the worm wheel drawing.

The drawing in post #24 uses the dimensions found in this thread.