just an idea, have you enabled

Config -> Ports&Pins -> Spindle Setup -> Use Spindle Feedback in Sync Modes
Config -> Ports&Pins -> Spindle Setup -> Spindle Speed Averraging

Yes, both of those are checked 

not sure you have this?

https://www.machsupport.com/wp-content/uploads/2013/02/Mach3_Threading.pdf

not sure you have this?

https://www.machsupport.com/wp-content/uploads/2013/02/Mach3_Threading.pdf

Yes, read through it. Didn't seem to help with with setting up the sensor.

I'm hoping the sensor is broken (or not working proper, like the rest of this lathe was when I got it lol). New sensor on the way, will install and test when it's here.

Current one come with the lathe, nothing worked which is why I got the thing dirt cheap and I've rebuilt everything. Never could get the sensor working so I've just been cutting without it (since it's a gear box lathe). But I want to try and thread some stuff now and well it's needed haha!

Cheers

Kyle

Got it working!

Sensor shows within 1-2 RPM of what the gear box chart reads which is awesome.

Thanks for the help everyone, the sensor was the issue 😎

- kyle