I have been doing some threading in a toy lathe (Prazi SD300). It has none of the usual threading aids, such as threading dial, half nuts, leadscrew reverse, etc. It is a very tedious process.

The lathe has been modified to DC and variable speed. It will slow to a walk and stops instantly.

I previously made a revolution counter to wind coils using a Hall sensor and simple counter. I am now considering using the same approach to count turns and stop the lathe at a pre-determined count. I would then manually reverse, run up to the same count, etc. The on/off controls are typical momentary switches with relays, but are at full voltage (120 VAC).

Has anyone here done something similar, so I don't re-invent the wheel?

Thanks. John

 

I saw an exersizer counter, 4 dig LED disp @ $ 2.65 on All Electronics web, with customer comments on using for thread counting.

 

Since that project is now almost done -- imagine over 4 hours to thread a single, 11/16 - 24 connector. I needed two. I have decided to take a different approach.

While the Hall-based counter is good for winding coils, I have decided to go with hacking a Digimatic (Mitutoyo) scale so I can actually set an end point, rather than number of turns. I suspect I can get a more reproducible stop that way, which is not that important in itself, but it will also be easier for others to use as well. Just bought a Mitutoyo DP-7 miniprocessor on ebay and am anxious to get started. Unfortunately, April 15 is creeping up on us too.

Once I have a good feeling for the way it is coded, I will try to set up what I need on an MCU. Used Mitutoyo SPC-output scales are relatively cheap.

John