How to thread 1/2 13 threads pm1236

[FTlatheworks]

I don’t think I have the proper change gears with my lathe. Can someone help me set my pm1236 up to cut 1/2 13 threads? I have it set to what the chart says, but it cut very fine threads. I think I need to change gears, but I don’t have 48 tooth gear I have a 44.

 

[rock_breaker]

Is your machine equipped with half nuts? I am not familiar with your machine at all but wonder if you are using the machining gears in the carriage as opposed to the half nuts when trying to make your threads. Just a WAG.
Have a good day
Ray

 

[FTlatheworks]

Is your machine equipped with half nuts? I am not familiar with your machine at all but wonder if you are using the machining gears in the carriage as opposed to the half nuts when trying to make your threads. Just a WAG.
Have a good day
Ray

Yes, I’m using the half nuts.

 

[FTlatheworks]

Whichever you are supposed to use for threading. Idk the proper name. I’m not using the carriage power feed, but a separate lever only for threading.

 

[Mitch Alsup]

The Grizzly manual for the lathe with the same gearbox indicates you need the gears to be::
a = 60
b = 78
and the dials set to:: AD1V

 

[darkzero]

By default (how the lathe ships), the 24T gear is installed on top & the 48T gear is on the bottom.

Install the 48T gear on top (in place of the 24T) & install the 26T gear on bottom (where the 48T gear was).

Your dials are set correctly for 13 TPI (C, 3, M1), as long as you have the 48T gear on top, meshing with the 127T gear & the 26T gear on bottom meshing with the same 127T gear you should get 13 TPI.

If you did not change any gears (default), setting the dials to "C, 3, M1" should have gave you 48 TPI for your test cut.

 

[FTlatheworks]

Ya it was definitely 48. Where I’m confused is the z? The diagram shows that bottom gear as z, not 48.

 

[darkzero]

Z indicates the gear you install from row Z on the chart to give you the different thread pitches listed under the gear numbers specified in row Z.

For example, the lathe ships stock with the 24T on top & the 48T on bottom, both meshed to the 127T. So in this configuration you are able to cut the follow thread pitches: 16, 32, 18, 36, 20, 40, 24, 48, 28, & 56 just by changing dials.

All the other thread pitches you'd have to change gears around. And for metric threads, the bottom gear has to mesh with the 120T instead of the 127T, The top gear will always mesh with the 127T.

 

[FTlatheworks]

What are the top two charts signifying then? They say imperial lead screw and metric lead screw. How can I utilize those?

 

[darkzero]

The top 2 charts are feed rates using the power feed rod, not the leadscrew/half nuts, dial set to "S". The chart indicates travel in millimeters per one revolution of the spindle & travel in inches/imperial per one revolution of the spindle.

The squiggly icon is not representing the leadscrew. The horizontal squiggly icon is for the carriage feed rate, the vertical squiggly is the cross slide feed rate.