I have been fooling around making a list of the diametrical (DP) pitch and modules (Mod) of gears.
DP is imperial and Mod is metric.
To make a list if the thread pitches on the lathe that will cut these I have to go through all 600 some odd settings and find them.
To do this I have to find the circular pitch of the DP, this is the distance from one tooth to the next.
Once I get that I can take a tread pitch TPI divide that into 1.000 and it will give me the distance from one thread to the next.
This I then match up with the circular pitch of a given DP pitch.
This is all going on a list.
An example is a metric module of 1.5 it took some doing to get it and my end gears in the lathe are a module of 1.5 the equivalent of a DP of 16 but not exact.
Plus I had to convert the MM to imperial to get another answer I needed.
So I found the gear set that would cut this module and it drove me nuts because I cant disengage the half nut cutting metric.
Then I got the bright idea of going back on my list and seeing a gear set that I can cut imperial and disengage the half nut.
Here is the 1.5 Mod setting. after I had my answers this distance between the teeth are 0.1851 this is as close as I can get I think this one is dead on with my lathe.
The 5.5 thread pitch setting on my lathe will cut a lead/pitch of .1818 distance between threads.
This is a difference of .0033 not enough to amount to a hill of beans.
Here is a pictuer of the test the cutting tool isn't exact and the thickness of the pipe wont let me go to full depth.
The top one would be a 25:1 ratio and the bottom a 60:1 ratio if it were a worm drive and worm wheel.
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