Thread Cutting Guide?

[Tekno_Cowboy]

I seem to recall a few post a while back with links to thread cutting charts, indicating how much to advance the tool for each pass for 29.5 degree and straight-in threading.

Does anyone know which thread that was? I've been looking for an hour and can't seem to find it. :thinking:

 

[jhanko]

I think this is what you're looking for...

 

[gadget_lover]

I know the one you are talking about, but I don't see it anywhere either.

When I looked at it, it seemed to be (simplified) 1/2 of the remaining depth for each pass.

I found this page that said:
Number of Passes:

To determine the number of passes for most 60-degree threads, use this formulas:

Number of passes = ( 72 x pitch ) + 4
example: thread = 8 tpi
pitch = 1/8 = .125
Number of passes = (72x.125) + 4 = 13
Thread depth = 0.078125, so about .006 per pass.