hello all.

was hoping someone could clear this up for me.. the thread cutting table on my lathe shows inch-threads in fractions.

for example:

1/16

19/512

11/28

9/256

etc..

i needed to cut a 20tpi thread today.. and my thoughts went like this: 20tpi is 20 threads per inch so 1/20 is about 0.05 inches per thread. i dialed in 13/256 because 13 divided by 256 = 0.050

i ran a skim cut (scratch!) and it *looks* about right. i dont want to take the plunge and screw up the job.

am i using the table right? why doesnt it just read "20 tpi" ?? are they fractions that i should be dividing?

i do metric 99% of the time (i'm in europe) and the metric tables tell me the pitch directly. (1, 1.25, 1.5, etc)

anyone shed any light?

thanks!

-knucklehead

ps.. the lathe can also do "D.Pitch" threads.. anyone know what that means?

was hoping someone could clear this up for me.. the thread cutting table on my lathe shows inch-threads in fractions.

for example:

1/16

19/512

11/28

9/256

etc..

i needed to cut a 20tpi thread today.. and my thoughts went like this: 20tpi is 20 threads per inch so 1/20 is about 0.05 inches per thread. i dialed in 13/256 because 13 divided by 256 = 0.050

i ran a skim cut (scratch!) and it *looks* about right. i dont want to take the plunge and screw up the job.

am i using the table right? why doesnt it just read "20 tpi" ?? are they fractions that i should be dividing?

i do metric 99% of the time (i'm in europe) and the metric tables tell me the pitch directly. (1, 1.25, 1.5, etc)

anyone shed any light?

thanks!

-knucklehead

ps.. the lathe can also do "D.Pitch" threads.. anyone know what that means?

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