Formula

mrbruce

Looking for the formula that gives the movement any particular thread size will move a object forward per turn ? I hope I said that right.....

1KYDSTR

I think that would be determined by the TPI? Cheap TPI gages can be picked up at Home Depot et al and you could use that to determine the Threads Per Inch. If it is 24 threads per inch, just divide the inch by 24 to get the forward movement in decimal form. I THINK that's right...still don't have any Cofee in me!

Tailgunner1954

Measure the thread pitch, or simply count the number of threads in 1 inch (TPI).

1/TPI = movement/turn.

Example a standard die has 14 threads/inch (7/8-14), 1/14 = .071" / turn. A micrometer has 40 threads/inch on it's spindle, 1/40 = .025" / turn.

mrbruce

Tailgunner,
I have a very good Starrett tpi gauge so coming up with the thread pitch is not a problem, I just would like to know how you came up with the amount a particular pitch moves forward per turn ???
It's a math thing and I never did well at that 'O(
I don't understand how you came up with these numbers, and that is what I would like to know....
1/40= .025 ???????
1/14 = .071 ???????

nononsense

mrbruce,

In order to determine the distance one revolution moves you have to take the one inch (1") and divide it by the number of threads found in that one (1") inch since the TPI stands for Threads Per Inch.

As an example, if you have a 1/4 x 20 bolt and you need to know how far one revolution will move linearly, you divide the one (1") inch by the number of threads per inch as shown by:

1.000"/ 20 (TPI) = 0.050" or 50 thousandths of an inch.

The slash (/) can stand for division without having to find the actual division sign in ASCII.

In TG's example of the 7/8" x 14 TPI you get:

1.000"/ 14 (TPI) = 0.071" or 71 thousandths of one inch.

I hope this helps rather than hinders...

Best.

robert574

Don't forget that metric threads (if you have them) are given directly by pitch.

For instance each full turn of an M10 x 1.5 thread will move the screw 1.5mm and the major thread diameter is 10mm.

A lot of firearms use metric threads but some are very close to english sizes (luck mainly). Best to use the correct match.

Tailgunner1954

quote:Originally posted by mrbruce
Tailgunner,
I have a very good Starrett tpi gauge so coming up with the thread pitch is not a problem, I just would like to know how you came up with the amount a particular pitch moves forward per turn ???
It's a math thing and I never did well at that 'O(
I don't understand how you came up with these numbers, and that is what I would like to know....
1/40= .025 ???????
1/14 = .071 ???????



Sorry, I skipped a logic step (my bad).
With a 14TPI thread, it takes 14 full turns to advance the fastener 1". Your question is (quite simply) how far does 1 turn advance the fastener? 1" divided by 14, (1/14") would be the fractional answer, punching the #'s into your calculator yields the decimal answer.

With any fraction your locking at a divide function in reality, so punching the numbers directly into your calculator will give you the decimal equivalent of that fraction.

mrbruce

Thanks alot guys, I have it firmly pounded into my head now, sorry it took so long.
The lack of a division sign was messing me up.
I might be slow but I'm sure 'O)