What is TPI and how to measure it?

[asayer]

Hello everyone,
first time poster, great forum.

Sorry to ask what is most likley a really silly question but what is TPI and how do I measure it?

I am getting back into wood turing after a 20 year break and talking to Carrolls about purchasing a G3 chuck for my old Golding lathe.
I gave them some spindle measurements but they are are asking:

Can you confirm if it is 1" X 8TPI or 1" x 10 tpi as golding came in both
Can you assist?

Thanks in advance

[texx]

TPI = threads per inch
you need to know the diameter of your shaft at the thread and how many threads per inch the shaft is threaded to:2tsup:

[jmk89]

tpi here is "threads per inch" and it is measured using a thread (or screw pitch) gauge - you can get a cheapish one from McJing (http://www.mcjing.com.au/categorybrowser.aspx?categoryid=251)

[asayer]

Wow thanks for the very quick responses.


Well from what Carrolls are saying I should be able to easily tell buy just putting a ruler to my spindle and counting?

[asayer]

Yep, counted and it was eight.

Thanks :2tsup:

[Ed Reiss]

right...so you've got 1"x8TPI.....easy:2tsup:

[Gil Jones]

This site has a good bit of data covering your question on TPI.
http://www.teknatool.com/products/Chucks/Identifying%20Lathe%20Spindle%20Thread.pdf

[asayer]

Thats great. Thanks again to all.

I have ordered my G3 and am very much looking forward to getting stuck into turning again.