# Finding wire diameter for thread pitch diameter measurement



## Thread man (Jul 23, 2022)

With this formula you should be able to find the best wire diameter for any thread - as long as you know the pitch and thread flank angle.

*A quarter the pitch divided by the cosine of half the flank angle.*

Depending on the thread lead angle there will be a small difference re "exact" but, if making a thread, the formula above is more than accurate enough.

_For those that have already looked and perhaps written it then I made a mistake. First time I wrote "Half the pitch"._


----------



## stevehuckss396 (Jul 23, 2022)

I have been using this calculator for a long time. After calculating the thread look at diameters and you will see wire. It gives you the ideal wire size and what the measurement should be. If you don't have that exact size wire then put what you have and recalculate and the new measurement will be given.






						UN imperial screw thread calculator
					






					theoreticalmachinist.com


----------



## Thread man (Jul 23, 2022)

stevehuckss396 said:


> I have been using this calculator for a long time. After calculating the thread look at diameters and you will see wire. It gives you the ideal wire size and what the measurement should be. If you don't have that exact size wire then put what you have and recalculate and the new measurement will be given.
> 
> 
> 
> ...


I always like those free calculators but re the one you like then the most common type thread in the world is metric.









						Thread Calculator
					

Find out the different cross-sectional dimensions of any metric bolt's external thread and nut's internal thread using this thread calculator, given the thread pitch, basic major diameter, and tolerance class details of the threads.




					www.omnicalculator.com
				




There are many but as to which is best is up to the user.


----------



## Thread man (Jul 23, 2022)

stevehuckss396 said:


> Message deleted


You've deleted. Maybe because you read again what I in fact wrote. Better late than never  I'm human (a least I hope so) so I make mistakes too.

_*"Take two identical coins and have them touch. Turn one of them around the circumference until back to the same point as you started. You'll find what should have taken one turn takes two. Regardless of the two circle diameters always add a 1."*_


----------



## stevehuckss396 (Jul 23, 2022)

I deleted because I mistakenly posted this in a thread about finding the correct wires to measure threads and couldn't find a way to remove it.


----------



## SmithDoor (Jul 23, 2022)

stevehuckss396 said:


> I deleted because I mistakenly posted this in a thread about finding the correct wires to measure threads and couldn't find a way to remove it.


I will delete for you 

Dave


----------



## SmithDoor (Jul 23, 2022)

Thread man said:


> With this formula you should be able to find the best wire diameter for any thread - as long as you know the pitch and thread flank angle.
> 
> *A quarter the pitch divided by the cosine of half the flank angle.*
> 
> ...


Most wire gauge sets have a chart with the set. For common threads after that there are formula in Machinist Hand Book.

Dave

FYI: Most time making odd thread I am making a both the thread and nut. At this point only need thread first the use the thread as a plug gauge to make nut.


----------



## stevehuckss396 (Jul 23, 2022)

I use it for the nontypical stuff. The hodgson radial has a fine thread in the cylinder something like 1-1/4 x 32. Don't quote me on that but it's not something you would find on a common chart. I cut and measured the thread on a "test" piece and used that to test the threads in the head. Then I used the best fitting head to test the threads as I did the cylinders. Everything worked out great because I was able to calculate and measure the threads properly because of the calculator. Even if I knew the formula I would still use it as a double check.


----------



## Bentwings (Jul 24, 2022)

Thread man said:


> With this formula you should be able to find the best wire diameter for any thread - as long as you know the pitch and thread flank angle.
> 
> *A quarter the pitch divided by the cosine of half the flank angle.*
> 
> ...


----------

