Gunsmithing quick question on thread depth , 18 TPI

[JJones75]

I was wondering if you can help me real quick?
I'm trying to draw up a small print and need the thread depth for 1.375"x18 TPI , I'm away from my books and for the life of me can't remember the formula for external thread depth

 

[Don Black]

Re: quick question on thread depth , 18 TPI

Double thread depth for 18 TPI is .o72"(.o36" single).

 

[300sniper]

Re: quick question on thread depth , 18 TPI

off the top of my head, for a sharp v thread the formula is: .866/thread pitch.

.866/18=.0481

if my formula and math are correct, .0481" should be the depth of a sharp v thread with 18 tpi.

 

[300sniper]

Re: quick question on thread depth , 18 TPI

here is the dimensions given in the machinery's handbook for a 1.375-18 3a thread.

major diameter max: 1.3750
major diameter min: 1.3663

pitch diameter max: 1.3389
pitch diameter min: 1.3353

minor diameter: 1.3068

 

[JJones75]

Re: quick question on thread depth , 18 TPI

Thanks guy , for some reason I cought a major brain cramp and could not remember the calculation.
Save the handy phone now