7/32-40 tap?

I just remember that #5 is .125, then add or subtract .013 for each number up or down. No idea about the history of it....

Bob

Could be Model Engineer's thread. This will be 7/32" 40tpi 55 deg angle.

see:-

Probably far from common in the US of A though.

Mark Rand RTFM

It is in Machinery's Handbook. You start with 0.060 and multiply each integer above by 0.013 and add result to 0.060. For very small sizes you start with 0.060 and subtract 0.013 for every zero in the size description. For example 00-90 would be 0.060 - .026 = 0.034 with 90 threads per inch.

You're almost right, Robert. You subtract .013 for each zero in addition to the first. An 0-80 is .060. A 00-90 is .060 - .013 or .047. A diameter of .034 would be a 000-(something).

Jerry

description.

More likely National Special!

Steve R.

You are right!

Gun tap. Brownell page 167 #080-598-112 Price $ 69.27 Thread used for peep sight apertures.

MrBill,

You win points for guessing what it is for. You loose points for giving a partnumber for a die. ;)

Wes S

x?]QÁn1½ïW

No kidding? I never knew that. Thanks!

Gunner

"The importance of morality is that people behave themselves even if nobody's watching. There are not enough cops and laws to replace personal morality as a means to produce a civilized society. Indeed, the police and criminal justice system are the last desperate line of defense for a civilized society. Unfortunately, too many of us see police, laws and the criminal justice system as society's first line of defense." --Walter Williams

D'oh! If whoever was looking for this just needs to borrow it I can see what shape mine is in. Inherited collection so it varies. But I know I've got the tap.

Anti-metric :) Randy

The current U.S. number series threads are the Sellers series threads after the guy that made them up in the mid-1800's. He managed to get the railroads to adopt them before they became a national standard. I've no idea as to how the sizes and thread pitches were originally determined. Might be some googling is in order.

As to your thread size, this might be one of the Model Engineer threads, those were all 40 t.p.i., IIRC. The series was originally designed for live steam models by the staff and contributors of the Model Engineer magazine. You might have to go to a Brit publication to find it, it's probably not any U.S. standard.

Stan

That'll be because the thread is 2BA not 3/16 :-).

Mark Rand RTFM

==================== Engineers & designers love standards --- thats why we have so many of them.

Looking forward many years after metrics have become universal

--- will we see somone trying to find a 1/4X20 tap???

Unka George (George McDuffee)

There is something to be said for government by a great aristocracy which has furnished leaders to the nation in peace and war for generations; even a democrat like myself must admit this. But there is absolutely nothing to be said for government by a plutocracy, for government by men very powerful in certain lines and gifted with the "money touch," but with ideals which in their essence are merely those of so many glorified pawnbrokers.

Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.

Dave,

Thanks for the kind offer but I hope I have the right one of my one on the way.

Wes S

I've heard it called 2BA. Fwiw the 3/16-? tap I had worked okay but then there are not many threads of engagement on a dart shaft.

Wes S

here's the data (might need a fixed pitch font for it to line up)...

Thread Dia/ Dia/ Pitch/ Pitch/ Core Core Depth/ Depth/ Name Inch mm TPI mm Dia/" Dia/mm Inch mm

Included angle=47degrees

Was a standard electrical and instrumentation thread in the UK and colonies before ISO metric supplanted it.

Mark Rand RTFM