Over the summer I bought a box of taps , the seller thought the owner might have worked for the railroad.

I put it in the "get to it" pile and forgot about it.

Tonight I was looking for a tap and opened it up.

Now, I have been around tools and screws and bolts all my life and thought I had them pretty well sussed out.

BUT

some of these sizes are very odd to me and I am trying to get a handle on what the previous owners profession might have been.

the odd( to me) sizes are 10-30, 20-20,  6-36, 14-20, 8-36

My guesses are:

gunsmith , a couple of the taps say "gun tap",  do smiths use different sizes than regular people?

repaired gauges and industrial valves

medical equipment

worked for DR Frankenstein during his 'small people' years

any ideas?

Thanks

Skip

DSCF2890 by Skip Albright, on Flickr

DSCF2891 by Skip Albright, on Flickr

A lot of bench planes use very odd thread pitches, but it's hard to imagine a shop in which this many repeats of those pitches would be needed.

There were a lot of odd (by today's standards) thread sizes back in the day. All of the sizes that you mentioned except the 6-36 comply with an old American Society of Mechanical Engineers (ASME) standard that was adopted in 1907. The standard lists number sizes from #0 (.060)  thru #30 (.450). When encountered on old machinery some of these sizes can pose a real problem as they are close to today's sizes in diameter. For example #14-24 measures .242 dia, #16-22 measures .268.
Don't try jamming a 1/4" screw in there.

Joe B

I watch a You-Tube channel by Keith Rucker. He works part time at a Museum restoring old machines. He was talking one day about needing a 1/2 x 12 NC tap for a job he was working on. He was saying that years ago that many companies used odd thread sizes when building stuff. 1/2 x 13 NC is a common size and fairly cheap to buy. 1/2 X 12 NC is not common to find and is expensive when you do. If you were to look up current prices on some of those older odd size taps and dies you might be shocked at what they cost. I am going to be relocating all my taps, dies, drill bits, reamers and easy outs in to one tool box instead of several different boxes. I have stuff i have bought in the last 45 years and there might be some surprises
for me.

EvilDr235

Quote from: EVILDR235 on January 05, 2017, 03:40:30 PM
I watch a You-Tube channel by Keith Rucker. He works part time at a Museum restoring old machines. He was talking one day about needing a 1/2 x 12 NC tap for a job he was working on. He was saying that years ago that many companies used odd thread sizes when building stuff. 1/2 x 13 NC is a common size and fairly cheap to buy. 1/2 X 12 NC is not common to find and is expensive when you do. ......
EvilDr235

I think 1/2-12 was a common thread at Brown & Sharpe.

Old fastener catalog that I have show either 12 or 13 tpi as common for 1/2" . Kinda' strange how this situation came about. Perhaps one explanation is that the Whitworth (British) standard for 1/2"dia thread is 12 tpi. That standard had been in place a long time.

Joe B

I can just imagine walking into the ACE hardware store and asking the 17 year old girl working where i can i find a 1/2 x 12 NC bottoming tap. SECURITY, SECURITY, we got another old nut that escaped from the nursing home.

Gramps.

Just a thought could the person have been a sharpening taps for profit? Collected them for future sales?

My best friend came by yesterday wanting a 1/4" X 24 bolt.   I gave him one  :)

Quote from: bgarrett on January 19, 2017, 04:16:48 PM
My best friend came by yesterday wanting a 1/4" X 24 bolt.   I gave him one  :)

That's an odd one.
Where did YOU get it?

Just a word of caution on that supposed 1/4 - 24. that size does not show in any of the old standards that I see. Most likely what you have is the ASME standard   #14-24  that measures .242 major diameter....close to 1/4" but "no cigar"

Joe B

I just gave a friend some thread dies of unusual sizes.  They were all three marked GTD (Greenfield).
5/8-12    NS
5/8-24    USF
1/2-24   USF
Anyone know what NS and USF mean?
Al

NS = National Standard

USF   United States Fine, just a guess!!!!!!!

USF= Some confusion whether United States Franklin or United States Form.
NS = National Standard, now called Unified National Standard, UNS.