What size and thread are Torrington pedal block nuts?

[bloo]

Well I already tried a Schwinn chain tensioner and it doesn't screw in. That is another screwball thread I would like to know the identity of. It would have come in handy a couple of days ago when I was repairing one of those screws.

 

[WetDogGraphix]

I take it the 12-24 was too large.....
I took my 10's apart.....Using my dies on the bolt, the 12-24 was too large, the 10-24 was too small..
On the nut, using a tap, the 10-24 went in, but was loose....sooooo, I have no answer

 

[JLF]

Considering vintage road bikes for a moment, you don’t suppose they would have used French, Italian, etc threads?

 

[bloo]

Maybe the same as some 7/32” hardware, (e.g., chain tensioning screws); I believe that they were off of the #12 size by a few thousandths of an inch.
And then there is the number of threads per inch, (ugh).

You may be on to something with 7/32". It measures 7/32".

Found my thread gauges and it APPEARS to be 7/32"-28tpi. Or maybe #12-28tpi. It's not metric.

This confuses me because I thought I tried some #12-28 fastener at the hardware store. I'll have to do that again to be sure. 7/32" should be 0.219 and #12 is 0.216" major diameter. Maybe its really 7/32" and the .003" was enough to make it not screw on?

I found these..... https://www.tracytools.com/7-32-x-28-tpi but there are no specifications listed. I found no other evidence that 7/32"-28 even exists.

Any of you guys got a machinerys handbook? I can't find mine.

In other news, the Schwinn chain tensioning screws are 24tpi and measure about .243 major diameter. They are kind of beat up, and aren't terribly tight in the frame. I think it's a fair guess they were born as 1/4"-24tpi, halfway between UNC and UNF.

 

[Archie Sturmer]

I believe that pre-war or so, Shelby may have used 26-tpi chain tensioning screws.

I believe 26-tpi was a British Standard Cycle (BSC) thread. Tracy may also have 26 tools, but I'm not sure which is right.