Connection nut thread size

Per the Machinery Handbook there are two American Standard threads in #4, the course #4-40 and the fine #4-48. Hope this helps.

It’s an oddball, 4-36, which is a near forgotten machine thread,….

Pat

I think Lionel had the 4-36 made specifically so you had to buy the nuts from them!

Forgotten perhaps but you can buy them online from the former bookseller that now sells everything.   100 pieces for $3.90 + $9.95 shipping.

@Danr posted:

Forgotten perhaps but you can buy them online from the former bookseller that now sells everything.   100 pieces for $3.90 + $9.95 shipping.

Jeff sells everything!..,..I think threads that small that are more obsolete than what we see today beckon back to the time of National Fine, & National Coarse, ……when men cared about important things, ….like TPI …..😉

Pat

Having been in the aerospace manufacturing business my whole adult life until retirement it’s amazing how many so called machine shops, large and small, no nothing about thread class and don’t know how to perform the proper verification of a thread.

@Trainmstr posted:

Having been in the aerospace manufacturing business my whole adult life until retirement it’s amazing how many so called machine shops, large and small, no nothing about thread class and don’t know how to perform the proper verification of a thread.

I’ve hired & fired so called techs that had more patches and awards than a North Korean general, ….they couldn’t tell you what grade a fastener is, let alone anything to do with threads,…..if you can’t identify simple grading marks, you have no business touching something that can propel itself down a road towards other people ……

Pat

Lionel used a lot of #3 screws. I get a selection from the screw guy at York.

4-36 thread was basically obsoleted after WW2. Called a clockmakers thread, it was replaced by 4-40 finer thread by the S.A.E.

Interesting that Lionel kept the 4-36 thread on binding posts to the very end. Early in the MPC era they switched to metric threads.