Rectangular cotter holes
Posted: Thu May 09, 2019 11:58 am
RRs are not always know for the simple approach, why have a round cotter hole when it is so much more challenging to have rectangular ones. A hundred plus years ago, some party in authority at the D&RG narrow gauge had the strange idea to use rectangular cotters. Not sure if any other RR did this, I have not seen any elsewhere. Between the journal box covers, brake shoe pins and brake rigging, there are at least 24 such pins on a typical D&RG vintage freight car.
Pretty sure EDM s were not popular 100 years ago, so it had to be a bunch of cheap apprentices making the holes. Anyway after looking at some of the original pins, I was confident it was a hot punching approach. I conjured up a punch and die set and the first run was 5/8” dia pins. Next batch is ¾” dia. Fortunately all pin sizes use the same size cotter. Die was showing a bit of drag after the 10th pin so I was thinking may have to alloy face it, or redress after every 10 pins. Then after cleaning the die, enlarging the waste hole, and applying a bit of never-seize every four or five pins, it popped out another 20 with no problem.
Success, Really happy when the press came down and there were no unexpected crunching sounds. We try to stay authentic at the museum and this was a good exercise.
These pins hold the journal box covers, next set was the ¾ ones holding the brake shoes, and then finally a bunch of 1” ones for the brake rigging. Original pin is across the bottom. Old and new cotters on the left side.
Pretty sure EDM s were not popular 100 years ago, so it had to be a bunch of cheap apprentices making the holes. Anyway after looking at some of the original pins, I was confident it was a hot punching approach. I conjured up a punch and die set and the first run was 5/8” dia pins. Next batch is ¾” dia. Fortunately all pin sizes use the same size cotter. Die was showing a bit of drag after the 10th pin so I was thinking may have to alloy face it, or redress after every 10 pins. Then after cleaning the die, enlarging the waste hole, and applying a bit of never-seize every four or five pins, it popped out another 20 with no problem.
Success, Really happy when the press came down and there were no unexpected crunching sounds. We try to stay authentic at the museum and this was a good exercise.
These pins hold the journal box covers, next set was the ¾ ones holding the brake shoes, and then finally a bunch of 1” ones for the brake rigging. Original pin is across the bottom. Old and new cotters on the left side.