After getting the roller chain I measured several samples. I use calipers to get the thickness of the master clips, and pin gauges to measure the holes. Then I went back to my pin design and updated the dimensions to match. I took several samples of each part to look for variation in manufacturing. It was also time to add some tolerances to my print.
I went back and forth with the supplier in China about the pins. I needed to balance the production costs with the prototyping costs. I want the production pins to be as inexpensive as possible, but I also want to be able to order a small quantity up front to test. If I could commit to high quantities now they would send me samples, but I don't have that kind of money to invest up front. I wanted the prototypes to be the same parts I would use for production so I won't have to order another round of samples.
Another issue was I wanted to make pins that would work for both the mild steel chain as well as stainless steel. The dimensions were slightly different and that made it a little tricky to balance.
After several emails back and forth I was able to come up with a design that was cost effective, and that I could stomach the prototyping cost. Again shipping was a pain and DHL cost me $150. But I figured that by now I had put enough time and money in that I had to see this thing through.
The pins arrived and either due to luck or a lot of planning and testing they worked perfectly. The master clips snap on with a satisfying click seem really strong. Next step is to make a better silicone mold and turn these parts into tank tracks.
The pin for ANSI 35 and ANSI 40 roller chain. 3" and 4" in length
Close up of the snap ring groove.
Test fitting the parts on the pin. Everything pits perfectly. (Huge sigh of relief)
Close up of the master clips for mild steel.
Close of up the stainless steel master clips
Mock of of what the track will look like.