Fixing a Broken Main Spring

[donniej]

I have a motor with a spring that broke near the shaft end, the spring has pear-shaped holes. I always enjoy a challenge and decided to try to repair it, since the broken area was only the last ~2", 99% of the spring would be in tact. After removing and cleaning the spring, it was easy to cut the damaged end with a (hefty) pair of snips. To form the hole I decided to use two drill bits, one for the larger end and a smaller one for the small end. Drilling the hole caused the steel to split, as it's too thin and hard. Heating the last 2" cherry red with a plumbers torch and allowing it to air cool was sufficient to anneal it. Cutting it was easier this time and drilling it worked fine. The rest of the hole was formed with a die grinder, but a Dremel would also work fine. Two pairs of large needle nose pliers were used to form the tight curve to go around the shaft.

Hopefully some adventurous individual who's on a budget will find this helpful.

[EarlH]

You have to heat a few inches of the spring up red hot and let it cool off and then you can drill your holes. You need to draw the temper out of the spring also, so it will bend around the shaft and not unhook and refuse to hook back up when the motor runs down. If you don't draw the temper out of the thing, it will split as you've figured out.

I usually drill a larger hole and then a smaller one and then file it out to get rid of burrs et. I've done that with quite a few springs over the years and they haven't given me any trouble since then. After it's done, I usually wind it nearly all the way up, and leave it set for a few days so the spring will stay tight on the inside around the shaft.

Back when I had no way of getting springs I used to have a guy rivet them back together if they broke in the middle pretty much the same way. Ralph would do it for $1.00 and give me a bottle of pop for change! Those motors would sometimes make a little noise as they unwound, but at least they worked and the people I fixed them for didn't seem to mind. The 70's are getting to be a long time ago. Haha!