(ET) The key to snowthrowing

[Larry Chace <RLC1 etnainstruments com>]

Back in December I commented about losing the key that locked the 
snowthrower drive sprocket to the motor shaft.  As a result, I tried 
several techniques to fix that problem.  Until now, there hasn't been 
enough snow here to warrant using the snowthrower, so the 
effectiveness of those fixes has remained unknown.  (The E15 with 
plow was able to clear the driveway.)

Here are the fixes:

1. Install a new setscrew.  (The old one looked OK, but why not use a new 
one?)
2. Install a new key (3/16" by 1").
3. Install a second setscrew in the hole at 90 degrees from the first one.
4. Apply Lock-tite to the setscrews and key.

The sprocket hub appears to be too small in diameter to allow for an 
additional setscrew that would lock the first one.  I tried to 
compensate for that by grinding a small indentation in the face of 
the key where the setscrew touches it.  The idea was that the 
setscrew would then lock the key into place when tightened.

"Tightened" is probably a crucial consideration, as I had been using 
a wimpy little 1/8" Allen wrench to tighten the setscrews.  That was 
difficult, with the Allen wrench on the bottom side of the hub, the 
only way that there was clearance for the wrench, and doing the job 
with a flashlight and mirror.  Instead of the Allen wrench, this time 
I used a 1/8" hex bit with a 1/4" hex driver, which gave a lot more 
"purchase" on the setscrew.

At any rate, the snowthrower now seems to work correctly.  The 
sprocket has stayed in place.  Of course, I don't know which fix (or 
fixes) really did the job.

Larry Chace, Ithaca, NY  I-5 (snowthrower) and E15 (plow)