Saturday, September 4, 2010

Lawnmower Engineering

I use a reel lawn mower. Besides being cheap on gas (free) and maintenance (free) and fumes (none) and storage (little required) and self-fertilizing (kinda), I just like it. It's a little workout, but I have a small yard and it's not bad, especially when it's nice outside. That being said, my poor mower had a wobbly wheel for a long time. I tried to tighten the bolt up, but I couldn't get the wheel off to tighten the dang thing -- the wheel assembly is riveted together and bolted to the mower, so the access to the bolt is blocked by the wheel itself.

I dealt with the lemons life had handed me for awhile, but a few weeks ago the wheel itself just fell off. At that point, I decided I needed to do something to salvage my engineering pride. What to do? Drill a hole in the wheel, of course.

Actually, I drilled a hole in the wheel with a spade bit, but then I had to carve out a little more with my jigsaw to fit my socket driver in the hole. A few minutes later, we were back in business -- maintenance cost still $0. I'm planning on sharpening the blade myself as well, and I'll definitely post on that!

As an aside, what you DON'T want to do is cut into the actual rim part of the wheel. Although the inside does carry some compressive stress, the outside carries the majority of the stress (see: hoop stress). If you bite into the rim, you'll need to fix it with a hard plastic or a piece of wood to keep the wheel from bending (and wobbling).

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