Philosophy and mower repair

I bought a new lawn mower in 1995. It is a simple self-propelled walk-behind mower with a mulching kit. Outside of oil changes and a few new spark plugs, it has been relatively maintenance free. I’ve lost a couple of bolts from the handle which have quick release nuts so that the handle can be easily folded and I have replace the rear driver wheels twice. I’ve done all of the maintenance on the machine myself so far. Our lawn is nearly a half acre, so the mower gets a workout each week. Last week I was in the midst of mowing the lawn when one of the rear wheels fell off. When I inspected it, I found that the axle bolt, a specialized bolt with a large shaft at one end to fit into the bearing and a smaller threaded portion, had broken. The most likely cause for the breakdown was that the bold had become loose and I hadn’t noticed and the extra stress and leverage caused it to break.

Needless to say, I didn’t finish mowing the lawn that night.

A broken bolt stuck in a threaded hole is the topic of a whole chapter in Robert Pirsig’s novel, “Zen and the Art of Motorcycle Maintenance.” I don’t think I quite follow the practices described in the book, but then again, the book is a novel, not a religion textbook, even if it has a philosophical bent. For my lawn mower, the first step was to remove the bolt cover on the wheel and inspect the damage. Fortunately the plastic drive gear was not damaged, so all that needed to be replaced was the bolt. The bolt was a special item that I would have to obtain from the dealer, so I was done mowing for the evening.

I went into the garage to get a center punch, a drill and bit, and an easy out to remove the piece of the bolt that was still in the mower. As is sometimes the case with hardened steel, the bolt was a bit difficult to drill and I was using a hand drill, so the hole wasn’t quite straight. Then, instead of going back into the garage for a handle for the easy out, I put a crescent wrench on it. The wrench was much too big, but I was getting tired and wanted to get the job done. If you’ve ever done this job, you can imagine what happened next. I broke off the easy out in the bolt. Now I had a real mess and I retired for the night.

On Friday, I went to the store and got a new bolt to replace the broken one. With the extra hard steel of the broken easy out in the bolt, I tried to remove it with a chisel and a free other tools, but ended up drilling it out with a larger bit. The end result was that the threads were messed up. I tried cutting new threads with a tap, but my drilling had enlarged the hole and I didn’t have enough threads in the top of the hole to hold the bolt.

Saturday was a very busy day for me and I didn’t have time to work on the mower, but I did have time to go to the auto parts store and obtain a heli-coil for new threads. The system is really ingenious. You tap the hole with a bigger tap and then use a special tool to screw in a coil of stainless steel threads that stick out enough to make threads of the original size. The problem is that you can’t just buy one coil. They sell them by the dozen. And each size of coil has its own special tool for inserting, based on the size of the coil. I needed 8mm course thread metric threads, so I had to buy an installation kit, which also included the tap for the project. At that point I was about $40 into my $100 lawn mower.

I didn’t have time to work on the project on Sunday, but the grass didn’t take a vacation from growing while I was getting my lawn mower fixed.

Finally, yesterday morning, I carefully applied lubrication to the tap, cut the new threads in the mower housing, inserted the heli-coil, and reinstalled the wheel. Victory! After four days of having my mower broken down, I was able to finish mowing my lawn. Of course by that time, the section that I had previously mowed had grown so instead of having a patch in the middle of the back yard that was longer than the rest, when I finished mowing there was a patch of the same size in the same place that was shorter than the rest. I’ll let that go until later this week when I’ll have to mow the whole lawn.

I have a few mechanical skills, having grown up around a shop with good tools and mechanics who knew how to use them. And I’ve collected a fair amount of tools over the course of my life. But I don’t make my living working with mechanical repairs, so many repairs which are simple for a professional shop, like fixing my mower, take me two or three times as long as they would take a competent mechanic. I have to force myself to be patient and to do the job the right way, even if it takes me longer. Had I slowed down with the broken bolt, I suspect that I could have turned it out of the hole without messing up the threads in the first place, saving both time and money.

There is actually quite a bit of philosophy involved in basic mechanical repairs. Pirsig got that right. Thinking carefully and taking your time is a necessary skill for making repairs. It seems to be a lesson that doesn’t always stick with me. I think I can get it fixed and I plunge right in and make mistakes. Like most of the rest of my life, I learn a lot by admitting my mistakes and then cleaning up whatever mess is left behind.

At any rate it appears that the lawn mower is good for one more season, which is a good thing because I need it to earn back the money I just invested in it.

Copyright (c) 2020 by Ted E. Huffman. I wrote this. If you would like to share it, please direct your friends to my web site. If you'd like permission to copy, please send me an email. Thanks!