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return of the GreenWorks switch problem
Monday, June 29 2015
After hiking on a big loop that included the Farm Road and most of the Stick Trail, I was about a quarter mile south of the house down the Gullies Trail cutting pieces from a fairly large fallen oak when the switch of my GreenWorks chainsaw started acting unreliably. I banged the chainsaw in hopes of getting it to work. This was effective, but now the switch was stuck in the "on" position, and the only way to turn off the saw was to remove the battery pack. If that chainsaw had more power, it might've been a nightmare scenario, but I could actually use it like this to finish my work. It was still overheating and also turning off for that reason as I made big cuts, suggesting I still need to work on my blade sharpening technique.
I returned to the house carrying what turned out to be a 106 pound load of firewood. I was only carrying three bucked pieces, two of which weighed more than 40 pounds. Unfortunately, due to recent rains, some (though, given the inherent dryness of the wood, not much) of that weight was water.
Up in the laboratory, I took the GreenWorks chainsaw apart to see what could be done about the failed switch. I've repaired this switch once before. It's a single-pole, dual-throw (SPDT) switch which had used both throws in series to control whether or not the chain was moving. One of the throws had gone bad, so I'd jumpered around it. Today I found that now both throws were bad. The old one could never make a connection and the new one was stuck in the closed position. I took the switch out and was able to disassemble it, showing that the spring had broken on the latest-to-fail switch. The spring was still good on the other one, but something was making it so it could not close. It looked like I couldn't fix it. What to do?
I couldn't find any replacements for that particular switch online. I didn't even know what the name of that kind of switch was. So desperation, I dumped out my collection of assorted switches on the floor. And damned if there wasn't a switch very similar in size and shape to the broken one on my chainsaw! It was only a SPST switch, but I only needed one of the throws. (Does wiring switch throws in series make them last longer? It would seem that wiring them in parallel will reduce the current on the contacts, while wiring them in series would only act to make the system less reliable.) Miraculously, I found this random switch (a type that, it turns out, is called a "mini snap switch with a pin plunger actuator") fit perfectly in the little switch compartment in the chainsaw housing and even switched with a delightful click when I pulled the chainsaw's trigger (though I did have to add some electrical tape shims to make it completely reliable). I put the whole thing back together and it seemed to work perfectly.
Over at my hung-up skeletal tree project across the Farm Road, I managed to remove the last traces of that tree, which probably came as a big relief to the hickory (Mockernut Hickory?) it had been hung up in. The dismembered tree now lies in a pile of large pieces at one of my "staging areas," where I can buck it into pieces or carry it out in longer sticks. This particular staging area is about 400 feet to the west of my woodshed and it's possible for me to get to it with a handtruck.
Gretchen returned tonight about a half hour before midnight, and we stayed up talking at length about her trip. Portland is as great as ever and now supposedly the relentless vegan propaganda is poised to convert both Gilly and Alan (the people with whom she stayed) into vegans.
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