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I spent a while learning about sewing machine timing and repair a couple of years ago after buying a very nice vintage Elna at a thrift store for $20. Turns out that the way most of the timing is set is based on the height of the needle when the shuttle mechanism underneath is in a particular place. You loosen the set screw on the collar that connects the upper and lower mechanisms, set the needle to the height of a gauge block from the manufacturer and then rotate the lower mechanism until something lines up, then tighten the set screw. Those blocks are almost all long gone for anything that's still mechanical, and the modern machines are all electronically timed with stepper motors in the top and bottom. Fascinating stuff if you dig into it.

That's a good use for 3D printing, assuming someone knows and can publish the appropriate measurements for the gauge block.

The problem is that no one (myself included) wants to do the work for the measurement. You need to retime the machine in front of you, and once you do, you don't really have any need to make up the gauge... Also, this is probably going to need to be more accurate than I understand 3D printing to generally be. I probably don't need to use my set of Starrett Grade A gauge blocks, but I probably want more accurate than your average ruler.

I have a desktop, sub-$800 printer and can print to 0.1 mm thickness without extraordinary measures and using inexpensive calipers, you can measure down to below 0.01 mm. (Thereby getting potentially more than native precision by repeated attempts.)

Thermal expansion of the plastics being different than the machine is a small issue, which could be solved by measuring, calibrating, and adjusting all at a given temperature.

Your point about limited motivation is spot-on, of course.

That makes me want to go inside my older machine and mark the current positions, say with a sharpy or dye. Mine had the main plastic timing pulley break in half and is un-obtainium. So I epoxied the pieces together, while drilling holes and embedding steel wire reinforcement. Works like a champ, though I go the feeling it was built with planned obsolescence, as the rest of it was built like a tank.

Sometimes such a plastic parts sole function is to break to avoid major damage to the rest of the machine. If you make it stronger and the same conditions occur something else might break or bend that is a lot harder to replace or repair.

You'll see the same in farming equipment, there are usually one or two sacrificial bolts in there that will be happy to snap if the tool gets wedged, rather than that the tool snaps.

I get the sacrificial analogy, but in fact, the larger problem is IF the cam does fail, will it allow interference that will lock up at speed and potentially destroy the highly powered but delicate mechanisms, as you find destroys engine valvetrains, mainframe printers, among others. And this is what it did; when it failed everything locked, but luckily nothing was destroyed because otherwise built like a tank. The alternate explanation is that it is simply a very complicated cam device with many extreme contours, expensive to fabricate from anything but plastic injection, with high force followers that cause it to fail over time, leading to a trip to the sewing machine repairman. edit: I called it a pulley, but it in fact was a complicated cam.

I took me a long time to figure out that under my magnetically attached spool holder/shuttle junk had built up allowing it to jump off the magnet, but only at high rpm, breaking the needle. BTW, when I went to school, you had to take Home Econ to graduate, and I learned to use sewing machines, utilizing sewing patterns and common tools like tracing paper, with a final project, as well as demonstrate many hand stitches. I wished my children would have had this opportunity.

Buy a cheap second hand (old!) sewing machine and you can give your kids that opportunity at home.

I've been on a project for a couple of months where I sort of re-play the whole industrial revolution and the electronics age one device at the time. The local goodwill store has a good customer in me.

Oh, they learned some of it (now adults), just not at the level I was exposed to - and that is it really, always competing priorities.

The prices of modern appliances have come down due to really intricate miniaturization of many components, which enables larger scale manufacturing and cheaper supply chains.

Because of the prices being low, it's not really worth it to repair consumer goods anymore. And if it's worth it in some cases (iPhone), it can only be done by a specialist due to the extreme miniaturization.

Sewing machines are hard to miniaturize. I'll give you that the newer crop are cheaper, but they will also only last a fraction of the time, that decrease in price has also come at the expense of quality.

Not that that matters as much any more, people tend to buy clothing rather than make clothing, this particular machine was a wedding gift from my grandfather (a tailor) to my mother and it was meant to last a lifetime, so that the family would have clothes to wear. Making clothing was so common nobody thought anything special of the skill involved, everybody could do it!

But if you tried to seriously keep a family of four clothed today based on fabric bought and a modern day sewing machine you'd be buying new sewing machines ever few years.

Modern sewing machines are cheaper because the intricately machined cams and drive mechanisms that connected the upper mechanism that moves the needle to the lower mechanism that moves the bobbin are no longer used. They're replaced by a pair of stepper motors that are driven by a microcontroller. Instead of having collars and set screws to adjust timing, it's all solidly built and ruined the minute the stepper motor slips or a tiny plastic part breaks and something no longer actuates. They're unrepairable because you'd have to get the actual OEM somewhere in China to release the source code and put a jtag pinout on their boards rather than getting the chips loaded at the factory where the main board is made. That's the difference. Same reason that cam machines have been replaced with vertical machining centers -- CNC is just waaaay cheaper.

Conversely, back in the days if you had any kind of a significant IBM mainframe installation you had an IBM technician if not a team of them on an on-site contract to keep the thing running. The idea of an unattended data center, filled with computers that can run reliably for years untouched, was unthinkable then.

When I was still working with mainframes we used the IBM diagnostics on a Sperry machine (it could emulate the IBM instruction set), they were so much better than the Sperry ones that hardware faults would be isolated much quicker.

One of the best hackers I ever worked with (a guy called Paul Poelenije, unfortunately deceased) had figured out how to load the microcode store and to pull this trick, I'm pretty sure that both IBM and Sperry would have been horrified at it in equal measures. For an encore, he wrote a completely new filesystem in assembler, and used it in production for the bank we both worked for. How he got away with that I'll never know but somehow he managed to get the blessing for his pet projects from the manager of the systems programming division to who I'm going to be eternally indebted because he had a big say in me coming to work for the IT department instead of the mailroom.

Those Sperry's were massive machines, the two mainframes (primary and backup, or production and test depending on what we were up to) + peripherals took up all of one floor of a very large office building and there were always at least several people on duty to keep them running. This was mid 1980's and punch cards were still being used with some regularity.

+1 for even knowing the word "Sperry."

I named my dog Sperry simply because nobody in my company had ever heard of it, and I didn't want the name to die.

I've discovered that modern appliances are repairable, thanks to the internet. There are people that have been making a business based on supplying parts (for example for made-in-China GE dishwashers) and videos on how to install them.

I think it's more accurate to say that first world labor costs are such that it's not usually worth it to pay someone to fix your devices these days, but it's becoming easier to DIY.

I also fixed an old laptop based on mail order parts and a youtube video. It really gave me a sense of accomplishment because I turned to programming computers very young partly out of ineptness with mechanical devices.

Yeah, the Internet is a godsend to people who repair their own appliances. For the most part you just have to figure out what's wrong (most appliances are pretty simple, so this isn't very hard), then look at the part for a model number and punch it into Google. Failing that you can enter the model number of the appliance and often get a parts list. The part you get usually won't be an exact match, but it should work, although you may have to fabricobble a bracket if the new part isn't the same size/shape or has mounting holes in a different location. This is pretty rare though, usually it's just bolting the part on.

This is also when you discover that even though Frigidare may sell dozens or hundreds of different fridge models at wildly different price points over the years, most of them use basically the same innards.

The key for someone like me is a site with videos for every little part for the exact model of appliance. And troubleshooting information, and possible causes of a symptom ranked by customer experience %.

There have always been DIYers, but I cannot do much of anything with just a service manual or parts list.