Starting the Year off With a Bang
My day began the way it usually does. A slow, begrudging realization I could no longer stay in bed. Thenceforth, the normal routine of personal hygiene, dressing, etc; finishing with grinding and brewing my daily coffee. Everything was fine- up until the coffee.
When I plugged my coffee grinder in, it exploded. Suffice it to say my normal routine stopped being normal, or routine.
Far from being the first time something I plugged in exploded, I quickly unplugged it. Having eliminated the immediate danger, I focused on determining what, exactly, had gone wrong. Didn’t take too long:
Yes, it’s a poor quality image- but it’s clear the power cable is hanging on by a thread. It came all the way off soon after, so there was no chance to get a second take.
Originally, this coffee grinder had a sort of plastic foot you could wind the cable around. That snapped off years ago. In it’s absence the cable got put under undue stress. Embrittled, the insulation broke away until two live wires were fully exposed.
I suppose I’m lucky I don’t have metal countertops. Or use the grinder near the sink. Or leave it plugged in when I’m not using it. Sometimes you just don’t know how close you are to disaster until… well, until something explodes.
Normally replacing a cable wouldn’t be much to talk about- but normality tends to end when things explode. Repairing this coffee grinder turned out to be pretty complicated. If nothing else, it’s an insight into how a cheap consumer product is built, and the compromises it embodies.
Really though, I just want a decent cup of coffee again.
Coffee Grinder Repair
Taking the grinder apart was nicely straightforward- just remove two screws. Cleaning out a decade of coffee dust and Mystery Filth was not fun. I ended up putting everything (except the motor unit) through the dishwasher.
Taking the two screws off the bottom causes the whole thing to fall apart. On the left is the motor unit, then the stainless steel main body, then the plastic bottom plug.
The two parts in the center make up the power switch. I removed the contacts so I could clean the plastic.
Instead of a proper switch, there’s this cheap assembly. Open leaf contacts aren’t great as far as switches go- they got mostly replaced with integrated units. Apparently not all of them were.
Since I can’t use the same hole the cable originally came out of (it’d just break again), I had to add my own. This is relatively easy to do, since the metal body isn’t actually connected to anything- it’s merely clamped in by the plastic parts. No need to be too accurate.
The bottom plug thing actually extends quite far into the grinder body. To avoid issues with mechanical alignment, the inside hole is much bigger.
Threading the cable through a metal hole is a recipe for disaster- the sharp edges will tear through the insulation until another short circuit explosion happens. I whipped up a little cable bushing with my 3D printer. Getting the fit just right required some trial and error.
Since I had to cut a large portion of the power cable off, I had to rewire the connections. The hot wire is soldered to the leaf switch contact, while the neutral connects to the motor.
If I didn’t tell you I’d done this, you’d never know it wasn’t done at the factory.
Finished Coffee Grinder Repair
Putting the grinder back together was much harder than taking it apart. The switch needs to be in a very exact location relative to the motor unit, so you need to carefully stack them together. It took a few tries to get this just right- that spring kept pushing everything apart. The secret is to put the spring on the base, then put the moving part of the switch on top. Otherwise it’ll get in the way and knock stuff out of alignment.
My other issue with reassembly was that the wires are not in the same location as the original design. There’s very little space inside the grinder case, so an extra inch of wire is significant. I had to push cable into the case to get enough slack to fit everything together; then while assembling it I had to pull the cable out slowly to get it out of the way.
From what I see, this process wasn’t that different to how the grinder was assembled at the factory. The only difference is that the original design lets the main body spin relative to the plastic ends. My modification necessarily locks the two together, so the text printed on the body is noticeably off center. But it’s so worn off, you can barely read it- so who cares?
If you don’t know how this grinder is supposed to look, you wouldn’t think it was repaired. That’s what I call a success.
A reward well earned!
My only complaint is the power switch is noticeably stiffer. Perhaps the parts aren’t properly aligned. Thus far it works, so let’s call it a success.
Anything that doesn’t explode unintentionally ought to be called a success.
Finishing Up
Repairing things is always a bit of a gamble. You don’t always have the tools, knowledge, or information to do the job properly. Occasionally the repair ends up costing more than a replacement. There’s always the risk that the repair makes things worse.
Ironically, it’s the cheap disposable products that tend to be the easiest, most cost effective things to repair. A quick look tells me that a new grinder of the same model currently costs about 30USD- not including shipping or transportation. Thirty bucks might not seem like a lot, but it’s about half a day’s wages of a low income worker. Any repair is going to be pretty cost effective here.
Compare that to your smartphone which could be anywhere from two days of work to to a whole month or more. Sounds like a more worthy repair job, doesn’t it? But, given the specialized skills, equipment, and time required, anything but the simplest phone repair is far less appealing. Assuming you’re even allowed to repair it, which is it’s own issue.
Speaking of those skills, equipment, and time, this repair required little. You need basic tools (screwdriver, wire cutter, soldering iron, drill+bit), basic electrical skills, and an hour. Other than the soldering iron (which isn’t strictly necessary), I think most people have those things- or know someone who does. I used a 3D printer to make the bushing, but those are standard parts. Finding or salvaging one shouldn’t be too hard.
While my intention was, and is, to show projects that are wholly my own, it occurs to me that showing some of the repair/modification work I do might be interesting. I’ve done two (this, and replacing the floppy drive in my logic analyzer) so far, both of which were immediately satisfying. If nothing else, it’s acceptable filler material when I’m stuck waiting on another project.
2023 is starting off at a sedate pace. Sure, there’s all kinds of exciting, terrifying things happening both in the US and around the world. It just hasn’t come for me. Yet.
While we’re all waiting for the bottom to fall out of society, I’ll still be here, working on things as I’m able. Now, if you’ll excuse me, I’d like to assuage my existential anxiety with a freshly ground cup of coffee.
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