This thread is for anyone working on personal projects to share their progress, and hold themselves somewhat accountable to a group of peers.
Post your project, your progress from last week, and what you hope to accomplish this week.
If you want to be pinged with a reminder asking about your project, let me know, and I'll harass you each week until you cancel the service.
Well, it seems this thread is still not doing too badly relative to the other regular threads, so let's stay on a weekly pace.
Jump in the discussion.
No email address required.
Notes -
It depends really heavily on the type of watch. Cheap watches usually don't even need kits, just a thin flathead jeweler's screwdriver or spadger to get the back plate off, or maybe a single weird screwdriver bit. Higher-end watches can be trickier: the most annoying tend to use either a threaded backplate that can require really annoying tools. But if you're only doing it once every few years, there are some cheap kits (not endorsed) that will handle almost all common watch types, albeit not very conveniently. If you know you have a screw-in caseback, getting a proper tool for that (with a handle and everything!) is a better bet than buying a kit.
For battery size, ideally look up the manual. Otherwise, just take it apart, check it, and order it. The size will be printed somewhere for almost all batteries, or you can just use a set of calipers to measure. The most common size is 1216 (12.5mmx1.6mm), but there's a lot of size charts, and you can get plastic digital calipers from Harbor Freight or the like for dirt cheap. Don't try to memorize the numbers, there's charts available. Do get the cheap plastic calipers; watch batteries have enough internal resistance and limited enough ampacity you're not going to light the house on fire, but it's still a stupid way to warp calipers.
Do keep to a compatible voltage: coin cells come in 1.5V, 3v, and 3.7v (nominal) voltages; using a lower voltage than the original usually won't work, while higher voltages may damage the electronics. Almost all modern watches use 1.5v silver-oxides (SR or SG prefix). While that's compatible with alkaline low-voltage (LR/AG prefix), zinc (PR/Z prefix) and and mercury (MR, no longer manufactured), silver-oxides are cheap and generally ideal for watches, especially mechanical watches. Lithium (CR/BR prefix), Lithium rechargable (LiR), and titanium (CTL prefix) are all higher voltage, and while lithium-titanium (MT) are technically the right nominal voltage they're basically never useful in watches due to high self-discharge and low total capacity. Again, battery type should be in the manual, and printed on the top of the battery.
For mechanical watches, the most common designs only use the crown to hold the balance wheel in place (or disengage it). There are designs where it will disable the motor or disengage the battery entirely, though. It might save some power, but I wouldn't swear on it being a big gain, since self-discharge makes up a pretty sizable part of watch battery life anyway. For digital watches, it will never disable the main circuit, because otherwise you can't set the time.
Big cautions I'll give:
Thanks so much! Somehow, you always seem to deliver on TheMotte! A couple follow-up questions:
Years back, I totally ruined a cheap watch trying to pry off the back plate to replace the battery, just using whatever screwdriver I had sitting around. IIRC, I just bent stuff (I think the back plate, itself) and it was a mess. I probably tried to block out some of the experience from my mind, but that's part of why I wanted to ask and actually prepare myself with a modicum of knowledge before considering giving it another go. Any suggestions to help with this? Just use a super thin screwdriver and carefully work it around the sides of any opening rather than prying it all in one spot? Anything else? For popping it back on, do I just line it up and squeeze, or is there a better technique?
The watch I just had the battery replaced in doesn't look like a pop off back plate. It has six evenly-spaced little square notches right on the circumference. I assume this means that it's a screw-in that should work with a tool like what you linked from Harbor Freight? Or are there variants of this tool that I'll need to match to the particular model?
Really cheap snap backs can be especially annoying to pull, but usually the concern in those cases is about scratches or cutting/stabbing yourself. The backs are really not supposed to take that much force to pop off to start with; if it could be bent with just a jeweler's screwdriver that sounds more like a manufacturing problem.
You can get specialty tools for it ("bench knife" or "watch case knife" for the traditionalists, but I don't recommend them; pry tools are safer and even vice-style ones exist if you're worried), but I've usually been able to work fine with normal electronics repair kit screwdrivers.
You want as wide of a flathead tip as you can get, while still fitting under the notch (or pry tool, or whatever). If it's really tight, using a plastic spadger or guitar pick around the edges while prying up from the notch can help a lot, but you don't want to try to dig anywhere closer to the center of the watch than that notch, and trying to slide metal around the edge will scratch stuff to hell.
There are special presses for pressing back on snapbacks (or you can even use button presses), but I've never found them particularly useful myself. Grab a hardcover book or softwood lumber, put the watch face-down on a clean and slip-resistant surface such as a mousepad. Start by pressing evenly from the top, and then give a little side to side pressure. It doesn't take that rigid of a shape and shouldn't take much force; I've seen people do it with a plastic level before.
Square notches along the back would point toward a twist-off threaded back, so the HF case opener tool should be the right one. There are different sizes and shapes of notch for threaded watch backs (and different configurations for even- versus odd- numbered notches), but that HF standard tool comes with a pretty wide variety that covers basically everything I've seen. Like above, these are better used with the face of the watch being pressed down into a clean slip-resistant surface, or you can get (or make with a few wood pieces) jigs to hold them in place so the watch doesn't spin while you're trying to unscrew the backplate. There are other variants of the tool if you know the notch type and count (and some weirder things like stress-ball tools that work great for cross-threaded backs), but most of them are worse to use in practice, so I don't really recommend.
Awesome! Thanks so much!
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link
More options
Context Copy link