LED Flashlight Switch Repair Failure

This didn’t work out, but it came close. Eventually I’ll figure out what material can replace the boot, at which point I’ll need to remember these steps…

That LED flashlight + laser pointer has a rubber boot over the push-on / push-off switch stem that makes it sorta-kinda waterproof. Although I wouldn’t trust it in more than a sprinkle, it’s my pocket flashlight and tends not to get soaked very often.

Anyhow, the rubber boot wore through:

Broken switch boot
Broken switch boot

Taking it apart, now that I know how, was easy enough:

Switch button parts
Switch button parts

Note that the mushroom part goes on the outside, which means the stem will vanish if the boot rips apart.

I planned to mold a boot from acrylic caulk, so I wrapped narrow strips of electrical tape to match the stem to the mushroom head, then wrapped a bit around that to make the final boot fit loosely:

Wrapped switch stem
Wrapped switch stem

A thin layer of oil served as mold release, over which I smoothed a blob of caulk. This looks awful, but the majority of the blob at the bottom will get trimmed off:

Switch stem covered with acrylic caulk
Switch stem covered with acrylic caulk

Unfortunately, the cured caulk turned out to be remarkably fragile. Each individual blob felt tough, but it’s really not designed to form thin membranes; I got about what I expected.

Pourable silicone rubber seems like the right hammer for the job: make an outer mold to surround this thing (or a 3D printed replica) and pour it on. I must get some of that, one of these days.

So I put the flashlight back together with the mushroom on the inside to keep the stem in place… and I generally avoid getting more than knee-deep in liquids, so not having a good seal won’t matter too much.

8 thoughts on “LED Flashlight Switch Repair Failure

  1. You might be able to make do with thin plastic, softening it with a heat gun and forming it to shape. It would probably yield a stiffer button, and I don’t know how many flexures it would survive. Or you could try impregnating some cloth with caulk to yield a composite that should have plenty of flex and give some semblance of water resistance.

    1. It must be very flexy, because it’s captured at the bottom between the plastic hoodicky and the flashlight body. The button travels 3 mm from full-out to flush with the body.

      I like the cloth + goop idea; maybe there’s a scrap of oilcloth or some such in the rag bag that would be a good start…

  2. The last time I wore out the button-cover on a flashlight I called up the mfr and they sent me a dozen or so for free. Of course, I doubt yours *has* a mfr, or that they speak English… :)

    If you still have all the pieces of the old cover, I would use it as a master for a mold and cast some silicone, I think.

    1. I doubt yours *has* a mfr

      It is as devoid of maker’s marks as the fresh-blown snow: strictly from generic.

      If you still have all the pieces of the old cover

      Now, do you think I’d throw something like that out? Really? [grin]

    2. Not exactly what on topic, but I have a made in China 30 led flashlight that worked very nice until the push/push off switch broke. I noticed you have a similar switch. Any ideas where I can buy just the switch? Appreciate anybody’s ideas.

    1. Never heard of the stuff before…

      Rummaging through their website & user comments, it looks to be not bendy enough. It has trouble with impact loads and doesn’t have good fatigue life, which suggests deep flexing would kill it in short order. It seems to be intended for blob-style repairs / construction / adhesion, rather than thin films and flexible joints.

      And it’s really spendy, comes in tiny single-use quantities, and has a painfully short shelf life. If it were stocked at the local Big Box, I’d give it a try…

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