The button to always work when pressed (so that when you feel it click, the light always goes on)
The button to be reasonably hard to press
I modded my FW3C and FW3T the same way (but my FW3C didn't have a retaining ring--maybe that got added later): I removed the nubbin and used a keyboard o-ring (tried two different thicknesses: 0.4mm and 0.2mm).
The FW3T (with the retaining ring) behaves pretty well now: the click is positive and the light comes on.
The FW3C on the other hand: the click feels the same, but getting past the "click" isn't always enough to get it to turn on. Instead, you have to "bottom out" the button firmly past the click. If you don't, the light doesn't turn on.
I really want to like this light. I just need it to work. The original button was so hair triggered it would turn on in my pocket constantly.
hmm… My o-rings are 1.82mm thick and there is no slop / pre travel to the switch.
There is nothing that jumps out at me in these photos other than the metal ‘popper’ switch might look slightly different than mine (steeper sides?). Anyway if these orings work in your other samples then maybe the best advice I have to begin troubleshooting is swapping the switch/spring/pcb assemlblies between your lights and see if the behavior follows the pcb or the host.
I have done this and it is another way to tune the activation pressure and feel of the switch. The dang little nubbin is hard to work with though.
Basically any way that you apply force closer to the center, the required force will be reduced. Secondary effects include the durometer / shape of the interface material.
Thinking out loud… to surpass mucking around with the nubbin - fill the nubbin space with a suitable size dollop of glue or solder (after it has cooled, of course)….?
Only thing i had done different with my original fw3a (it had a retaining ring) was the o-ring i used has a little larger diameter, and it just so happened to be the same exact size as the “hollow” cupped section of the rubber tab that holds the nubbin. When i used my o-ring of that size, i did not use the nubbin.
What i ahd found while trying to fix a fw21 pro tail cap-
The more close to the center of the metal popper your oring/space/nubbin is - the easier the activation of the switch it. The further away from the center of the popper the oring / spacer is the more difficult the activation is, obviosuly.
Meaning - the nubbin is directly in the middle of the metal popper, so it activate very easy.
Using an oring that fills out the whole “dished” section of the rubber does two things -
automatically centers itself around the metal popper
is the largest and furthest it can be from the middle of the metal popper, ultimately making it need the most force to turn on.
it also esnures reliable button activation, as it does not have the ability to “slide” from side to side in the “dish” on the rubber tab piece.
I assume one reason your experiencing unreliable activation with your current oring is becaue it has room (albeit, only a little, but a little matters in such tolerances) to move from side to side in the “dished” section of the rubber tab.
My oring that filled out the dished section completely made for very reliable activation.
I will measure my orings once i find them and report back. It is more about the OD, outside diamter. I bought about 25 10 packs between 10 different hardware stores to find ones that fit right. I think they ended up coming from a multi pack.
As I specified from the beginning, –008 industry size is an exact fit to the rubber boots cavity. It is a 1.8mm thickness which leaves non room or slop in any direction and minimally preloads the popper. I don’t know if anyone has had issues when using this size.
A click is a click is a click. By that I mean if it’s clicking then it should be switching. So I suspect that you are looking at a contact issue elsewhere. However, I used an o-ring that I just happen to have hanging around so I didn’t measure it but it fit with just a little bit of play and it definitely sat up proud of the rubber piece that it’s sitting in. The idea of moving the tail cap or switch to different lights should prove everything.
Verdict: the problem follows the PCB. I swapped the PCB from the FW3T to the FW3C and the problem followed the PCB to the FW3T. I did not swap the retaining ring (per the above, only the FW3T had a retaining ring: I kept that retaining ring in the FW3T after the swap).
So, what can I do?
Here are some more photos showing which PCB was in which torch originally (before the swap).
Remove the poppers and inspect under them. To me it seems like the troubled one isn’t touching the center pad reliably. You could put a tiny solder blob on the center pcb pad and likely clear this up. Make sure the popper is taped on nice and centered and there is no debris or flux splatter on any of the contacts or popper. Wiping down with a cotton swab and ipa then deoxit if you have any could help too.
So when is a click not a click? When the clicker is dirty or burned or otherwise fudged up. When you open it please take some good pictures with good lighting before you start cleaning.