Anatomy of a failed TK-11 switch.

Recently a TK-11 I gave as a gift suffered a failed switch. Sometimes it would turn on and sometimes it would take multiple clicks. 4Sevens immediately took care of the issue and very quickly sent me a replacement. I took the opportunity to take apart the old failed switch. Here are a few pictures of what I found.




As you can see there is a tiny pin (black) that holds the small spring in the center of the base of the switch. This pin has broken off and lodged within the center of the small spring. Once the pin is broken off the contact ring is free to move from side to side and therefore not make contact with the proper pieces.
I can see no easy solution to this weakness. I've save all the pieces and may try to re-assemble it. Maybe as momentary only.

Thumbs up 4sevens for your awesome warranty.

oh my.... the entire function of the light depends on that tiny plastic black rod? :shakehead This should be addressed to Fenix for a switch update.

thanks fore the info, i was goingto get one.

petersmith6 said:

thanks fore the info, i was goingto get one.

Click to expand...

switches are a replaceble item. they do wear out in normal use and sometimes can be defective..in any brand light. fenix does sell the
switches as a spare part..however 4sevens and the OP probably
felt it failed in too short a time and simply covered it under warranty.

dont junk the car because of a flat tire. the TK-11 is still a nice light
and companies do analyze warranty returns to determine when and
where updates are needed. maybe the switch needs a redesign, maybe not..
havent heard about any premature failures of this type, so it's probably quite
rare. the op probably just got an unlucky one...and got it easily fixed.
nothing wrong with that.

Little dab of solder might allow the switch to function again. Screw one coil of the spring into the center hole of that tab, and a drop of solder will keep it from moving around.

Thank's for the the deconstruction and photos.

The question would be once assembled how easy is it to subject the pin to lateral forces that would cause it to break. Can pushing the switch on an angle break it?

From this pic it is not clear that the the pin was actually affixed to the base rather than just inserted in the hole, but I presume you've assertained it was broken off from the base. It seems to me that a slight redesign using a metal pin could be done where the pin is just inserted in to the hole for positioning could be done, it could even be inserted from the bottom during assembly with a collar to prevent it from being pulled through. Or it could all be manufactured as 1 piece, that would be the best. I've looked at a lot of switches and that one actually does not look too bad from the pics, but I can't really say without a first hand inspection.

What if they made the bottom part out of metal and then coated the metal with a layer of non-conductive but hard wearing material?

Here is a better shot of where the little post broke off.


I would still highly recommend this light. The service and support are excellent.

Manufacturing flaws - liked a flawed plastic casting - create incipient failures which usually shake out in early use. It's why you want to "prove" your equipment before you risk a lot on it. After that, they should be pretty good unless they have a real design flaw which I doubt is so for Fenix.

True Fenix statistics may be just fine, and you just got a fluke. We don't know. Statistics are hard to acquire because manufacturers don't like to release data which says their failure rates are not zero although that is true for everyone.

Disclaimer: I'm a fan of spring loaded twistys, which usually have a metal mount for the spring and no moving parts...

I think I'd try drilling a small hole through the base of the switch (where the plastic pin broke off) and inserting an appropriately-sized screw from the underside. That should serve the function of holding the spring in place and (depending on the thickness of the plastic base) should be more resistant to any possible lateral forces. Of course, I hate to throw anything away (even if my time in tinkering with it amounts to several times the worth of the item).

sylathnie said:

As you can see there is a tiny pin (black) that holds the small spring in the center of the base of the switch. This pin has broken off and lodged within the center of the small spring. Once the pin is broken off the contact ring is free to move from side to side and therefore not make contact with the proper pieces.
I can see no easy solution to this weakness. I've save all the pieces and may try to re-assemble it. Maybe as momentary only.

Click to expand...

The problem has persisted from the initial T-series release. Check out the "torture" testing thread I did a while back.

Short of a redesign or a change in materials, the problem is not likely to go away. Then again, it's not really a *huge* problem, since the light is still operational and 4sevens will take care of things.

Simple bulletproof fix would be the following at least IMO.

Solder the base of the spring to the round ring on the center contact. Superglue the entire center contact piece to the plastic base. Lube all parts of the switch. Should never have another problem.

Surefire's old switches have an identical mechanism with slightly different contacts, the pin is metal.

That's why I REALLY like Surefire's twisty.

Looks like I will avoid this problem with my P1D.:twothumbs