Fenix LD12 stuck tailcap

[jcvjcvjcvjcv]

I have a LD12... bought new, greased the threads and O-rings and regularly took both caps off. However, all of a sudden I can't take the rear cap off.

So far I have tried;
*Rubber bands over body and rear cap for more grip... but it's not budging... my hands are delaminating, the rubber bands are fusing into each other... but the cap stays on.
*Freezing body + rear cap, then dipping the cap in hot water ... plus the rubber bands again.

Does anyone have an idea why it's this stuck?

To be clear; the front can be easily screwed off, the batttery didn't leak. There is not even any major 'paint' damage on the outside.

The light works just fine this way... but it still bugs me.

 

[Labrador72]

Which version of the LD12 do you have?
In the latest one (2017), I think the body and the tailcap are just one piece.

 

[Labrador72]

I just checked my Fenix LD12 2017 version: it can only be unscrewed at the head. I also checked a couple of reviews on Youtube, just to make sure it wasn't my tailcap that was stuck.

If you have the same model, then you have nothing to worry about - just a part less to lube actually!

 

[aznsx]

I have a LD12... bought new, greased the threads and O-rings and regularly took both caps off. However, all of a sudden I can't take the rear cap off.

Clearly yours is not a model which is designed so the tail cap cannot be removed, as you stated you have historically done exactly that repeatedly.

However, I don't have any great ideas. The only other thing I can think of to consider is carefully using a bit of a good penetrating oil like (for example) Kroil such that it would creep into the threads, however I hesitate to suggest that because it could potentially get into something that could be degraded by that (switch, rubber actuator boot, etc.), and if it's not a critical need to get it off it might not be worth that risk. I've used Kroil a lot, but am not sure what materials it might attack / possibly degrade.

Many who routinely open lights for purposes of modifications (which I don't do) which are not intended to be opened use various "strap wrench" tools, and use of those might multiply the amount of force you have available without damaging the surfaces, and perhaps they could recommend such products.

 

[jcvjcvjcvjcv]

What part of "regularly took both caps off" was written in French???

I added ~10 layers of insulating tape (the good stuff) to both body and rear cap and using two pipe wrenches it came loose.

Photo of result is attached. I was really surprised.

Either way; I cleaned and re-lubed the the threads.

 

[3_gun]

That looks like Loctite residue on the threads, maybe the lube used wasn't meant to be used on aluminum ?

 

[aznsx]

What part of "regularly took both caps off" was written in French???

Sadly many people around here write better than they read.

Good job of getting it done w/o strap wrenches.

I do wonder why it seized so hard, so I wonder about the thread lube you used previously. It may lack the sort of Al anti-seize properties you might want. People have discussed thread lube on this forum ad nauseam (looks like the sticky thread on the subject is up to 72 pages, and people still start new ones all the time!!), so I won't even go there, but there might be something more optimal that you could use to prevent reoccurrence of the seizure.

 

[jcvjcvjcvjcv]

That looks like Loctite residue on the threads, maybe the lube used wasn't meant to be used on aluminum ?

I had the same idea regarding the blue-ish stuff. Maybe some co-worker "pranked" me when borrowing my light. Loctite 243 (blue) and 270 (green) are relatively close by. But I highly doubt it. But the white stuff looks like some sort of corrosion. I've had a alu bicycle frame corrode under the paint, that was all white too. And the galvanic corrosion between stainless steel bolts in aluminium was white too if I remember correctly.

I used petroleum jelly as I've done for years and years without any problem. The front cap got the same treatment.

 

[aznsx]

I had the same idea regarding the blue-ish stuff. Maybe some co-worker "pranked" me when borrowing my light. Loctite 243 (blue) and 270 (green) are relatively close by. But I highly doubt it. But the white stuff looks like some sort of corrosion. I've had a alu bicycle frame corrode under the paint, that was all white too. And the galvanic corrosion between stainless steel bolts in aluminium was white too if I remember correctly.

I used petroleum jelly as I've done for years and years without any problem. The front cap got the same treatment.

Yes, Al oxide is indeed white. In industrial apps, we use some 'no-al-ox' type stuff or anti-seize stuff to prevent / minimize that / such seizure. Now that you've experienced this, you may want to reconsider what you're using. I probably would, but that's just me. I'm professionally into 'problem avoidance' though.