Received the flashlight from Pavlo about a year ago. The plan was to replace the stock low CRI XPL-HI with any high CRI LED. But Fenix is well known to love blue and red thread locker. Even the blue thread locker they use which designated to be removable is almost unmovable in many cases. This is my longest fight, because we really want to put as little damage as possible for this is a very fine light. Flat regulation, sensible output, unique efficient zoomable TIR optic, great built, completely waterproof zoomie, ultra reliable, and…expensive.
I decided to try to open it only whenever I have free time to avoid frustration and too keep up my “will power”. So far, this is the HARDEST light to open for me! With no spare optic available easily, no destructive prying is possible. And I’m glad I didn’t do any brute force on it.
Original FD40 image taken from Fenix website. I forgot to shoot it.
Making hard wood clamps:
First try, broke the weak aluminum C-clamp.
Second try, stronger steel vise. Heated it carefully to no more than 120°C to preserve the PMMA optic. I glued a thermocouple to a location near the joint I worked in.
First encounter with the thread locker!! Fenix was very generous about it. Not a drop or two, they bathed the thread with it
This is “just” a blue grade thread locker. Just imagine what if Fenix used RED grade…. :confounded:
Now Only the head assembly left to open. Took me several months to figure things out. Heat it to 120°C, soaked the whole head in a warm kerosene batch for days, ultrasonic it, X-ray it, bang it, twist it, freeze - thaw it, asked nicely, etc….to NO avail
And last month I decided to try my last fight. The plan was to make a special wrench OR destroy the TIR optic to see what needs to be done (I was afraid it uses counter clock wise threading). I decided to make the wrench from aluminum scraps. This is the most expensive removal tool I’ve ever make to open a flashlight.
Part of the head removed effortlessly at ~240°C. Being aluminum I had to work very fast, it cools down rapidly. My hands got burned in the process too. Went all out. put the whole head on my hot plate and heated it to 240°C. I can always custom order the TIR optic. It’s been messing around for months and now it’s time to melt it!! :smiling_imp: To my surprise, the PMMA optic survived! The only visible damage is the frosted part is now slightly clearer, Everything else looks the same and still collimate the beam as it used to be.
Look at that, there are still some more parts to be removed :weary: . And these last parts were the hardest to clamp with no positive grip (hence the special wrench was needed) and silky smooth anodized surface.
Making the wrench
Perfect fit, with just enough clearance
VICTORY!
UPDATE 190903: More detailed high resolution images uploaded. Click to enLARGE
Very complicated and not many flashlight made from this many body components (except the electronics) like this one. Closer look at most of Fenix lights, although the model are mostly looks “boring”, Fenix sets a very high standard for all their lights. Flawless finish, top notch quality control, everything are well though and not just an afterthought add on features. Perfect knurling for $100ish price point. I’ve seen a light more than ten times the price with defective knurling. Even the well hidden glued internals are perfectly machined. Next time I get a Fenix, I will not complain about the price. Solder joints are all very well made. This is the only made in China flashlight with true Pb Free execution (read: PITA to desolder)
Zooming mechanism. The inner part is fixed to the body, only the outside parts are movable (threaded to the head assembly)
The MCPCB sits on the pedestal and the wires made from very thin copper sandwiched in polymide socks. The flat wire connected to the second FR4 board.
Then a plastic cover hide everything to prevent any artifacts or shadowing. This plastic cover also secure and presses down the MCPCB to the pedestal (Sandwiching the base FR4 PCB to the base using 2x M2,5 screws).
Defrosted TIR lens (the inner side center was frosted) due to heat used in removal process
Plunger style high quality stainless steel switch (secured with circlip)
I giggled in awe when I saw this precision made 18650 BATTERY SPACER. Other brands use cheap plastic tubing, but Fenix made it from silky smooth perfectly round anodized aluminum! The spacer secured by a ledge at the base. Why not just plastic? IMO, this is a luxury impractical stuff.
To those interested in FD40 driver. I did y best to capture all the part numbers on the components:
If you guys need more detailed information, just let me know. I haven’t found any tear down pictures of this rare FD40 anywhere.
[Clemence]