Rook with 18500 Conversion and True Lockout

Got Rooks for me and my wife from a Wallbuys' special. I tired of the parasitic drain soon after. I attempted the incredibly creative fix from The Last Katun's Rook mod thread a couple of times. Both failed after time from scouring by the cells. I blame the failures on my choice of plastic materials in both cases, not on The Last Katun's mod.

One time when removing cells, I found one cell was completely drained while the other 2 were full. Investigation showed the plastic deformed under pressure from the cells, but returned to position when unscrewing the battery tube. The thought of my wife unlocking this tightly built light in such a situation chilled me. I shelved both lights despite being very fond of their compactness and beam pattern.

Now, thanks to this 18500 deal alert thread by Gj, I scored some like-new 18500's at an incredible price. Thanks Gj!. This motivated me to finally attempt to fix the fatal flaws of this light (multiple 14500's and parasitic drain) and yet still maintain Ni-mh compatibility and even the ability to use 14500's in a pinch.

This mod is simple. Bore out the center to allow a 18500 to fit and replace the springs with copper domes so the light has a twistie lock out. No modification to the driver is necessary as it accepts positive at the center contact pad.

Here are pictures of mods so far. The final pictures shows a way the light can be used without the lockout mod. I will post the lock out mod once I finish it.


Bored out with dremel grinding stone and a hand file:

The below pictures will not be part of the final mod. They are just a quick and dirty way to use an 18500 without doing my lock out portion of the mod. Here is a great, simple, reliable tail lockout created by DenBarrettSAR. If you combine this mod with his, you probably will need to Kaptan tape the bare aluminum in the battery tube and also on the sides of the copper disk.

The cell contact plate is just a copper disk with 3 tabs bend down to clear battery tube.

Lockout Mod:

Made a copper plate with copper domes to replace the negative battery board above. Made a flat plate to fit under it for added support. Drilled holes for the 3 mounting screws. Sanded off the anno on the battery tube where the plates mount. Assembled.

Spring wasn't used:

Softest screws I have ever encountered:

14500's sit lower because I forgot to put contact bumps in plate for them. That will have to wait until the next time I open the light. I got to get some sleep for work tomorrow.

Other than 14500's, the light works great. Just slightly unscrew head and its locked out. I imagine you can't get a much lower resistance tail setup than this. For using 14500's, I like DenBarrettSAR's lockout mod better. His mod will keep the 3 cells in contact with each other an in balance.

Great mod, 3 Sanyo 14500's from Fasttech costs 10 times as much for only 48% more capacity.

Is the tailcap glued? Can't budge mine.

You did a great job there. :bigsmile:

Nice job !
I thought about doing something similar (since the Rook can run on everything from 1.5 volts up to 4.2) but boring out the entire body on a Milling machine, and modding the tail cap, to accept everything from a single C-cell, to a 18650 &26650, ( using sleves) and can still use 3 AAs, 3AAAs, three 14500s, or three 10440s, using a modified 3-cell battery holders. ( basically similar to a Lumintop SD10 idea)

Gj wrote:

Great mod, 3 Sanyo 14500's from Fasttech costs 10 times as much for only 48% more capacity.

Is the tailcap glued? Can't budge mine.

Thank you. I calculate 33% less rated capacity, but actual loss is less because I'm getting 1800mAh from the 18500's and less than 840mAh from the 14500's. I expect the capacity to increase with some usage. Nightbird95 was getting close to 1900mAh with his Sanyos here.

To me the safety gain is worth the capacity loss. And, I will still be able to use 14500's when I want to.

Yes, the tail cap is loctited. I used a heat gun. Once you get it to the right temp is screws off real easy using leather gloves.

EDIT: You may need to use a strap wrench if they really torqued down the cap. Luckily, both of mine were not that tight. Not sure if you know, but loctite is basically plastic. Once you warm it to the point it melts, it serves more like lubricant until it starts solidifying again.

Thank you Panther and DenBarrett.

DenBarrett, that sounds like a real nice mod idea. I hope you get around to it eventually. That would be a big upgrade to the Rook.

EDIT: DenBarrettSAR has created a great simple tail lockout mod that will be much easier to execute then mine will be. I have linked to it in the OP.

I've been playing with a couple ideas on design of the tail "spring". My original intention was to use no real spring and just screw down something like the below "dome" to the battery tube mounting surface. Using an actual spring like below is another way to go, but would require more turns to lockout the head though. It will also add more points of potential resistance.

The below contact plate "dome" is a first draft, but is probably good enough. The dome will flex under pressure, but the shape will keep it from collapsing. It just needs bumps added for the 4 cell contact points.

I like the idea of solid copper everywhere it can possibly be used in a light, (reducing resistance) I thought i remember seeing somone here on the forums build an entire light from copper once ?

Thanks. I picked up a heat gun at the last Harbor Freight tent sale to shrink wrap cells.

I've been using the same el cheapo heat gun from HF for years. Tough, reliable tool. I've even used it for auto body work like rolling fenders and such. For flashlights, you probably will never need more than the low setting. Try using it for reflowing emitters. It's the best way in my opinion.