Modding a mini C8 - need some ideas...

A while ago, I took apart one of these mini C8s to see how they are built. Here's the thread:

Now I had the time to start my modding attempt, and it works, kind of, but not very good, so I think I'm going to need a few new ideas. But first things first.

Here you can see the original plastic pill and reflector on the right along with what I'm going to put in: copper cap, leftover XR-E Q5 and TIR optic.

The driver is a boost driver from Fasttech. Note how the ground ring is slimmer on the FT driver. In this flashlight, the end of the battery tube touches this ground ring and completes the circuit.

Now because of this slim ground ring I wasn't sure that I would get good contact with the battery tube. Moreover, there is a curcuit trace on the driver that I was afraid to short.
So I soldered contact wires to the ground ring:

I ground the top of the copper cap flat, drilled holes, secured the emitter with arctic alumina and soldered the driver wires to the star, no problem.

But from here, thing start to get a little bit finicky. Remember that in this head, everything has to go in from the front. Seems that I have two major problems here:

1. The copper cap and the driver have the same OD, so I couldn't solder the driver to the pill, instead the pill has to keep it in place somehow.

2. Everything (driver, pill, TIR) slides without any friction into the head, so I have to make it press-fit somehow...

At first I wanted to wrap the pill in aluminum foil, but I couldn't get that thing shoved into the head. So I just crammed three pieces of stiff copper foil in there:

The TIR just pops on top of the emitter, ready to go for a first try.

Screwed the battery tube on, works first try!

But here's the BUT: With the copper around it, the pill has enough friction so it doesn't fall out. But obviously, if I screw the battery tube against the driver, everything will start to move forward, the connection just doesn't feel solid. Also I figure that the TIR will eventually pop of the emitter when the flashlight is dropped.

SO if any of you experienced modder has an idea on how to secure everything in the head I'd be grateful. Up to now I only did parts swaps, but this is my first major reconstrucion and I feel like I have come to a dead end here.

By the way, that Fasttech boost driver is quite a beast! Draws 1.7 amps from an AAA eneloop. Did I mention that the modded light blows the original one away big time?

Your correct with what you say about not being solid. If you screw the battery tube in to hard it pushes the TIR out making the earth not make contact. I havent tried this on this light but will on the next one coming. It needs a groove to hold the ring in and Ive just by accident tonight found that a full turn of the large spring cut off from a P60 dropin will fit perfectly. This is the light that I did this on.

You can see the ring in the first picture.

Heres a link to my modded mini C8’s.

Thanks for your input! Your builds are always awesome.

i did almost the exact same thing to one of those but i kept the stock driver and used an xml

I had to shorten the copper cap or the tir wouldn’t fit.

I just glued the TIR in place. be careful not to get glue on any part of the tir except the lip or it screws up the beam.

also, be careful not to overtighten the tail cap because the switch can easily get pushed out the back by a battery.

What kind of glue did you use? Epoxy?

hot glue, so that i could easily take it apart if i need to

it was kind of tricky and took a couple tries. i had to warm up the head to get the glue to stay soft long enough.

if i do another I’ll use super glue gel.

Nice build Steve_the_Chief. Sounds like it will be fun little light when you are done. dthrckt’s hot glue approach sounds good. It sets fast (don’t have to wait for curing) and it’s usually reversible with little to no damage.

The reflector that came with the light looks good. Why not stick with that?

I did try the reflector with an XR-E and the beam looked horrible... Maybe with some trimming of the reflector bottom it would turn out ok, but I decided that this would be too much effort. Especially since I would have needed a new lens then.

White wall comparison of modded and unmodded light:

I put a flat aluminum washer between the bezel head and the TIR optic. You can leave it as is or epoxy the optic to the ring. This should hold it in place. Sorry no pics. They were all gifted.

BTW - looking at your soldered emitter pic, you should clean off the flux (residual brown colour flux) after you solder with a Q-tip and some alcohol. Besides preventing oxidation and corrosion depending on the type of flux, it just looks better. Tongue Out

Hey Bigwood,

did you do the washer thing with this exact light? Since it has no screw-off bezel I can't imagine how you could keep the washer in its place.

You are perfectly right about the flux, I almost always clean it off, just sometimes I'm kind of impatient, especially if I want to see if it works or not

The washer I'm talking about is probably not the one you are thinking of. It's not a metal washer for a bolt. It's simply thin sheet metal that you cut to size. In my case I find one with the inner diameter already cut, most likely by machine or punch. I just trimmed it by hand to fit and flexed it/folded it into the head. Let me know if that makes sense.

Ah, I see. So you basically made the washer press-fit inside the bezel to lock the optic in place?

Yes similar to the type of washers Solarforce uses between the screw on bezel and glass but theirs don't keep the lense from falling out. But in this case you would make it out of thin sheet metal (aluminum). I suppose tin can or pop can material may work.

Nice mod, I got a mini c8 today and planning to mod one like you.
Gets the driver/pill only pushed out the front?
Which size has the copper you used?

What about glueing the tir in place? I know it could mess up the beam but maupybe worth a try…?

Edit: I cracked the glass…not sure how anyone can dissemble it without destroying…
The plastic pill is 16.5mm wide and the plumbing copper is 15mm so I guess a 15mm cap will fit.
But I have no really good fitting tir, the cheap ones are too small and the carclo tir have a weird bolt on the side…