Polishing a Turd (aka the Gearlight S2000)

[Sirstinky]

It’s been a while since I did a build thread for you all, so here’s one I’ve been ruminating on for a while. I reviewed this light a few years ago for 1Lumen (along with the smaller Gearlight S1000) as part of “the most popular light on Amazon” reviews. Link It’s a 4 AA powered zoomie. It was pretty basic with just a screw-in hollow aluminum pill with a pressed-in shelf, telescopic zoom head, 3 mode linear driver, and a fake xm-l2. In short, it was expectedly bad, but had some endearing qualities.

I have a soft spot for zoomies, and decided why not do the right thing and spend hours and hours planning, trouble-shooting, brainstorming, making custom parts, add enduring much frustration and tool-throwing to make it into a viable, practical flashlight. I did this to the S1000 and it turned out okay, so why not? Hey, it’s only a bad idea if it doesn’t work, right? If youtubers can take dried up animal poo and make it shiny, I’m sure I take a terrible Amazon zoomie good. Here’s the basics:

Host: Gearlight S2000
Battery: 26800
Driver: 26 mm mountain electronics FET+7135
UI: Bistro
LED: L90 9090 size round die 50W on 26mm mcpcb

Problems:
Batteries. The light uses a carrier with 4 AAs in series. It’s roughly 120mm long and the 26800 is 80mm long so a roughly 20 mm gap to span (actually closer to 25) somehow between the base of the pill and battery top. I ended up going for a 30mm OD, 24 mm ID aluminum tube cut to length. I’ll braze this to the base of the pill.

Heatsinking: The stock pill is very hollow with a 2mm pressed-in shelf. It was bent from the factory from excessive pressing force (the tool mark was visible) so that had to be fixed. Im cheap, so I cut up some old PC heatainks to size and ground them down to round to fit snug in the pill then aluminum and will braze them in place.

More to come on this one as I get along (photos and such) so stay tuned!

[Sirstinky]

Here’s some progress on the Gearlight. All the parts are here! The LED arrived from the Orient this week, so I’m ready to start fabricobbling. Below are the L90 LED and the Mountain Electronics 26mm FET+7135 driver.

Step one will be fixing the lack of heatsinking by adding thermal mass to the pill. There’s a lot of room in there!

I’ll be filling up the space with an aluminum slug made from a couple of cut-up PC heatsinks (below), plus remains of the fake XM-L2’s MCPCB and the original pressed-in ‘shelf’ (you can clearly see the divot from the overzealous press tool) which is about 10 mm total thickness. This will be adequate mass for the roughly 50 watts of output.

Step 2 will be fixing the main issue with this project: Switching from 4 AA to 1x26800 li-ion. There’s a roughly 25 mm gap to span between the top of the battery and the bottom of the driver. I settled on extending the pill (which also adds thermal mass) using a piece of aluminum pipe. I cut it to length to fill in the space. The pipe is 30 mm OD, and needs to be roughly 29 mm OD to fit inside the battery tube, so I’ll grind it down on my belt grinder (later) then aluminum braze it to the bottom of the pill. The blue line is roughly (probably less than that) how much I’ll grind off to get a nice solid mating surface (also for beveling before brazing).

That’s it for now. Up next: Some hardcore grinding and cutting action, high-speed skin removal (hope not), followed by some fire and molten aluminum (hopefully no 2nd degree burns or unintended fires).

Stay tuned!

[Sirstinky]

Here’s some work I did over the weekend. Sometimes I forget how much work goes into this stuff (doesn’t help that I do it the hard way). The objective: Improve the thermal properties of the stock pill so it can accommodate a properly high output LED.

Step one: I took the cut-up pieces of heatsink and refined them on the belt sander a bit before brazing them together. I secured the parts in a nice aluminum sandwich in a clamp to keep them from shifting. That went fine, issue was that the ultra-cheap aluminum MCPCB didn’t want to bond to the rest of the parts, so I had a heck of a time getting good fusion. Took three attempts, with the last one the best. I’m using Bernzomatic aluminum brazing rods and a propane torch for this. If you haven’t tried aluminum brazing, it’s awesome and works surprisingly well. That’s a piece of mica fire-resistant material protecting my clamp.

Finished!

Next, time to mark the rough area I need to remove to get the billet to fit into the pill and get to cutting/grinding.

I used my small hacksaw to remove the big areas, and the belt grinder to finish (used 1x30 80 grit zircon oxide belts). When grinding with power tools, don’t forget that your eyeglasses aren’t a substitute for safety glasses.

The billet fits fine and fits flush against the back of the shelf. There’s some gaps, but that’s intentional since it will be filled in with brazing filler. Previously, I re-pressed in the shelf (after removing the divot and flattening the warped areas) using a 19 mm 1/2 drive socket and some blows with the 1/2 ratchet (what, I couldn’t find my hammer).

After brazing (which takes a lot of patience and heat and nearly giving myself a fire haircut), there’s still some gaps to fill in. I called it a night at that point.

I picked it back up the next day, completely filling in the gaps. This time the penetration is complete, and the pill is completely filled in now much heavier.

The marks from the socket are still visible in the shelf, but i’ll sand and blend those in (they aren’t deep at all).

Next step is the pill extension. It’s too wide, measured at 30.5 mm and needs to be roughly 29.5 mm to fit inside the battery tube, so off to the grinder. I mounted the tube on the handle of a skewer and allowed it to spin as I ground down the outside diameter, checking with the calipers every so often. Gloves are mandatory here unless you like getting friction burns and don’t like having skin on your fingertips.

Success! The tube fits in the tube fine, and after some finishing with a mill file to flatten the edges, fit-up looks good. I’ll bevel the mating surfaces before brazing them to get a good strong bond, but that’s down the road since my blowtorch died. The control valve retaining nut was previously broken and I fixed it with RTV silicone to keep propane from leaking out and catching fire during use years ago, but the fix wasn’t meant to be permanent, so the torch is down for the count.

So, on to the next item: The switch. The switch is a cheap, no-name Omten clone and seems to look okay and has a nice click action, so I may keep it, but the spring setup? I may end up bypassing the spring with solder wick and leaving it alone otherwise then fix it for real when (or if) it melts.

That’s it for now. Stay tuned for more. Next steps, fixing the switch, cutting a driver pocket, and brazing the extension to the pil.