This will serve as my build thread for this year’s 5th Annual Old Lumens Scratch Build Contest. I am entering the machine made category. This will be my first ever scratch built light. I have done plenty of mods and made parts in the past but have never made a full light, so I am excited to see how this goes.
Not entirely sure what I will be building yet, but I do know some basics, in that I want to build what I see as “the future” of mass produced lights, which incorporate things that I want to see become standard in the flashlight world from makers like Convoy, Lumintop, Jaxman, Thorfire, etc. Specifically, I want to design a light that is based around a 21700 battery with a driver size of 22mm. I also want to use modern low Vf emitters with good tint and high CRI, and a driver that maintains regulation through the entire discharge of the cell, and is PWM free.
On the driver front, some of you may recognize me as the guy who has been reverse engineering the Kaidomain boost drivers, and has also started the design process for my own boost driver. I would love to use my own custom driver, but I am not sure the MP3431 Boost IC will be available yet, so a heavily modified H2-C may have to be a stand in. But be sure I will at least document all of my modifications and use some custom firmware so others can follow suit.
Currently my two main ideas are to build scaled up versions of my favorite 18650 lights, being the Convoy M1 and Jaxman E2L. Still tossing around ideas though.
Yep, pretty sure the E2L driver pocket is basically the same as the Convoy C8, M1, M2, so if the pocket is bored out a bit combined with filing down the driver edges to the vias, it should barely fit under the stock retaining ring. I plan to do this exact mod myself whenever my extra drivers arrive to play with.
No triple XHP35, well, maybe, nothing is totally ruled out yet.
Mostly I want to use H2-C because I want a 22mm driver pocket, as I feel 22mm should be the standard for 21700 lights when they start being produced.
Technically the H2-C MP3428 IC supports higher power output on paper too, but the thermal design of that PCB probably limits it to about the same as the H1-A TPS61088 driver in real world usage. I plan to investigate modifying the H2-C to reduce the output voltage though, as it should drive 6V and 9V setups no problem as well with the right feedback resistors.
Thanks! Taking my first cuts. I’m just going to start with the 21700 tube light because I’m almost positive I can get that done in time, if it goes quicker than expected I’ll try the scaled up M1 as well.
EDIT: Sorry if I format this all wrong, but I am going to start putting all the pictures in the reserved posts only after this one.
Really all I have done so far turn the outer diameter of the battery tube to see how it looks, I like it so far. Unfortunately the x-axis on the lathe DRO has gone whacky, so I’m back to using the knobs and measuring manually.
I’m also drawing some parts in solidworks and looking around Kaidomain for lenses, reflectors and switches. I’m considering a few different optics too.
Anyone know where I can buy a Samsung INR21700-30T? I realized I don’t even have a 21700 battery to check the tube sizing.
Been awhile since I updated this. Ordered some tools from China almost 2 months ago, and they finally came in last week. So had a chance to do a bit more work.
As of now, plans have changed, I decided a tube light on this scale just wouldn’t look right with the Khatod quad optics I want to use, so instead it will have a slightly larger head and tailcap than battery tube.
Speaking of battery tube, I finally figured out how to thread on my lathe, so the tube is done! Final dimensions are 25.4mm OD, 21.5mm ID, 75mm long. Threads are a weird mix of metric and inch since I couldn’t get the metric pitches to work right. Its a 25mm major diameter, 22.9mm minor diameter, and 18 threads/inch.
Next I will probably try to get the tailcap machined, and will see how internal threading goes. Now, on to the pics
One side threads about done, first time cutting threads on this lathe.
Shaved to length and threaded the other side, as you can see a 21700 fits nicely.
Sandblasted to clean it off, and because I just like the finish that way.
Had a little bit of time today so I made the copper insert for the light engine and started the head. Cut my first internal threads on any lathe ever, and they actually work!
Right now the plan is to have the head be mostly aluminum, then have a press fit copper insert that holds the MCPCB and driver so I can solder the driver in rather than having to make a retaining ring setup. Not sure my tooling could even do threads fine enough for that. On to the pics!
He did a review of those: 
