DIY EDC AA: The Franken Light (build log)

[PlanBTorches]

Hi All,

I'm starting my first flashlight build and I thought it might be fun to document the process here for the entertainment value and (if any kind soles wander by) the feedback. To kick things off I'm using store bought internals from mntelectronics (selected mostly at random) and sticking with a pretty standard three part design (see renders). To keep things easy the material is 360 brass, and I'm building without a pocket clip for this round (I've been struggling with how to handle the heat treat). My goal here is to build some design intuition and get some experience with the various machining operations involved. I do plan to learn more about LED selection and driver design, but that (along with the pocket clip) is for a future project.

Design Notes:
I plan to use a 0.9x40 thread for holding the three sections together, and the mcclickly thread for both the pill and switch. The pill will made of either copper or aluminum depending on whether I can find a not-totally-misserable-to-machine copper alloy to work with (thoughts appreciated!). The two barrell o-rings and one front o-ring are both set up for around 5 thou of compression when the light is closed up.

The Parts:

1. 45 degree TIR from Mountain Electronics.
2. Nicha 316 LED board from Mountain Electronics.
3. MISC AA driver board from mountain electronics.
4. mcclickly tail switch.
5. Various o-rings from mcmaster carr.

I am totally new to this, so I'd love any thoughts, feedback, opinions, or comments that come to mind! I'll post more updates as the project progresses.

 

[KITROBASKIN]

Hope you have satisfaction with this! Even some fun!

Quite the figurative expression, “if any kind soles wander by”.

Not sure the underside of our feet are able to show kindness enough to be recognizable. We can make an effort to not step on you though.

 

[desert.snake]

I would add a couple of ridges on the body or other protrusions to keep it from being too slippery, but it looks really good

What type of use was it intended for? If I had to make a tank, I would add metal in all places. But I remember a company that made extremely durable lights - Texas Lumens flashlights and they went out of business. The main thing is to have a balance of characteristics and beauty. Therefore, this picture below should be taken very-very-very skeptically. Maybe other than the pill. If the driver is very powerful and the diode is hot, need to direct thermal way

 

[PlanBTorches]

@desert.snake: I've been away from my computer over the holidays and coming back to that design (which my fiance has dubbed the "beast variant") is a real treat. I really like your point about the slip and the direct thermal path definitely warrants A/B testing. Adding a protective lens to the front seems like it would provide some great waterproofing and impact resistance at the cost of added fabrication complexity. I'm going to stick with the current design for this build, but (with your permission) plan to try something like what you posted for prototype two, I think it'd make for an interesting comparison.

In terms of use case, this first build is mostly just to get familiar with the components. In the long run I'm aiming for a light that will shine as lab/shop EDC (so looking inside equipment, finding parts that have fallen and the occasional sensor test) while also performing well in a hiking / car-camping type role. Waterproofing at pressure doesn't matter, but I definitely want enough water resistance to survive a coolant tank swim. Probably that means the priorities are: high mechanical durability, decent run-time, flexible battery support and decent (but not great) waterproofing.

To kick off the build log part of this thread, here are the electrical components set up and working together:

I'm sticking with the pre-made components for this build so no real surprises. Next up I need to dial in the o-ring tolerances, and get started on a 3D printed mockup.

 

[PlanBTorches]

Continuing with the build log, I've now got all the parts in got the chance to mock things up in plastic (see below). The tolerances were not close enough to fit-check everything, but I did get to verify the o-ring seals were sized correctly, and that the light feels nice in the hand.

Next up will be machining, and that may or may not involve something of a delay. I'm in the somewhat odd position of having access to a Tormach 1100, but not a reliable lathe. Since I plan to thread-mill the threads anyway, it may make sense to interpolate most of the metal removal. If that doesn't seem viable I'll have to wait until I can get the lathe squared away. In any case, I will update the thread once I know more.

 

[PlanBTorches]

Okay, it's been a good long time since I posted here, a bit over a year by the look of it, but that doesn't mean the project is dead!

Here's a picture of the newly finished "component wrench" I plan to use for installing the pill. This was also my chance to test out some things on the local Tormach, and I have to say it went great. I've got a few more pieces of tooling to make before I can get to the light itself, but I'll hopefully have some more updates to share soon.

In the meantime, one thing I've been thinking about, and would love input on, is the pill material. I'd originally planned to use copper, but it looks like Aluminum is a pretty close second for heat transfer (and of course much easier to machine). Any thoughts or input on the matter would be greatly appreciated.

 

[Hoop]

Nice going.

Aluminum will work fine for the pill and is lighter weight. It's also easier to machine as you say. Bare aluminum on bare aluminum or bare aluminum on copper can have a tendency to gall, but using a somewhat coarse thread such as 32 tpi or coarser, and cutting to the mean tolerance of the thread should prevent an issue. I make lots of 32 tpi bare aluminum stuff and it's fine without lubricant. If the thread fit is too tight, not enough wiggle, then you can get galling and the threads will weld themselves together upon removal. If your host is brass, the galling issue is much less of a concern. On this matter I can say that I have made 50 tpi brass driver retaining rings, which thread into a copper pill with very little thread clearance, and galling has not been an issue.

Machining copper in the mill is best accomplished with sharp 4 flute cutters in my experience. 3 flute high helix cutters are pretty grabby. Despite being soft, copper wears carbide cutters somewhat quickly. Using coated cutters should prolong the cutter life a bit.

Avoiding mixed metal machining helps keep the galvanic corrosion down in the mill. If you do machine copper or brass and aluminum in there, be sure to clean the vise well, and not long after the job, remove it from the mill table and clean out the chips from underneath, otherwise the T-slots will be corroded. But maybe you guys already know this.

Interpolating the thread in the Tormach should work just fine. I threadmill and make "lathe parts" in my VMC all the time.

If you have any questions about flashlight design or machining, feel free to ask.