James C's 13th Old-Lumens challenge - Handmade

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This year I’d like to build a light. Wait, I’m getting ahead of myself… This year I’d like to finish an entry, preferably in the handmade category. For the past several years I’ve set out to complete a project for the contest but I’ve yet to finish one. This year will be different!

I have accumulated many modding parts over the last few years. I’m guilty of impulse-buying parts online with vague ideas of what I’ll use them for. Well, now it’s time to make a light - ideally without needing to buy anything.

After much deliberation, I plan to use some pieces of copper pipe, and a few off-the-shelf parts, to made a compact AA/14500 light.

Here is a general layout of the parts, from top to bottom:

  • Convoy T3 for reference.
  • 16mm ID, 18mm OD copper pipe (I’ll call this the outer tube).
  • 17mm TIR sold by Convoy, 16mm MCPCB, 16mm MCPCB for use as a shelf, “1/2 inch” (not exact) (actual 14.5mm ID, 15.9mm OD) copper pipe (I’ll call this the inner tube). I kept this pipe after re-plumbing my house. It’s from 1978.
  • 17mm driver. This one shown is a placeholder. I will likely use the one from the T3, which has no spring and supports both AA/14500.
  • 14500 for scale.
  • I think this is Convoy’s 15.8mm switch, copper spacer from 1/2" pipe, Convoy aluminum switch button.

General design:

  • The inner tube will have a shelf soldered onto the head end. It so happens a standard 16mm MCPCB is the perfect size for the shelf (though I wish it were thicker - I made double it up). It is the correct diameter and already has notches removed for the driver wires. I’ll simply sand-away the MCPCB’s solder mask down to the bare core.
  • Starting about 1cm down from the shelf, I will cut a notch out of the inner tube to place the driver, which will need its diameter reduced. The notch will remove much of the tube in this area. This will allow me to solder the driver’s normal body tube contact ring to the inner tube. This is hard to describe but I think it will work for retaining the driver and making electrical contact.
  • The end of the inner tube will have a bayonet-style connection for the separate tailcap.
  • The outer tube will be two separate pieces. For the head, a copper ring will be soldered on the end to act as a bezel to retain the TIR. The head portion will be long enough to cover the “driver notch” of the inner tube. Come final assembly time, I will glue this head portion of the outer tube to the inner tube.
  • The tailcap will house the switch spring and mechanism. The switch board, mechanism, and button are all within the ID of the outer tube. A small piece of outer tube will encase all of this and slide over the inner tube when the tailcap is installed. It will be retained by a bayonet-style system, i.e. two small nubs on the inside of the outer tube portion will fit into a channel cut into the inner tube. “Push on and twist” to lock on the tailcap.
  • Visually, the outer tube “head” will take up about 50% of the length. Roughly 20% in the middle area will be exposed inner tube. The outer tube tailcap will be the remaining 30%. The plan is to be roughly the same length as a T3, but smaller diameter.
  • I haven’t yet decided if I will install a clip. It would likely entail tapped holes in the tailcap.

Challenges / Concerns (so far, ha):

  • Though the inner and outer tubes have a pretty tight fit, I worry about thermal conductivity between the two tubes.
  • I don’t want this to look like plumbing parts thrown together, so I will experiment with ways to engrave / finish the copper.
  • I have never made a bayonet mount (or made an entire light like this, for that matter). I want the tailcap to install smoothly but not wiggle around in use.

I started the project a couple nights ago. So far I’ve cut some of the tubing, soldered on the bezel ring, and started on the tailcap. Soon I will make a post dedicated to the tailcap, as that’s the most interesting part so far.

Hopefully you’ll enjoy the build!

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2

Very cool!

Regarding the etching, I’d consider chemical etching - copper is very reactive - you could mask off an area and choose your poison. Just an idea!

Cheers!

1 Thank
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Thanks for the suggestion! I hadn’t considered masking off an area for etching. I have a laser engraver that I could use to create the mask design, though I would have to make sure that doesn’t put me in the machine made category.

At the very least I will probably force patina some of the pieces. I like the contrast of a very dark patina and polished copper.

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You could probably x-acto an old vynyl sticker and apply that to the light for masking - depending on how complex the design/steady your hand is! I’d imagine bringing the machine out to do the cutting for you would bump you out of the handmade category (*but I don’t make the rules! I’m new here!)

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I made some progress recently. First, I made a design change. I decided the Convoy T3 driver wasn’t going to easily fit so I switched to an old Foursevens AA driver from a light I irreparably damaged while trying to open it up for an emitter swap. It’s an ok driver. It has low-medium-high without mode memory. It unofficially supports li-ion.

I notched-out a space for the driver in the body tube using a rotary tool with a cutoff wheel. The notch design is to allow a single piece of body tube to house both the driver and the LED shelf. The notch allows me to solder the driver to the body, thus making the needed electrical contact while holding the driver in place.

Note, the driver is not yet soldered to the tube and it’s not held in place so it’s sticking out a little in the pic. The cutout just below the driver is to remove thermal conductivity from the rest of the tube to make soldering easier when I get to that point.

Here’s another view. You can see most of the tube is removed in the driver area. The LED shelf is simply an upside-down 16mm MCPCB soldered to the body tube. I recently got my first hotplate which made soldering the shelf very easy! I previously would have used a heat gun (like for paint stripping).

I cleaned up the tube with some Brasso and a woven sanding wheel on the rotary tool. It’s the same tube as in the pic from my first post - big difference! I like the brushed look it has but I may end up trying to force a dark patina on this piece.

I’m preparing to do the tailcap next. I’m not too worried about the tailcap (I think I have a good plan and the hotplate will help a lot), but after that I’ll need to deal with the bayonette mount for the tailcap - thus the potential to mess up the body tube and all my progress.

More to come soon. As long as nothing goes wrong I should have no problem finishing on time this year! (fingers-crossed).

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6

This looks amazing!
Can I ask, did you remove the conductive layer from the mcpcb so that it was direct copper making contact with the tube

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Thank you. Yes, I sanded the MCPCB down to the bare copper substrate so it could be soldered to the tube. I placed a sheet of course sandpaper on a table then, holding the MCPCB down with finger pressure, sanded in a figure eight pattern.

Using the MCPCB as a shelf was one of those fortunate design solutions that work perfectly. It’s cheap and on-hand, the exact size needed, already had cutouts for wires, and the sanding was easy. If only the rest of the light design would be so lucky.

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