[COMPLETE] wcddesign's 9th BLF Old Lumens Challenge entry - incandescent penlight

I’m new to the forum (and high quality flashlights in general) but I have some time off from work and I have two lights I’ve been meaning to rebuild anyway, so I thought it’d be fun and motivating to do this with y’all.

The first is a simple incandescent penlight. I want to use nothing but the bulb and spring from a disposable medical penlight and basically just build a simple tube and switch.

The original runs on 2xaaa and the pocket clip is simply connected to -neg end of batteries such that pushing it down connects to an aluminum tube (through a hole in the plastic body) and the light lights up.

Will post pics of disassembled penlight with bulb and spring I intend to use asap. Still considering what the new body shape, material, etc might be.

Alright, gonna try to add some pics here…

A disposable medical penlight. The clip broke (it is also the switch)

Cut open with tube cutter. These are the parts.

The materials I was considering using to make new body. Copper, whatever this wood is, and maybe some silver.

I want to set batteries side by side (cut or bend the spring to sit under them both, keep bulb sitting on +pos of battery, and build similar momentary contact switch on opposite side of same end to complete circuit. Maybe side, we’ll see. Not end, because it will be too short to comfortably use switch on end.

I’d like to power it with single 10440 or 14500, but I don’t have one laying around :slight_smile: may borrow a 2.4v 14500 from one of my Olight i5r if it will fit in copper pipe…I doubt it will. Output would probably be perfect though.

And I suppose I will have to read about how to post pics here lol. Make an imgur account or something. Will edit this to fix images later. (Saw someone using the site so I thought I would too, but when you click on mine it seems to always show inappropriate ads which I don’t intend to contribute to)

>>> imgur account created and problem seems to be solved.

Welcome to BLF and the competition wcddesign. :smiley:

I use imgur.com , it doesnt show those adds.

Thank you. And imgur is what I plan to try. Won’t cooperate with my Android though so I’ll have to break out a windows box :slight_smile:

Lot of learning to do in a short period if I’m going to get this done. Probably busy visiting family all day today and tomorrow, so just letting the plan slowly coalesce ATM. Will try to get set up on imgur later tonight.

Still trying to decide how I might build the body. Primary concerns are how it will open and close to change batteries/bulb, and design for momentary switch.

I was thinking I’d try to cut a head out of the wood, easy to shape (relative to copper) I have some .5” 5/8” copper pipe I want to use but it won’t fit aaa side by side (even after reshaping) so I’m considering cutting open and making two tubes shaped like “D” with opening in vertical, and then soldering them together… kinda like “CD”.

In that case, switch would sit up in empty space at emitting end where bulb will sit on +pos of one battery and switch would sit above -neg on other. Primary concern at that point would be, how does it attach to “spring” to keep it off battery when not pressed. I’ve rounded up some small steel springs and have some choices there. Also, doesn’t necessarily have to be steel spring. Could be nonconductive material sitting atop battery with hole in it such that pressure on silver switch would compress material and put it in contact with battery. The main problem with this design would be that the bulb would probably be very difficult or impossible to replace. Incans don’t last like leds. I’d like to be able to replace the bulb.

Design for switch is dependent on housing, so while I’ve considered some options, I’m not at all sure how that’s going to shake out.

Still might power with single 14500. Normal 3.7v might be too high, but custom 2.4v should be perfect. That’d let me just use copper tube for batt. Might have to sand inside to widen slightly, but it’s close. Could cut wooden “plug” for head, epoxy to tube, maybe thread copper pipe cap and end of tube? duh, they wouldn’t fit together, lol

But then how would I build the switch? First thought is, could I roll a piece of copper off of the tube (just where the wooden read would meet the copper) and roll it to make a tiny tube to hinge a silver switch? Idk, but with that design the tube becomes the negative connection, and there is less wooden head to house a springed switch…

So many questions, but then that’s the point, isn’t it?

So, last night I cut a little block out of the wood and drilled holes for the bulb. 7/32 all the way through for the end of the bulb, and 3/8 about 14mm deep for the lower part of bulb.

I also found a magnet to put in endcap so, hopefully, it will be magnetic.

hacksawed off a block. might’ve used miter (did i spell that right?) saw but didn’t know if that was ok, plus this wood is dense)

used spring loaded punch to dent center to align drill bit (you can see where i missed the first time :smiley: )

this is how I held the block still to drill it

so the largest drill bit I had was 3/8” but i needed the hole for the bulb just a bit bigger. Enter dremel rotary tool with wood engraving(?) bit.

at last! she fits!

So, I started rounding off the corners with the same bit…

And it bit my finger! (The blood sacrifice has been made. ;o )

This is as far as I got on this night. You can see some of my sketches there in the background. I originally planned for the wood to show, the glass bulb to stick out from it slightly, and the copper pipe to stick out in an effort to protect that bulb from collisions.

Tonight I sanded the wood block (with a Dremel) to make it round and sized to fit inside a copper pipe cap (because that would make it the same size as the pipe, right?)

Then I sanded the lower half or so so that it would fit inside the pipe (used Dremel to grind burr inside pipe)

My small hole in the wood (for tip of bulb) was a bit off center. I said, “I’ll drill a cap and then see if I can salvage the wood part.” Well…

The hole I drilled in the cap was slightly off center as well…

Such that it was an exact match for the wood!

So, yeah. Might go ahead with just popping that cap on the end, since it seems like it’s just going to be that way.

It all seems to hold together pretty well with nothing but friction, so far, but I will probably use 2part epoxy to hold head, and it’s components, to tube. Might use some to hold magnet and spring in place in bottom of cap as well.

I intend to just let friction hold the tail so on, but we’ll see how that goes once it’s together and has battery and spring trying to push cap off. Might have to apply some skills I don’t actually have :stuck_out_tongue:

>>>>Again, will add photos ASAP

Still have to:
cut tube, deburr, clean up outside , and find battery spring (one that came with light was for AAA, I’ma go with 14500 2.4v Olight battery.)

Also, last hurdle feels the highest, find spring for and design/build switch.

Perhaps most difficult question left to answer: if I’m going to build this thing looking like just a short price of copper pipe with copper caps on both ends, should I use silver for switch after all, or keep it ALL copper?

I originally intended a different look (as seen in background sketches… and still might go for it, though I’d have to re-carve the wood and really could use a drill press to keep the holes aligned :smiley: ) where the wood would actually be a visible part of the light and the copper would have a different shape, and I thought that a bit of silver would nicely pop the switch out from the copper and whatever this dark wood is (sorry idk, someone gave it to me. It smells like burning cat pee when I sand it with dremel if that helps identify it :stuck_out_tongue: ) but if I go for the simple copper pipe… Maybe just force patina and protect…

Seems super simple compared to the others I’ve looked at, but I’m learning a lot that I can apply to the next build. I like my copper lights. This will be the first one I’m making myself. If I do a forced patina and protective coating those will be firsts for me, too. As is posting in a forum at all :slight_smile:

And it’s purpose built. It’s not a complicated light. I just want a little more function. The ability to change bulb/batteries and more durable. Using rechargeable battery is tradeoff I’m willing to make to get it to fit the materials I have available, still not “whole light is cheap and disposable.” I’m no expert, but I’m pretty sure it won’t be bright enough with just a single AA. And I didn’t want to make it bigger than the original with 2xAA.

Hopefully, next model will have warm led and maybe even brighter modes (though would need to open on VERY low, and have no memory function)

Not much progress tonight. Bought spray can of Rust-Oleum satin clear enamel.

Running some forced patina experiments overnight.

Removed a couple springs from a couple of old remote controls. One to place under battery, one might be used for switch spring.

Hope tomorrow to determine necessary length for battery tube and get switch built and working. Little measuring and math for length, probably just have to try a build for switch and hope I can adapt quickly if it doesn’t work.

I need to sit down and read all of your thread. On a side note i love the energy that you bring to the comp :partying_face: :beer:

Thanks. I’m trying to use the post to keep track of my process as best as I can.

If I do this many times, maybe I’ll do that some other way and not vomit my thought streams all over the forum :slight_smile:

I’m like 200… when I’m interested in something. If I’m not, it’s more like 12.

I enjoy it for the most part (because I’m built to?), but it makes life difficult in certain ways.

So, progress was made today in the form of failure :stuck_out_tongue:

Cut and ground switch from old penny. Had to reshape several times.

Cut slots in inner tube and wooden insulator to fit spring and switch.

Many mistakes were made. Hole in switch for spring was off center. It also probably needs it’s edges rounded. You can see in photos where the spring was damaged by pressing it. Finally, it is too large and contacts bulb even when not pressed. The wood was not cut properly the first time. (may still need modification) I used diamond engraving bits in rotary tool to shape it to allow spring some room to bend (may not be enough room though, will revisit tomorrow) Switch design itself may need some modification to it’s shape. It doesn’t feel quite right.

Switch (cut from old bronze penny) and spring damaged by my dumb…ness

Wooden insulator shaped (not enough I guess) for spring and switch to fit

Pipe (scrap piece) cut for switch to fit

Slot in inner tube (again, scrap, not actual tube) for spring goes down too far. could try shorter spring, but will probably need to file more wood from insulator to make it stick out less from tube (thus allowing cap to go on further)

Tools and things I used today.

I am running out of time to spend working on this and hope to have final product designed and built tomorrow. I feel like that round spring may be a problem… I have some flat spring steel I could try to use if I have to give up on the round spring, but that would require a redesign and rebuild of the whole switch and it’s slots in the inner tube and wood insulator.

Feel like I need to simplify some more… we’ll see.

I’m really happy to see you make a switch. It’s a good thing you’re dealing with low current. I wouldn’t trust myself to make a switch for something with high current throughput as there could be a potential fire hazard I miss when designing and building the thing. I look forward to your finished product. If you run into anything regarding working copper, feel free to ask. I might have run into a similar issue on my build and can possibly give some input.

I wouldn’t trust myself with high current either ( i think ) tbh i hadn’t done the math to determine what the current would be. I literally just saw your comment about that and ran to grab an ohmmeter. It says 1.2 ohm resistance from the bulb, so at 2.4 volt I should be dealing with just 2 ampere of current… ignoring any resistance added by the springs or anything. should be fine (I think, honestly do not remember :slight_smile:

What is the fire risk, exactly? Is there a point where using the body of the torch as part of the circuit not safe anymore? Or is it a risk of arcing in the switch? I don’t have any of those super bright lights, (I think 1200 lum Olight baton 3 is highest) but as far as I have noticed they all use the body as part of the circuit. Well, except the ones with plastic bodies. If I were using regular lithium batteries, that alone would make me not want to build my own switch, but I’m using “custom” 2.4v with protections and even charging built in, so I’m less concerned.

I appreciate the offer for info regarding working copper. I love the look of copper and bronze and would like to do more work with it in the future. I’m trying to do this quickly, so I am trying to do it simply. (plus, I have no idea what I’m doing :slight_smile: I’m currently rethinking the switch slightly, but the plan is to try to complete the project tomorrow. So far I have basically been experimenting with the design and tools and et cetera. If I get to own my day tomorrow, I should have it done. I have other projects that need my attention and must move on soon.

I do plan to continue working on projects like this though! I’m enjoying the learning. Whilst cleaning and reorganizing my tools and things, I found some leds, cob lights, a laser I think, and etc. Heatsinks from old computers, films from lcd monitors, (omg the aluminum case from an old powermac!) and just a bunch of old scrap parts and junk. I think it’s time to put them in play or throw them away.

So, progress has been slow. I’ve got no idea what I’m doing :slight_smile:

I’ve tried to redesign the switch several times. Realized that I was overcomplicating it from the beginning. Settled on final design.

I managed to solder a spring into the end cap. It’s sloppy and kinda off center. I don’t have soldering tools. Happened to find a bit of old solder wire, put end cap on old kitchen hotplate (backup for gas stove), put few bits of solder and waited for it to melt, stuck spring assembly (failed redesign of switch button :slight_smile: ) into solder pool, tried to remove with pliers while holding spring in place with tweezers, slipped a little. But, it ought to work.

Experimented with stealing Asian8640’s “screw to hold the cap” on, in case I decide to go that route. No idea how else I would’ve done it anyway. Found a “copper” screw (it’s ferrous, but copper colored) that would look good enough that I’d probably just leave it sticking out so I can thread it through both the cap and tube. Drilled hole (forget size) and “force threaded” the screw. Tricky bit, and I’ll experiment with it tomorrow, would be that in order to align the threads (if I screw through both layers of copper) I would have to force the screw into both at the same time. It forced some copper to raise from the pipe when I did that, and some to bulge on inside, so it may make the two parts hard to separate so that I can file down those bulges. But I found some spare caps so I can risk one trying it.

Made clamp for pipe so I can try to cut straight with hacksaw instead of using tube cutter. Maybe. Harder to cut, but should be easier to clean up?

To do list “for tomorrow”, hopefully:

  1. Rework the wooden bulb cradle - I think less of it should stick out from tube, also it’s face doesn’t feel like it fits inside cap just right. Maybe add some kind of spacer (rubber or silicone?) to back bulb back into cap, currently protrudes slightly.
  2. Once that is done, need to drill/cut new slot for switch (and it’s spring) opposite from old one. This wood is pretty hard, I think it can take the weakening from having two slots cut in it. Besides, once it’s all together it will be held between cap and tube.
    2.5. I still need to cut switch part to correct length! It can’t stick out as much as I wanted it to because it has to press in far enough to let the cap slide over it, with spring in place, without doing any damage.
  3. Assemble the head. It should hold together pretty well on it’s own. Spring holds switch in place and switch holds rest of head together? We shall see.
  4. Cut and clean up (maybe just a little, has nice patina already on) tube for battery.
  5. Test that light functions.
  6. If necessary, apply screw to hold tail cap on. Der, and head cap, probably! Wait, switch may hold head on…IDK we shall see.


I used a battery from my Olight i5R, an incandescent bulb from that broken, disposable penlight, and miscellaneous scrap and garbage! In the end, budget was $0! I did buy a can of satin clear enamel to protect the patina, but I decided not to actually use it.

Here are the parts of the finished light.

The wooden bulb cradle modified for the new design.

The switch ended up having to be way smaller than I originally expected.

The end cap with battery spring soldered in (more on that in write -up below)

Head-end of tube with slots for switch and spring.

Spacer I ended up needing to hold wooden bulb cradle snug in tube (more detail in write-up below)

The spacer (silicone?) to pull the bulb back up inside the head. Spacer above was made from scrap left from this.

Switch with spring in.

Switch/spring positioned with tube and cradle.

Ok, on with the write up. —>
So, the final format is actually pretty similar to what I hoped would work in the beginning. That first switch design was giving me problems. I tried to redesign it for days. The most interesting/difficult one… I took some very thick copper wire, drilled small hole down into it (making it like a tube, just not all the way through) then crammed some pretty thick copper wire in that hole. Made a good shape for a switch, (kinda like [===, if [ part were a bit longer ) but I couldn’t find space to “spring it” and “retain it.” Whilst trying to figure that out, I suddenly realized what was wrong with my original switch… the spring served the dual purpose of springing it up off the bulb, and holding it in place! I was overcomplicating it. In fact, it should hold the entire head assembled and attached to the tube! So simple!

While I was still puzzling over the switch, I was also puzzling over how I was going to get a spring in the battery cap. I don’t have soldering tools, so I planned on taking a conical type battery spring salvaged from an old remote control and shaping its “tail” to fit in the cap, then I was going to cut thin sliver of tube and try to hold in place with that. But, it didn’t have enough “tail” to make that happen. However, while I was digging around looking for other possibilities I found some old silver solder. I made a “spring assembly” by taking a cylindrical spring (salvaged from a 3xAAA battery cradle from an old headlamp, if I remember correctly where it came from) and forcing it over the very thick coper wire on that failed switch experiment. Then, I cut off the thinner wire that stuck out. I placed the copper tube cap on a kitchen hotplate (backup for the NG stove) and put a few snips of solder into it. Once the solder melted, I used tweezers to place spring assembly into solder pool. A mistake was made here as I tried to grab cap with pliers and remove from hotplate while holding spring assembly in place with tweezers. In retrospect, I probably should have just let go of spring assembly and moved whole thing away with pliers. Spring is not in center now, but it still works.

Once the battery spring and switch problems were solved, it was basically just a tube with a battery. That did not deter me from making more mistakes! I measured from where the wooden cradle meets the tube down to the +pos end of the bulb in the cradle. I pushed the battery down in the cap to see how far in it should go…. I added the “bulb space” and “battery space” and cut tube at that length. I did not add any tube to go down into the cap! Luckily, I discovered my error before cutting slots in tube for switch and spring. So, I cut new tube about 10mm longer.

I found some random rubbery, think it was silicone, piece in a bag of scrap parts. I think it came from a printer. It was a square-ish thin thing, with a row of small holes on one side and a row of slots on the opposite side. I used a paper hole punch to cut a hole in the center and nail clippers to trim it to fit the size of the wood. Oh, BTW, I think the spring I used for the switch came from the same printer (or whatever) as the silicone piece. They were in same bag of parts.

Now, I cut slot for switch with head parts assembled (minus bulb, of course) using cut-off wheel on Dremel. Even though I used an old worn down wheel, the circumference of the wheel means it basically just cut out the center and guided me in using the diamond coated bits to actually grind out the slot This is where I discovered that my wooden bulb cradle was not snug in this pipe (I had been working with it in a short piece of scrap up ’til now, which was apparently warped or something) because as I tried to grind the slot longer in all three layers (cap, tube, wood) the wood kept sliding around! So I took it out and just cut cap and tube slots ’til I was happy with width.

Ground width of switch piece down to fit in that slot, THEN cut slot in wood to match cap, tube, and switch.

Cut slot for spring in tube. Cut angles in wood to allow spring somewhere to flex.

Put spring through hole in switch and marked where it met the wood (cut here and it won’t stick out) and where it met the cap (leave a little so it does stick out) Clamped and cut and burned and dropped and found and ground and polished and done. :slight_smile:

I clamped the switch part between plywood scraps to cut or grind it multiple times. It burns the plywood when to copper gets hot. Then it gets loose. I lost my switch 3 times, I think, and had to start over again! If it gets hot enough to smell like burning wood, I need to stop and move it to fresh, unburned part of wood scraps.

I am sure I am missing some of the things I tried and mistakes I made, but this is the bulk of what ultimately went into the final product.

Tools used:

These did most of the cutting and shaping of both the wood and the copper.

These held things when my hands couldn’t. The purple marker fit perfect down inside the space the bulb goes, so it held the wood while I shaped it! The plywood with hole and slot was used to clamp the tube so I could try to cut it straight. (not pictured: 5/8” spade bit used to drill hole and miter saw used to cut slot, and scrap of cedar board placed under plywood while drilling, oh and other scrap of plywood used as space so miter saw cut where I wanted it to) Not sure it was used on the final tube, but I used it on the tube that was too short. Tape held cap and tube together while switch slot was cut.

These tools were used to mark various things at various times. The wooden handle things are an old drypoint needle and scraper. Used for making intaglio prints on copper plates. Mechanical pencil. That same purple marker from before. I used the caliper type thing (honestly don’t know what it’s called) to mark an even line around wooden part to see how much to shorten the thicker part that sticks out of the tube.

Other contributors: Paper hole punch, random solder I found in a drawer in the back, nail clippers, and what was left of that random bit of silicone or whatever it is. Oh and my Olight i5R cu which was often lighting my way around finding tools or trying to find bits I dropped in the leaves out in the yard.

hacksaw and jigsaw (don’t think I used the jigsaw, but it was around so…)

Cordless drill and drill bits. Don’t think I ended up using them on the final product used to drill out wooden bulb cradle/insulator and hole in pipe cap covering same, but and were used in some of the experiments. Same with screwdriver. That light was around and may have helped, I don’t remember :slight_smile:

Oh, just for fun:

The screw that I was going to use to hold battery cap on (friction seems to be working just fine) It did force-thread just fine. Was a little hard to separate cap from tube, but it did separate without any damage.

And, finally,


IT’S ALIVE!!! (insert your own maniacal laughter here)

Thanks folks! Now I’ve got 2 new addictions! (both collecting AND building/modding lights)

Saw mtndon’s little wooden lantern and now I want to build some lantern type lights out of these cheap-o headlamps I have laying around, but never use because they aren’t good! I’ve found some old pyrex tubes that were replacements for an old vape tank I don’t have anymore… we’ll see where it goes.

I made short video but I not posting it correctly :slight_smile:

just click here if you wanna see it, i guess

This thing?

I would call that a marking compass. If the lead was replaced with a steel point it would be a pair of dividers

Thank you! Dividers is what I wanted to call it. But I couldn’t find the word :slight_smile:

It was part of a set with a compass. The lead holder from the compass (no screw to hold it at specific angle) and the larger metal spike that was in this are interchangeable.

Congrats on completing your light before the deadline! I will hold up my end of the bargain.

No obligation. Just meant I wouldn’t allow myself to take you up on that if I didn’t finish my build :stuck_out_tongue:

For now, I’ve disassembled it to polish up the insides of the caps and ends of tube covered by them (connection was fine, I should’ve let it alone), and mangled the spring trying to put it back together! Might wait until a.m. (hoping I’ll be less butterfingers), but I’m going to get a new spring cut and get it working again!

Burned my thumb sloppily holding wires to end of 21700 to test an LED last night! Wiggled, arced, burned. Maybe why I’m having trouble reassembling that light now?

Guess I need to get cheap single cell charger (ooh, or maybe one of those that magnetically clips on ends of battery) to mod for testing things. :stuck_out_tongue:

Phew! Fixed.

Ended up running a length of upholstery thread through the spring and the cap at the light end to help hold the spring in place while I assembled it. Spring was pressing too far into the angled slots (for flexing) and folding in to the point it couldn’t come back up into the space where it supposed to live when button isn’t being pressed. Holding the thread tight helped prevent it from over-folding and/or helped pull it back up into position afterward if it did.

Patina showed some file marks so I polished it up with a “double crossing helix” pattern. Pardon my twitchy thumb, been up all night at hospital. He said as if it were somehow related. :smiley: