Super-light, strong material options for neck-carry lights

Just talking today about my wish for materials which were lighter, possibly even lighter than aluminum, but didn't need a coating and were plenty strong too, made me decide to open conversation, and hopefully attract attention of makers to bring us some new tiny lights, which don't hit you in the face so hard when moving too quickly with neck carry lights.

For the record, I'm hoping for a 10180 (or slimmer) neck-carry light with either sweepable output or at least three modes, but most importantly super-lightweight, durable and non-coated material.

Just to clarify the intent of this thread a little bit better, not looking for reasons to stick with presently accepted materials, but rather to push the envelope.

Also not looking for reasons why new ideas won't work, but how to make new ideas work.


Lightweight metallic glass is strong as steel

Fibrecore

Entrepreneur Creates World's Lightest, Strongest Steel - In Less Than 10 Seconds

Re: Super-lightweight but strong material options for lights

Aluminum is light enough, strong enough, common enough, cheap enough, and an excellent thermal conductor.

Steel, an ingredient in both Fibercore (link #1) and Flash Bainite (link #2), is even worse than titanium when it comes to thermal conductivity. Zirconium, used to create the alloy for #3 along with titanium, is used as a thermal barrier coating due to its low conductivity, so you can forget about that, as well.

Carbon fiber is lighter and stronger than steel, but there's only a handful of flashlights made out of them, and none of them are high powered because they can't dissipate the heat fast enough.

Small aluminum flashlights get hot very fast even at relatively low outputs. A tiny light that is made out of materials that doesn't allow for decent heat dissipation, and powered by high voltage lithium cells for high output... That's just asking for trouble.

Re: Super-lightweight but strong material options for lights

You're obviously not into the spirit of the thread and I'm going to ask that you go find some other threads if naysaying is all you have to contribute.

No mention was made of output levels and the important thing here is to explore what possibilities exist, which would naturally be forced to stay within the constraints of their given materials.

Look at the title once again and you'll notice that there are only two particulars that I'm after here, light-weight, and strength. Price, output levels and everything else is only of secondary concern to my curiosity here.

Re: Super-lightweight but strong material options for lights

All I can think of is carbon fiber tube, the issue is that it's going to be bulkier than aluminum for the same strength, and unless you get real creative so you can use the carbon fibers as conductors you'll need a metal strip for the other battery terminal, adding to size and complexity. Ultra thin, hardenable stainless steel would be a candidate. no way to thread something that thin so it would need some other kind of fastening method for the head, maybe bayonet fit. Unhardenable stainless like the 300 series stuff won't work, as thin as we're talking to get a noticable size/weight advantage over aluminum unhardened steel wouldn't be stiff enough to resist damage.

Re: Super-lightweight but strong material options for lights

The TACM lights were made out of Delrin, and were really strong and lightweight. TACM is long gone, but a google search has decent info about them.

Re: Super-lightweight but strong material options for lights

kaichu dento said:

You're obviously not into the spirit of the thread and I'm going to ask that you go find some other threads if naysaying is all you have to contribute.

No mention was made of output levels and the important thing here is to explore what possibilities exist, which would naturally be forced to stay within the constraints of their given materials.

Look at the title once again and you'll notice that there are only two particulars that I'm after here, light-weight, and strength. Price, output levels and everything else is only of secondary concern to my curiosity here.

Click to expand...

If you read the first line of my post, you'd know what I mentioned is completely relevant to the topic. Not to mention that I have provided another example of "super-lightweight but strong material" that is used in flashlights at the bottom.

Re: Super-lightweight but strong material options for lights

You can get specialty carbon fiber that greatly exceeds the thermal conductivity of aluminum, so I'm not sure why you think the heat issue rules it out.

The main reason not to use carbon fiber for most applications is cost. It is also very hard to make good carbon fiber consistently, and since it shatters into sharp edges like glass, that is particularly problematic.

As the technology advances I think it will be a good bet, it is still in infancy when compared to steel or aluminum manufacturing.

Re: Super-lightweight but strong material options for lights

enomosiki said:

If you read the first line of my post, you'd know what I mentioned is completely relevant to the topic. Not to mention that I have provided another example of "super-lightweight but strong material" that is used in flashlights at the bottom.

Click to expand...

In response to your confusion, partially enabled by my lack of clarity, I've updated the OP.
Your first line simply supports the continued view of aluminum as superior and the next three short paragraphs go directly against the focus of this thread by looking for reasons to say "why not", when the responses that are needed are "how to overcome the difficulties" regarding other materials.

Maybe you hoped to play devil's advocate, and if that's the case, please come up with some suggestions for how to make other materials viable.

thedoc007 said:

You can get specialty carbon fiber that greatly exceeds the thermal conductivity of aluminum, so I'm not sure why you think the heat issue rules it out.

The main reason not to use carbon fiber for most applications is cost. It is also very hard to make good carbon fiber consistently, and since it shatters into sharp edges like glass, that is particularly problematic.

As the technology advances I think it will be a good bet, it is still in infancy when compared to steel or aluminum manufacturing.

Click to expand...

I really like the idea of carbon fiber, particularly for a light that might only hold a 10180 where the likelihood of being crushed is at least partially minimized and while much of the focus on lights recently has been on ever higher levels of output, a three level light that offered 1>10>70 lumens running a Nichia 219 with 10180 shouldn't be running into heat problems, and should also have some pretty reasonable runtimes.

Re: Super-lightweight but strong material options for lights

Anyone mention Magnesium, Scandium, boron, most plastics,even wood is quite light and strong at this scale.

Re: Super-lightweight but strong material options for lights

The metallic glass mentioned in the OP is made from titanium and zirconium. Zirconium, as in synthetic diamond. Diamond conducts heat more than 4x better than silver. I'm not sure how much thermal conductivity is lost to the titanium and the crystalline structure. The point though, is that this a zirconium based glass rather than a silicon based glass, so the thermal properties may be much different.

Re: Super-lightweight but strong material options for lights

dano said:

The TACM lights were made out of Delrin, and were really strong and lightweight.

Click to expand...

I'd forgotten about the viability of Delrin and it's actually pretty practical, if not exotic. With its lack of heat transfer properties, I wounder how much output it could handle, because if an all Delrin light could handle up 50-80 lumens, I think it could make a pretty decent neck carry light.

Juggernaut said:

Anyone mention Magnesium, Scandium, boron, most plastics,even wood is quite light and strong at this scale.

Click to expand...

Magnesium is the only one I'd thought of here, but have also wondered about bamboo.

Having just barely even heard of scandium and not thought of boron as anything other than an alloy, would they be practical?

scsmith said:

The metallic glass mentioned in the OP is made from titanium and zirconium. Zirconium, as in synthetic diamond. Diamond conducts heat more than 4x better than silver. I'm not sure how much thermal conductivity is lost to the titanium and the crystalline structure. The point though, is that this a zirconium based glass rather than a silicon based glass, so the thermal properties may be much different.

Click to expand...

Definitely sounds interesting still, especially since I don't think that all lights need to have envelope pushing output levels to be practical every day lights.

These three posts are the type I was hoping to see as I'm really hopeful of seeing more options come into play in the future.

Re: Super-lightweight but strong material options for lights

Scandium would make for a very high priced flashlight. S&W adds only very small amounts of it to their Titanium alloy for increased toughness. The resulting Sc-Ti alloy allows S&W to make very light revolver frames that can handle the pressure and recoil of magnum pistol rounds. Titanium is already quite resistant to abrasion, and much harder to machine than steel or aluminum. Adding Sc to the alloy makes it even more abrasion resistant. Even though S&W frames are shaped primarily by forging and then finish machined, I've been told by sources formerly inside the company that the Ti-Sc alloy is still extremely hard on tooling.

This would result in flashlights made from a Scandium alloy being very expensive. The alloy would either chew up tooling when boring out the battery tubes, or the tubes would have to be made on a rotary cold hammer forge much like military grade rifles bbls. are made. However, the toughness of the alloy would allow for ultra thin bodies, and much thinner thread sections than are currently possible with Aluminum bodies. If the goal is thin and light weight over maximum output, and cost is not an issue, then a Scandium alloy could be quite interesting.

Given how light Sc-Ti alloys are to start with, and how thinly they could be machined, I'd be very curious to see what could be done with composite construction. Namely, I think a brass or copper liner and cladding for thermal conductivity with a thin Sc core for strength could make for a lightweight light that would still have excellent thermal management. Alternately, perhaps just a copper or brass lined body that mates to a copper or brass clad finned Sc head would also work quite well. I'd go ahead and plate or clad the tailcap in brass or copper to give symmetry to the two tone look.

Re: Super-lightweight but strong material options for lights

Whew, we're attempting to cover a lot here. A few thoughts (by no means exclusive, just off the top of my head),

• Zirconium metal - expensive, very difficult to fabricate. Zirconia - ZrO2 - clear crystalline, ceramic, very very hard. Not that great of a thermal conductor due to tightly bound electrons.
• Scandium - very very expensive. S&W has used "Scandium" in a few of their revolver lines, but it's actually an alloy of ~98-99% aluminum & ~1-2% scandium IIRC. It added quite a bit to the price tag. An excellent structural alloy but although I don't know the thermal conductivity, it should be substantialy poorer than aluminum due to how effectively the Sc strengthens the Al.
• Magnesium - comparable strength-to-weight ratio to aluminum, but due to its HCP crystal structure it tends to fail via fracture rather than bending. Can take less alloying due to the same limitation, which is why we don't see that many 'high strength' Mg alloys - they are just too brittle.
• Carbon fiber - good thermal conductivity in the X direction (or X-Y direction for weave), but very poor in the Z direction - so it's a difficult row-to-hoe vis. the composite.

Folks talk about the thermal conductivity of diamond, but neglect to point out that whenever there will be a metal-diamond interface, the primary thermal carrier in metals (i.e. electrons) transfer heat very poorly to the primary thermal carrier in diamond (i.e. phonons / lattice vibrations, the very strong & stiff atomic bonding) and vice versa. I've done lab research on this - the thermal conductivity of 50 Cu / 50 Diamond composite has been measured to be considerably worse than commonly available copper alloys.

I think that a lot of promise might be in polymers due to the myriad possibilities in engineering specific properties as well as combining them i.e. fiber & matrix - therefore attaining decent thermal properties, although their main advantage will be light weight rather than being able to handle a lot of heat.

I'll stroll through the lab after lunch and weigh my AAA light against the AAA battery inside it. The battery is definitely a limitation with regards to how light we can get these lights.

We do have a flashlight related materials subforum and I'm inclined to move this thread to there - there are numerous metals experts there, that's for sure.

Edit: lol, took too long to type, some Sc info already supplied in the post above. Is it Sc-Al or Sc-Ti though? I was under the impression that the S&W revolvers in question used Ti parts combined with the Sc-Al frames rather than Sc-Ti alloy throughout? Goodness, the already poor thermal conductivity of Ti would be decreased further with Sc though. At least aluminum has a good leg up to begin with.

Re: Super-lightweight but strong material options for lights

scsmith said:

...would result in flashlights made from a Scandium alloy being very expensive. The alloy would either chew up tooling when boring out the battery tubes, or the tubes would have to be made on a rotary cold hammer forge much like military grade rifles bbls. are made. However, the toughness of the alloy would allow for ultra thin bodies, and much thinner thread sections than are currently possible with Aluminum bodies. If the goal is thin and light weight over maximum output, and cost is not an issue, then a Scandium alloy could be quite interesting.

Click to expand...

At first I started to wonder if the only benefit would be added expense, since we already have titanium, but if the addition of the alloy would allow the walls to be notably thinner then it might be an interesting possibility.

Given how light Sc-Ti alloys are to start with, and how thinly they could be machined, I'd be very curious to see what could be done with composite construction. Namely, I think a brass or copper liner and cladding for thermal conductivity with a thin Sc core for strength could make for a lightweight light that would still have excellent thermal management. Alternately, perhaps just a copper or brass lined body that mates to a copper or brass clad finned Sc head would also work quite well. I'd go ahead and plate or clad the tailcap in brass or copper to give symmetry to the two tone look.

Click to expand...

Sounds very expensive but I like the way you think, and the cladding/liner approach brings a whole additional set of options.

Kestrel said:

Whew, we're attempting to cover a lot here. A few thoughts (by no means exclusive, just off the top of my head),

• Zirconium metal - expensive, very difficult to fabricate. Zirconia - ZrO2 - clear crystalline, ceramic, very very hard. Not that great of a thermal conductor due to tightly bound electrons.
• Scandium - very very expensive. S&W has used "Scandium" in a few of their revolver lines, but it's actually an alloy of ~98-99% aluminum & ~1-2% scandium IIRC. It added quite a bit to the price tag. An excellent structural alloy but although I don't know the thermal conductivity, it should be substantially poorer than aluminum due to how effectively the Sc strengthens the Al.
• Magnesium - comparable strength-to-weight ratio to aluminum, but due to its HCP crystal structure it tends to fail via fracture rather than bending. Can take less alloying due to the same limitation, which is why we don't see that many 'high strength' Mg alloys - they are just too brittle.
• Carbon fiber - good thermal conductivity in the X direction (or X-Y direction for weave), but very poor in the Z direction - so it's a difficult row-to-hoe vis. the composite.

Folks talk about the thermal conductivity of diamond, but neglect to point out that whenever there will be a metal-diamond interface, the primary thermal carrier in metals (i.e. electrons) transfer heat very poorly to the primary thermal carrier in diamond (i.e. phonons / lattice vibrations, the very strong & stiff atomic bonding) and vice versa. I've done lab research on this - the thermal conductivity of 50 Cu / 50 Diamond composite has been measured to be considerably worse than commonly available copper alloys.

I think that a lot of promise might be in polymers due to the myriad possibilities in engineering specific properties as well as combining them i.e. fiber & matrix - therefore attaining decent thermal properties, although their main advantage will be light weight rather than being able to handle a lot of heat.

I'll stroll through the lab after lunch and weigh my AAA light against the AAA battery inside it. The battery is definitely a limitation with regards to how light we can get these lights.

We do have a flashlight related materials subforum and I'm inclined to move this thread to there - there are numerous metals experts there, that's for sure.

Edit: lol, took too long to type, some Sc info already supplied in the post above. Is it Sc-Al or Sc-Ti though? I was under the impression that the S&W revolvers in question used Ti parts combined with the Sc-Al frames rather than Sc-Ti alloy throughout? Goodness, the already poor thermal conductivity of Ti would be decreased further with Sc though. At least aluminum has a good leg up to begin with.

Click to expand...

The thread has taken a strong turn towards conversation that I'm only capable of acting as an observer to, but this is also what I'd been hoping for, particularly due to the positive direction taken.

Ironic if the light becomes lighter than the power source, but then we already have some incredibly lightweight AAA lights in aluminum that already meet that, including the Arc-AAA, but it's still the overall weight that we're trying to reduce, making the effort still worthwhile.

I thought the niche thrust of this thread might make it worthy of a separate slot here, but if you think it needs to be moved then so be it.

By the way, haven't seen you here in a while and I appreciate your additional content to the thread.

Re: Super-lightweight but strong material options for lights

Carbon nanofoam.

Lighter and more conductive than all the other options.

Re: Super-lightweight but strong material options for lights

kaichu dento said:

Juggernaut said:

Anyone mention Magnesium, Scandium, boron, most plastics,even wood is quite light and strong at this scale.

Click to expand...

Magnesium is the only one I'd thought of here, but have also wondered about bamboo.

Click to expand...

My engagement ring is self-made stabilized wood and I have had some thoughts about making other things (like a flashlight), too. It wouldn't be superior to metals in strength though, and it certainly would lack in heat conductance.

I guess that heat conducting plastics would be good materials for your application. They can be very cheap too, some kinds of heat conducting plastics are used in cheap led lightbulbs (cutting edge materials are more expensive of course). Since neck carry lights don't need to be very crush proof, the materials could also be thin. The core of a little 10180 light could probably weight less than a gram.

Re: Super-lightweight but strong material options for lights

TEEJ said:

Carbon nanofoam.

Lighter and more conductive than all the other options.

Click to expand...

If it's practical then I'm interested.

Esko said:

My engagement ring is self-made stabilized wood and I have had some thoughts about making other things (like a flashlight), too. It wouldn't be superior to metals in strength though, and it certainly would lack in heat conductance.

I guess that heat conducting plastics would be good materials for your application. They can be very cheap too, some kinds of heat conducting plastics are used in cheap led lightbulbs (cutting edge materials are more expensive of course). Since neck carry lights don't need to be very crush proof, the materials could also be thin. The core of a little 10180 light could probably weight less than a gram.

Click to expand...

Both ideas sound to be light and strong enough for neck carry lights and some woods could be very interesting, possibly with the head alone, or both the head and tail made of metal for additional heatsink capacity and or durability concerns, as Scsmith mentioned.

Re: Super-lightweight but strong material options for lights

kaichu dento said:

The thread has taken a strong turn towards conversation that I'm only capable of acting as an observer to, but this is also what I'd been hoping for, particularly due to the positive direction taken.

Ironic if the light becomes lighter than the power source, but then we already have some incredibly lightweight AAA lights in aluminum that already meet that, including the Arc-AAA, but it's still the overall weight that we're trying to reduce, making the effort still worthwhile.

I thought the niche thrust of this thread might make it worthy of a separate slot here, but if you think it needs to be moved then so be it.

By the way, haven't seen you here in a while and I appreciate your additional content to the thread.

Click to expand...

Thanks for the :wave:, I confess that I haven't been posting much recently - we're still approaching June 21/22, so flashlights haven't been as interesting as other pursuits perhaps.

Out of curiosity, I just weighed my Fenix LD01/Streamlight MS combo:

• Total weight: 27.45 g
• Weight of empty light: 15.31 g, 56% of total
• Weight of Eneloop AAA: 12.14 g, 44% of the total

So we can fight only ~1/2 of the total mass with material upgrades for the flashlight body. And I imagine that this proportion is even worse with AA lights - we're adding quite a bit of mass with the larger cell, but an AA body adds essentially only greater circumference and a bit of length.

Which begs the question: What about using the cell itself as a heat path away from the emitter module? We don't have to worry about this with an aluminum body, however a lighter but 'conductivity-challenged' body material could be assisted by a design minimizing the thermal bottleneck between the emitter module and the cell, going all the way to a rear metal tailswitch perhaps? :thinking:

And now we're even getting materials selection back to fundamental flashlight design issues, permitting this thread to still live in /General/ maybe?

Re: Super-lightweight but strong material options for lights

From what I understand, real diamonds are fantastic conductors. Fake are not. Might be a aramid/carbonfiber mix. Aramid is stronger and lighter (and more expensive) than carbon fiber, with metallic threads woven in, can also be conductive. As the epoxy used is clear, that could form the lens as well.

Re: Super-lightweight but strong material options for lights

Vortus said:

From what I understand, real diamonds are fantastic conductors. Fake are not.

Click to expand...

In Thomas Pynchon's book "Gravity's Rainbow," he has a black-market jewel smuggler testing alleged diamonds by seeing how "cold" they feel, i.e. how well they conduct heat away from the skin. Diamonds conduct, fakes do not.

"Glass is a reluctant vampire," says the smuggler, and that line stuck in my head since 1973.