[marozie]

So, the nail polish actually kind of works. The only thing is that because it shrinks so much you kind of have to make the mold like an inverted candle, layer by layer. You fill the mold with nail polish, it shrinks about 50%, fill it up again, shrinks, fill it up again, etc. Probably the best way to do it would be to not let it completely dry in between refills so that the layers completely adhere to one another and so that you don't get air pockets that develop during shrinkage. It certainly isn't the easiest way to make a mold but the proof of concept is there.

 

[marozie]

Reply from Henkel/Loctite:

"This product is available through Loctite industrial distributors. However, it is also a special order item meaning we need to manufacture the product once an order is placed. To find your local distributor where you can place an order, please visit this link Distributor - Henkel. Please be aware that there may be a minimim order quanity on special order items."

 

[marozie]

I've been in communication with Tarek (SilverCans) and Guiseppe about a few things and just want to post what we've talked about for the benefit of everyone:

The important points are: 1) Making actual shells might not be very practical for a DIYer, although I'd like to try out Drew's tumbling method. If someone could get their hands on one of the Loctite UV cure resins and an appropriately powerful UV lamp making shells would be a piece of cake because the UV resins cure in something like 15-25 seconds upon UV exposure. 2) Loctite and Egger seem to be the primary suppliers of the products used to make hearing aids and IEMs by commercial manufacturers. 3) Even these products can produce allergic reactions so there are no guarantees, but Loctite alone makes about a dozen different kinds of resins -- hard silicones, acrylics, polymers that come in different levels of hardness/rigidity -- so there are actually tons of options (once you've infiltrated a distributor). 4) I looked at the Warner Tech Care website and while they do require you to set up an account (and I don't know what that involves specifically) they don't say that they won't sell retail as most distributors do. Warner sells literally anything and everything you could ever want or need for making IEMs (minus the actual electronics), it's a DIY IEM builder's goldmine.

 

[marozie]

I signed up for an account with Warner Tech Care, waiting for it to be activated before I can enter the online shop. Oh man, these materials would make this process SO much easier. So... the way you're supposed to do it is you take this little hollow, clear cylinder called an investment form or cuff (Guiseppe had them in one of his photos) and fill it with a UV transparent silicone into which you place the impression of the ear canal. The mold that this produced is called an investment, or investment casting. The silicone used is a two part RTV. You can also use a material called hydrocolloid, which appears to be one part so I guess it just cures with air contact. Once you have the transparent investment (the mold) you coat the inside with a UV curable acrylic. These come in different shear strengths, colors (can be optically clear or tinted), viscosities, and different levels of softness/hardness. Once you've coated the inside of the investement with the acrylic you either use a handheld UV light (which they sell, and look basically like LED flashlights with special LEDs that are tuned to emit a lot of UV, I assume) or (if you had one) place it in a UV light chamber. These compounds cure in something like 30 seconds of UV exposure, and because it cures so quickly the result is an evenly distributed wall thickness. That's how you make the shell. Then there are all sorts of adhesives, some of which are also UV curable, that you can use to install the parts. You would then have to fashion some kind of "faceplate" and either screw it on with tiny little jewelers screws or they also make faceplate adhesives. The final step is to seal the acrylic shell with a UV curable lacquer which gives it a hard, polished-looking surface. There are even lacquers that are hypo-allergenic, and some that are soft. I referenced Westone offering a shell material that becomes softer with body heat -- they sell that too! It's called Thermosoft and is made by Dreve Materials. Assuming my account gets activated I'm going to buy one of the laquers to coat my IEMs (I have doubts about the durability of the nail polish, it already appears to be cracking). But perhaps when I'm up to it I will make a new set of IEMs from scratch and do it the right way!

UPDATE: OK, so as I suspected, they didn't just automatically activate my account -- they baulked at the fact that I was a retail customer. I spoke to the operations manager, Lee, and explained the situation. He said he had no problem activating my account even though I'm not buying wholesale, they just don't want people trying to buy some of the products (like special hearing impaired telephones and headsets and things) that audiologists would sell retail. So I'm in! And holy crap, are some of these resins expensive! I guess it's to be expected. The Loctite products are around $300 a quart. The Dreve products are relatively cheap though and you can also buy most things in pretty small quantities, like a 20mL syringe worth. The hypo-allergenic Dreve lacquer is $30 for 20mL. Certainly not cheap, but it won't break the bank. Unfortunately, the little handheld UV light sources are like $800 (which I really don't understand), but you can buy UV lightbulbs for growing plans indoors at any greenhouse/nursery. Or just expose it to really strong, direct sunlight. It might take a little longer to cure, but it should work. I'm going to look into buying UV LEDs as well, maybe you could just pop them in an LED flashlight?

 

[SilverCans]

Hi Marozie. I kind of don't understand the face plate part, the company I spoke to the other day mentioned the use of a face plate as well. What I don't get is once the shell is made, I envision it as either one entire closed piece or two halves that can me glued/merged together. So where does the face plate fit into the equation?

Regarding UV Led:
mouser.com has a UV high powered led for $28.80 (part number LZ1-00UA05)
http://www.ledengin.com/products/5wLZ/LZ1-00UA05.pdf
specifically made for "dental curing" and such.

They also have a ton of standard powered uv leds for < $0.70 but I think you'd need to make a circular array of them to get enough light power (I guess its doable but would have to look into how many would be needed).

So far it seems you may continue to make the iem out of what you do now but just coat them in hypo-allergenic Dreve lacquer, is this correct?

 

[marozie]

Quote:

Originally Posted by SilverCans /img/forum/go_quote.gif Hi Marozie. I kind of don't understand the face plate part, the company I spoke to the other day mentioned the use of a face plate as well. What I don't get is once the shell is made, I envision it as either one entire closed piece or two halves that can me glued/merged together. So where does the face plate fit into the equation?

So, if you coat an investment with your acrylic and then cure it you have basically a hollow, open-topped IEM, right? This is the shell. You put everything in the shell, but then the top is still open, so you make a little flat piece that is a lid, more or less. That's the faceplate. Here's a diagram from UE's website:

Quote:

Originally Posted by SilverCans /img/forum/go_quote.gif They also have a ton of standard powered uv leds for < $0.70 but I think you'd need to make a circular array of them to get enough light power (I guess its doable but would have to look into how many would be needed).

I looked on Amazon as well, there's 8 million UV LED flashlights. So, I don't understand why any handheld UV light would cost hundreds or thousands of dollars, other than because that's what they can charge. It's the same thing in the medical device industry. But even if you bought a UV lightbulb, put it in a lamp, and took a cardboard box and lined it with white paper, you'd have a little UV light chamber. It seems pretty easy to get around.

Quote:

Originally Posted by SilverCans /img/forum/go_quote.gif So far it seems you may continue to make the iem out of what you do now but just coat them in hypo-allergenic Dreve lacquer, is this correct?

That's the $64,000 question, at least for me. Since the plastic I used to make the IEMs is urethane and this stuff is acrylic there's no guarantee they are going to stick to each other. I've already had problems with the nail polish flaking off, which is also acrylic.

As an aside, I looked at the MSDS for this stuff. It's polymethyl methacrylate, i.e. plexiglass! It's so well tolerated by the body that it can be used to make medical device implants, and as you alluded to, dentures.

 

[marozie]

So, the LED from Mouser that SilverCans mentioned, from LED Engin, is pretty powerful: ~5V @ 1A putting out 5W. There's also a 10W (17.2V @ 1A!) version. And you can get them in very precise spectral outputs as they're made specifically for curing dental molds (which use the exact same resins as hearing aids/IEMs). I went to Home Depot and found plant light bulbs but they don't give specifications for spectral output. These resins cure precisely at 395nm if I'm not mistaken, so you need something that at least covers a range that includes that frequency, and while plant lights put out UV without some specs it would be a crap shoot. I think buying a UV flashlight on Amazon or something would most likely be useless since most of them seem to be pretty cheap and run on AA or AAA batteries, which means they can't put out much more that a couple hundred mW max, and probably less. And the ones that seem to be higher quality cost >$50; might as well buy the 5W UV LED from Mouser with a 5V AC PS for $30 and make yourself a UV cure light. I'm still thinking bright, direct sunlight is going to do the trick. I ordered the Dreve Fotoplast Lacquer 3 which is the hypo-allergenic stuff. I'll post the results...

 

[Bilavideo]

Exciting stuff!

 

[pdupiano]

Quote:

Originally Posted by marozie /img/forum/go_quote.gif So, the LED from Mouser that SilverCans mentioned, from LED Engin, is pretty powerful: ~5V @ 1A putting out 5W. There's also a 10W (17.2V @ 1A!) version. And you can get them in very precise spectral outputs as they're made specifically for curing dental molds (which use the exact same resins as hearing aids/IEMs). I went to Home Depot and found plant light bulbs but they don't give specifications for spectral output. These resins cure precisely at 395nm if I'm not mistaken, so you need something that at least covers a range that includes that frequency, and while plant lights put out UV without some specs it would be a crap shoot. I think buying a UV flashlight on Amazon or something would most likely be useless since most of them seem to be pretty cheap and run on AA or AAA batteries, which means they can't put out much more that a couple hundred mW max, and probably less. And the ones that seem to be higher quality cost >$50; might as well buy the 5W UV LED from Mouser with a 5V AC PS for $30 and make yourself a UV cure light. I'm still thinking bright, direct sunlight is going to do the trick. I ordered the Dreve Fotoplast Lacquer 3 which is the hypo-allergenic stuff. I'll post the results...

Some possible reasons why medical UV lights are expensive:
1) Specific spectral range:
-While a large range of LEDs may produce 395nm wavelengths, they may also produce a wide range of wave lengths and the over all "power" is decreased (Bandwidth versus intensity I suppose). As you mentioned in your post, direct sunlight would work too (you're guaranteed to get wavelengths in the region you need). But the overall broad band of spectral waves is so great that the amount of actual "power" delivered to the molds may not be enough to cure them (at least in a tolerable amount of time).

2) UV LED lamps/lights may not exactly be UV in that what you buy commercially is in the visible light spectrum but no one really checks if its beyond that. And to be honest I'd be pretty damn worried if UV LED flashlights were actually in the UV range. The melanoma rates in the world would have tripled or doubled by now from kids playing with flashlights.

3) Built in UV protection. Certain medical practitioners do rely on UV lights, I noticed my dentist using something similar the other day to cure a mold (and yes I did ask her if she could take impressions of my ears... she said no). Looking at the device, its made of a single LED, with a shield and a way of concentrating the light to a particular spot.

4) Light concentration/intensity. Along the same lines as a laser, certain optic devices need to be concentrated some how. Based on what I saw at my dentist's office, it doesn't seem like its too complicated, but then again I wasn't exactly allowed to take it apart and tinker with her equipment. I remember that in highschool we were able to make our own electronics projects and half my class chose to make laser pointers because the circuitry was a simple series circuit with an LED and resistor....lazy bastards. But anyway only 2 students built the laser correctly because they bought the proper lens that would concentrate the beam well enough to create a laser pointer, while the rest of the class tried to use lenses they got from flashlights and other random junk they bought at home depot.

Now I'm not saying that this all amounts to several hundred dollars worth of equipment, but what I am suggesting is that you may want to look into the safety aspects of this before moving forward (remember the skin rash issues?). If you really are working in the UV spectrum, take the necessary precautions to prevent getting skin cancer, the last thing we would want, would be skin cancer on your ears.... because then you would have to take new impressions every month due to the changing shape of your ears.

 

[marozie]

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif Some possible reasons why medical UV lights are expensive: 1) Specific spectral range: -While a large range of LEDs may produce 395nm wavelengths, they may also produce a wide range of wave lengths and the over all "power" is decreased (Bandwidth versus intensity I suppose). As you mentioned in your post, direct sunlight would work too (you're guaranteed to get wavelengths in the region you need). But the overall broad band of spectral waves is so great that the amount of actual "power" delivered to the molds may not be enough to cure them (at least in a tolerable amount of time).

Actually, most UV LEDs have a very narrow spectral output from what I've seen, i.e. 390-410nm, 395-405nm, etc. However, cheap UV LEDs that are the equivalent to what you would you would use as a power indicator in a piece of electronics only put out around 100mW or less. These LEDs made for dental curing come in 5W and 10W packages, that's the reason they're so expensive. I would imagine any 5 or 10W LED regardless of its spectral out put would be equally expensive. But then again, to equal the 5W output you'd have to by 20 100mW LEDs, at about $1 a piece you're not saving that much.

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif 2) UV LED lamps/lights may not exactly be UV in that what you buy commercially is in the visible light spectrum but no one really checks if its beyond that. And to be honest I'd be pretty damn worried if UV LED flashlights were actually in the UV range. The melanoma rates in the world would have tripled or doubled by now from kids playing with flashlights.

I believe most people can see light at starting at about 400nm, and UVA, which is 320-400nm, is the least dangerous because it doesn't cause direct DNA damage, unlike UVB (280-320) and UVC (100-280). UVB in sunlight is what gives you a sunburn; UVC in sunlight is mostly filtered out by the atmosphere, and is the most dangerous - it's used for sterilization because it basically destroys DNA. So, yeah, you can actually buy a UV flashlight. Most cheap UV flashlights are probably in the 390-410 range. I say cheap because you can buy more expensive UV lights at 365nm that are made specifically for forensics applications. Apparently things that flouresce under UV light do so the best at 365nm. Not to mention the fact that you can buy UVC sterilization lights for home use. How's that for dangerous?

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif 3) Built in UV protection. Certain medical practitioners do rely on UV lights, I noticed my dentist using something similar the other day to cure a mold (and yes I did ask her if she could take impressions of my ears... she said no). Looking at the device, its made of a single LED, with a shield and a way of concentrating the light to a particular spot.

That sounds like the handheld UV spot curing lights. That's what those 5W and 10W LEDs from LEDENGIN are used for.

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif 4) Light concentration/intensity. Along the same lines as a laser, certain optic devices need to be concentrated some how. Based on what I saw at my dentist's office, it doesn't seem like its too complicated, but then again I wasn't exactly allowed to take it apart and tinker with her equipment. I remember that in highschool we were able to make our own electronics projects and half my class chose to make laser pointers because the circuitry was a simple series circuit with an LED and resistor....lazy bastards. But anyway only 2 students built the laser correctly because they bought the proper lens that would concentrate the beam well enough to create a laser pointer, while the rest of the class tried to use lenses they got from flashlights and other random junk they bought at home depot.

I don't know. I think they're basically just like flashlights with a reflector and a lens.

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif Now I'm not saying that this all amounts to several hundred dollars worth of equipment, but what I am suggesting is that you may want to look into the safety aspects of this before moving forward (remember the skin rash issues?). If you really are working in the UV spectrum, take the necessary precautions to prevent getting skin cancer, the last thing we would want, would be skin cancer on your ears.... because then you would have to take new impressions every month due to the changing shape of your ears.

I'm sticking with my "it's expensive because it can be" argument. If those Loctite Spot Lights are just a flashlight with an LEDENGIN 10W LED (which, granted is like $120 by itself) then there's no reason why it should cost $1000. Other than because they only people buying them are charging them to their company, and buying a piece of necessary equipment for $1000 is something a company isn't going to think twice about because it will end up paying for itself in no time.

No doubt, messing around with a UV light is dangerous. You would certainly need UV safety glasses. But using a UV light a handful of time for 30 seconds at a time is probably going to expose you to as much UVA as you would get standing out in the sun. There are actually OSHA guidelines for how much UV exposure is safe since there are industries where workers are using UV light on a regular basis. We actually got a new fume hood in one of the biology labs at work that has a UV light in it for the purposes of sterilizing it. Maybe I'll just stick my IEMs in there for a couple minutes.

Now this on the other hand...

 

[Bilavideo]

At this point, we've talked about the drivers and the wiring. We've discussed methods and principles behind crossovers. We've even talked about how to make shells the way the pros make them, but without having to resort to expensive injection-mold processes. I wonder, though, whether there's a way to do this using something soft and "plastic" (in the classic sense, like clay) that will harden over time, thus making it easy for the DIYer to make a kitchen-sink shell.

My take on this is a quest to provide the Joe and Jane Lunchbox a means of fabricating a high-quality pair of in-ear monitors but without a lot of specialized gear. It's quite easy to buy the drivers. The same holds true of the cable and solder. We've gone over outlets that provide hearing-aid tubing that delivers the sound. The only thing left is the plastic shell to house the components, act as a locus for stress protection (to prevent wires from being pulled out) and provide a means of sealing the opening of the ear canal for proper isolation and bass containment (without an airtight seal, you can't provide the right air pressure for bass without volumes that risk hearing loss).

If we had a material with the plasticity of a stick of chewing gum, but self-hardening (and without toxicity), we'd have an easy winner in the "easy to do it" category.

 

[marozie]

Yeah, this definitely seems to be the hard part. It seems like there's inherent toxicity with liquid plastics which is mostly due to the chemicals that are used as solvents, or in the case of epoxies the hardener component. The biggest problem is that outside of the medical device industry (and I'll throw hearing aids into that pool; and since companies that make IEMs use hearing aid supplies you could throw them in there as well) there really aren't any industries that have a need to make plastics that are safe for repeated or prolonged skin contact. So therein lies the dilemma; plastics that are readily available (and therefore cheap) aren't necessarily safe (and in most cases there's simply no way of knowing); plastics that have been specifically designed to be safe aren't readily available and are therefore extremely expensive and hard to procure. Another problem I found is that MSDSs don't differentiate between the characteristics of the liquid form and the hardened (or cured) form. Since just about every liquid plastic is toxic every MSDS is going to say that it shouldn't come in contact with skin; even the MSDSs for the UV curable acrylics say "may cause skin irritation," "do not inhale," etc., which we can deduce is referring to the product in the liquid phase because we know that the cured final product is perfectly safe. The easiest thing to do would be to use latex or silicone, or even the two part foam rubbers that are used to make the impressions of your ears in the first place. I'm just skeptical about how well the internals would hold up in such a soft and flexible shell, and the long term durability probably wouldn't be great. On the other hand they would be incredibly comfortable.

 

[buz]

Use a hard plastic inner casing and a soft shell which can be replaced?

 

[marozie]

I was waiting for a nice sunny weekend to try out the UV lacquer, which ended up being today. It worked like a charm. It cured in a matter of minutes in direct sunlight. Unlike the nailpolish, which has a very tacky surface even after it dries which made it at times a bit of a challenge to get the IEMs in my ears, with this stuff on them the slide right in. If you're willing to pay the premium for this stuff it solves a lot of problems with potential toxicity/allergy to your primary plastic substrate; this stuff is even hypo-allergenic.

 

[Lpe_91]

..