New Atomizer Prototype

[Scottes]

You can't just dip the nichrome wire into molten Pyrex - I would think you'd need some space for expansion when the wire heats up.


But.... Why are lightbulbs so big in relation to the filaments that are so small??? Even in a halogen for a mini-mag, the hollow space of the bulb is much larger that the filament. Could this just be a manufacturing limitation?

 

[Bubo]

Obviously, it just spewed from my brain with no thought.. (I have a very poor censoring chip in my head!)

So there needs to be some wire expansion area... Hmmm... I may have access to a 1500 degree kiln - just have to go to the dollar store and get a Pyrex cup, that should be enough glass to last a while! And nicrome... Exploding glass - should be fun!

Okay, seriously though. Assuming that we can melt Pyrex, and dip a coil into it - can anyone think of something that we can "pre-dip" nichrome in that would create an expansion area? Say we pre-dip the nichrome in the magic stuff, let it cool/harden/solidify, then dip it in the molten glass covering everything except the leads. The heat of the glass burns off the magic stuff creating a bubble in the glass for the nichrome to expand in.... Make sense? Any ideas?

 

[Jason365]

Here is a link to quartz tube manufacturer. Thay claim they will build you anything you want. Dont know what its costs though But maybe they will make some samples so you dont have to order 1000 of them. It may be easier than melting pyrex and dipping a coil in to it.8-o

quartz tubes, quartz wafer carriers, crystal growth quartzware, EPI quartzware, quartz plate, quartz window

 

[moktarino]

Hello, first post.

Anywho, I was thinking about this problem, and I was reminded of a time when I made temperature probes out of a thermistor on a wire and a glass pipette. I used a blowtorch to melt the tapered tip of the pipette shut and squashed it a bit onto the tip of the thermistor.

I have in mind an atomizer consisting of a thin-walled boron-glass (pyrex is a brand of boron glass) tubing, perhaps 2mm diameter, containing a coil of nichrome wrapped around a capillary tube with one lead going through the center of the smaller tube. One end of the tube being sealed, the other being sealed around the nichrome's leads that have been soldered on previously.

That would look somewhat like a lightbulb or radial capacitor. Alternately you could make it like the leads axial (coming from each side), depending upon the desired form factor.

I'm designing a DIY nicotine delivery device and am considering this method for the atomizer.

 

[Carlos49]

Wow - definitely 'outside of the box'!


Hey - wait a minute - what if we just dip the Nichrome coil in Pyrex glass?
That takes the air out of the picture, thermal transference is dropped, glass breakage is minimized, preheating is dropped, nickle foam around the heater is gone, bridge is gone, epoxy is gone... Electroplate the Nichrome leads with copper (in a thread somewhere) and the solder is gone too.

Make the glass/nichrome long enough to stick in the cartridge wadding and the only thing left is to figure out how to connect it to a battery.....

Okay... what am I missing - that's too simple....
(Oh yeah - how do you melt Pyrex....)

Sounds like a great Idea!!! Sometime the simple things are staring you right in the face.. I wish I had the equipment to try something like that.
Let me know how it goes !!!

 

[moktarino]

Keep in mind that borosilicate glass softens at 820C (around 1500F). That's softening, not melting. There are a few formulations that soften at lower temperatures (700C/1200F), however, but I don't think it will make that much difference. Anything organic would not be able to survive this, so that leaves out any form of epoxy.

The kind of heat required to melt borosilicate glass to the thinness required for "dipping" is pretty high. I'm not keenly aware of the viscosity/temperature gradients for glass, but if the softening temperature is 820C you could estimate that the "liquid-like" temperature is probably somewhere upwards of 1000C. The melting point for nichrome is 1400C, but you'd need to braze it onto the leads as any solder you might want to use would definitely melt below that temperature.

These temperatures make dipping out of reach for your home hobbyist (myself included). It might be possible to order a small run from a Chinese manufacturer of things like this, but your tooling costs are going to be a bit higher than any individual would want to pay.


You can certainly reach softening temperature with a standard propane torch, though, enough at least to squash the tube.

http ://cgi.ebay.com/350--KIMBLE-1/10-ml-Glass-Serological-Pipettes-Pipets_W0QQitemZ150378905407QQcmdZViewItem#ht_1234wt_1150]350- KIMBLE 1/10 ml Glass Serological Pipettes Pipets - eBay (item 150378905407 end time Nov-07-09 09:54:59 PST)

More later.

 

[roadkilldeluxe]

Pyrex glass will take fast temp changes and smaller wire is actually the opposite way to go. IMHO 36ga NiCr is around 20 ohms per foot. 40ga jumps to whoppin 70ohms per foot.

True, but it takes less amps to get it heated to a specific temperature. Unfortunately, I ordered 32,36,40ga and recieved 26,32,36 instead. So I guess I should just use 36ga to start with? What did you use for your coils?

Basically making it a cartomiser

I too, was thinking along those lines. My only worries were (1) having epoxy directly on the juice and (2) would the legs need to be insulated? I think this could lead to a very compact and clean system, though. I really like the design of the cartomizers.

Perhaps a drop of molten glass on the end to seal it instead? Thermal conductivity of air would take an extra second or two, I would think... but is it negligible? Smaller Christmas light.. Cut it closer to the top as time goes on and practice would make closer tolerances... Perhaps an On/Off switch to turn on a preheater?

I'd love to be able to seal it with glass. Just not sure how or if I have the tools. And the preheater is something I mentioned in an above reply. It might not be too bad... plus, if it's preheated it will result in almost instant vaporization when you hit the 2nd button since everything will be 95% ready.

As for your idea about encasing the coil in glass, i'd love to. In fact, I was looking up glassworking costs yesterday, but it takes about $1000 to get a decent start in glassworking/blowing. The easier way would be to get a tiny glass rod, stick the coil in there, and seal off both sides. Almost as good!

Assuming that we can melt Pyrex, and dip a coil into it - can anyone think of something that we can "pre-dip" nichrome in that would create an expansion area?

Maybe dip a really hot, thick Nichrome coil into glass, let it cool and shrink, hopefully small enough so that you can actually pull it out, and then "snake" a smaller Nichrome coil through. Seal the two holes. But I think this might be too much work.

Anywho, I was thinking about this problem, and I was reminded of a time when I made temperature probes out of a thermistor on a wire and a glass pipette. I used a blowtorch to melt the tapered tip of the pipette shut and squashed it a bit onto the tip of the thermistor.

Excellent, I wonder if I can seal off the glass bulb this way!

I have in mind an atomizer consisting of a thin-walled boron-glass (pyrex is a brand of boron glass) tubing, perhaps 2mm diameter, containing a coil of nichrome wrapped around a capillary tube with one lead going through the center of the smaller tube. One end of the tube being sealed, the other being sealed around the nichrome's leads that have been soldered on previously. [...] I'm designing a DIY nicotine delivery device and am considering this method for the atomizer.

Could you post any diagrams? (I love diagrams) Sounds great, though. How will you be sealing the tubes? I hope this idea (and hopefully some positive results) will help you out in your endeavors, and thanks for the input! Keep us updated with your projects!

 

[Scottbee]

I'll continue to follow this thread with great interest, but I've got to be honest with you.. I'm not personally sure I understand what you're trying to accomplish.

Let's say that you are ultimately successful with getting some nichrome put inside of a glass bulb or coating. And that you are able to figure out how to get the time constant down so that it heats up quickly enough. Then what?

You still need to devise a delivery mechanism for the e-liquid. And I can assure you that you're not going to just stick the bulb directly into the cart material. A quick test with a temperature controlled soldering iron will show you that it's a bit more complicated than that. You need a device that will feed liquid to the heated element in a controlled manner. In the case of the 510, that happens to be a wick that runs from the mesh at the top of the bridge to the nichrome coil. Those that think that the bridge itself or the mesh around it gets hot enough to vaporize the e-liquid are mistaken and don't really understand the complexities of an atomizer. The vaporization happens right at the coil, and no place else.

At best, your method only really helps to reduce the possibility of the nichrome coil getting oxidized.... It doesn't address the feeding of the e-liquid and it doesn't address the problem associated with the vaporization by-products being deposited on the heated surfaces.

I'm not trying to dampen the thinking process at all... just want to make sure that we understand what the end-game is!

 

[roadkilldeluxe]

You still need to devise a delivery mechanism for the e-liquid. And I can assure you that you're not going to just stick the bulb directly into the cart material.

I'll admit I don't yet know how the delivery system will work, but isn't sticking the heating element into the filler exactly how cartomizers function?

[...] it doesn't address the problem associated with the vaporization by-products being deposited on the heated surfaces.

Hopefully this won't be too big of an issue, I think that the glass heating element will be much easier to clean than the traditional coil.

As for what I'm trying to accomplish overall... I guess to see if there's a better, more reliable atomizer (or fully reusable cartomizer?) that can be made. It seems like the high maintenance and somewhat low reliability of current ecigs turn people off of vaping. I'm hoping to get the ball rolling on a new design that will make ecigs a stronger competitor to analogs. Charging and refilling will always be an issue, but worrying about flooding/drying out/burning out/primer/buying replacements online/cleaning every night/etc doesn't have to be. (I hope )

I hope to one day not have to explain to everyone exactly how to use it, the "proper way" to inhale, etc. My friends are super interested in vaping but I can't imagine any of them making it past a few days once they realize how much harder it is than simply carrying a BIC and buying a pack at any gas station when you're out.

Keep the critiques and ideas coming! I'd rather figure stuff out and deal with obstacles sooner than later! Thanks everyone!

 

[Scottbee]

I'll admit I don't yet know how the delivery system will work, but isn't sticking the heating element into the filler exactly how cartomizers function?

Not really. A KR808D-1 cartomizer certainly does have an exposed heating element, but it is wrapped in a layer of material that has a different wicking characteristic than the poly cart filler. That layer acts as a barrier between the poly filler and the coil... controlling the rate of liquid flow. And frankly, I don't think it works all that well.

I believe that the inside of a GreenCig cartomizer is more "traditional"... with a coil, a reservoir, and a wick that carries the liquid from the reservoir to the coil.

P.S. I'm right there with you on the need to simplify the use of PV's. I was hoping the cartomizer approach would get us there.. and maybe it's close. But I won't give up my 510 for a KR808D-1. The vapor production just isn't there. I'm hoping/thinking that we're just one or two generations away from something that we can readily recommend to the "unwashed".

 

[Bubo]

I was messing around this evening with glass (artsy fartsy stuff) and the instructor couldn't come up with any reason for this not to work... Of course, she didn't understand the full aspect of what we are doing - but she didn't see any issues with sticking metal in glass - she says that she does it all the time.

There is a kiln there that I should have access to, so I just need some nichrome coils - I know people have done this before - so what gauge, length, coil size, and how many coils do I need to make... I should be able to get a few made up with just normal glass - I'll see how that goes before moving to the boron stuff...

I personally would like to keep it under 10 mm in width and don't know how long to make it.... But if the coil is in the bottom of a cylinder of glass, I can always make it shorter...

 

[roadkilldeluxe]

There is a kiln there that I should have access to, so I just need some nichrome coils - I know people have done this before - so what gauge, length, coil size, and how many coils do I need to make... I should be able to get a few made up with just normal glass - I'll see how that goes before moving to the boron stuff...

I'm not 100% sure on the gage. But the resistance you want (I think most attys are in the 2-3ohm range) will determine the length. My coils are about as big as they can be to still fit in the glass. The 510 is about 10mm, my bulbs are around 5mm in diameter.

What size wire and resistance should we aim for?

Bulb w/ coil

Length.. about 20mm

Width, 5mm

I heated the tip of a poorly cut bulb with a butane lighter. It smoothed out and the opening constricted, leaving a much smaller hole. I liked the result.

 

[jacko]

The bulb looks great. have you applied a voltage to the leads yet to see if it will glow?
The resistance should be in the 3-4 ohm range, I believe. It seems that what I have been able to find out should put the current at around one amp.... which is 3.7 ohms for a 3.7 volt unit. The wire that has been used before has been 36 gage. one to one and a half inches should get in the right resistance range.
When I can get some nichrome I'll try to help too.

 

[roadkilldeluxe]

The bulb looks great. have you applied a voltage to the leads yet to see if it will glow?
The resistance should be in the 3-4 ohm range, I believe. It seems that what I have been able to find out should put the current at around one amp.... which is 3.7 ohms for a 3.7 volt unit. The wire that has been used before has been 36 gage. one to one and a half inches should get in the right resistance range.
When I can get some nichrome I'll try to help too.

Excellent... this sounds good to me. Now what's the best way to solder the Nichrome to the copper? All I have is regular rosin-core solder.

Also, if this was used as a cartomizer, would the two leads have to be insulated, since they will be surrounded by liquid? Or does it not really matter if they are both bare?

Edit: I will try to edit my OP every once in a while as we gather more knowledge. I've updated/reorganized it and added two great links related to working with glass: 1 2. This should help anyone attempting anything similar...

 

[roadkilldeluxe]

Experiment #1: I did a quick stress test and it didn't turn out well for the bulb.

Volts: 5.00v from a computer power supply
Coil: 3.5" of 32ga NiCr (3.2ohms, theoretically)
=1.56 Amps
=7.8 W (theoretically)

Observations
-Running at 7.8W dry, in free air, then dripping onto the bulb directly caused it to crack all over. Carlos49 mentioned the possibility of this happening.
-The cracked bulb maintains its shape but will separate into pieces with minor force.
-My "PG/VG 80/20" mix vaporized violently upon contact with the glass directly above the coil
-When juice is dropped onto the very tip of the bulb, it hangs there, slowly vaporizing. This tells me that only the glass immediately next to the coil will get very hot.

Hopefully this establishes the worst-case scenario as I doubt anyone will be vaping with 32ga and a computer power supply directly onto a bulb in free air.

Before

After

 

[moktarino]

Excellent photos!

I'll continue to follow this thread with great interest, but I've got to be honest with you.. I'm not personally sure I understand what you're trying to accomplish.

Let's say that you are ultimately successful with getting some nichrome put inside of a glass bulb or coating. And that you are able to figure out how to get the time constant down so that it heats up quickly enough. Then what?

You still need to devise a delivery mechanism for the e-liquid.

Well, you know what they say about eating elephants - use an enormous blender and a big straw!

Seriously though, yes the feed mechanism needs to be designed as part of the overall form factor of the device. The atomizer, battery (if any), reservoir, and electronics must be integrated into a cohesive whole for a successful device, like pieces of a puzzle that complement each other.

The goal of the glass-encased heating element is to solve the oxidation and maintenance issues related to the "disposable" atomizers. I'm not interested in a disposable device. I can deal with replacing a wick, but I'd rather not replace the heating element.

In my head, at least, the form factor consists of a pipe. I've never enjoyed cigarettes or thin cigars (bidis, perhaps), and the extra space provided by that form factor will allow for significant "wiggle room" to accomodate less-than-precise engineering.

I think that to accommodate the "instant-on" feature, the glass barrier between the nichrome and the glycerin will need to be exceedingly thin.

I'm trying to acquire some of the pipettes I mentioned in an earlier post, I think I can stretch them out to make them thinner with the judicious use of a blowtorch.

 

[Applejackson]

Not to be a killjoy here, but has anyone considered the fact that PV's tend to get jostled and bumped around pretty regularly, and the glass could easily be broken without you knowing. Also, unless it's Pyrex, the heating/cooling is going to break the glass eventually. Last thing I need is an unexpected mouthful/throatful/lungful of broken glass. I just don't see any way this could be accomplished safely. Glass is just not a material I want in a PV mechanism. Definitely an interesting idea though.

 

[moktarino]

Experiment #1: I did a quick stress test and it didn't turn out well for the bulb.

Volts: 5.00v from a computer power supply
Coil: 3.5" of 32ga NiCr (3.2ohms, theoretically)
=1.56 Amps
=7.8 W (theoretically)

Observations
-Running at 7.8W dry, in free air, then dripping onto the bulb directly caused it to crack all over. Carlos49 mentioned the possibility of this happening.
-The cracked bulb maintains its shape but will separate into pieces with minor force.
-My "PG/VG 80/20" mix vaporized violently upon contact with the glass directly above the coil
-When juice is dropped onto the very tip of the bulb, it hangs there, slowly vaporizing. This tells me that only the glass immediately next to the coil will get very hot.

Hopefully this establishes the worst-case scenario as I doubt anyone will be vaping with 32ga and a computer power supply directly onto a bulb in free air.

Yep, that's the reason most laboratory glassware is borosilicate. If you melt some borosilicate glass and stretch it out into a long fiber, it will be quite flexible. If you stretch out flint glass it will be very fragile and break easily. It's that stretch that keeps pyrex from cracking during heating, especially after many cycles.

Good! you've proven that it will work in concept, now we need to refine further

I found a good supplier of nichrome wire on ebay and used the ohms/ft values given to make a small table of the lengths the various gauges would require to achieve 3ohms:

38 21.12mm 0.83in
37 24.79mm 0.98in
36 30.05mm 1.18in
34 44.82mm 1.76in
32 71.44mm 2.81in


I just had an interesting thought... perhaps the tube could be bent 180deg to form a loop with an axial coil running through it... The open ends could be secured with epoxy into a holder of some kind or crimped around the edges of the nichrome...

I wonder if you could use that with a compression-based socket, allowing for easy removal.

 

[roadkilldeluxe]

I think that to accommodate the "instant-on" feature, the glass barrier between the nichrome and the glycerin will need to be exceedingly thin.

I'm trying to acquire some of the pipettes I mentioned in an earlier post, I think I can stretch them out to make them thinner with the judicious use of a blowtorch.

I completely agree. I'm sure we could even find the perfect size glass rod online, then just cut it to size and seal both ends... I really wish I had the tools to play with glass.

I need more butane and hopefully I can make use of it somehow. It cleaned up the ends of that one bulb pretty easily, though. They were pretty ragged/sharp, which is why I wasn't scared to test it in a super hot flame in the first place.

Not to be a killjoy here, but has anyone considered the fact that PV's tend to get jostled and bumped around pretty regularly, and the glass could easily be broken without you knowing. Also, unless it's Pyrex, the heating/cooling is going to break the glass eventually. Last thing I need is an unexpected mouthful/throatful/lungful of broken glass. I just don't see any way this could be accomplished safely. Glass is just not a material I want in a PV mechanism. Definitely an interesting idea though.

The glass is pretty sturdy, plus it will most likely be in the center of a metal atty housing surrounded by padding (i.e., wick/filler/etc). Pyrex would be very nice in the long run if this is successful. In my opinion, glass is the way to go because it's so.. clean. It's like cooking on top of a gross metal grill vs in a glass pot on top of the stove.

It seems like the biggest dangers most people are concerned with are the vapors from Nichrome, the wick, and the solder joint. This design will place all three elements within a protective barrier.

I found a good supplier of nichrome wire on ebay and used the ohms/ft values given to make a small table of the lengths the various gauges would require to achieve 3ohms:

I ordered from Jacobs'. Real cheap, $2-$2.50 for 10' sections, and free shipping on 26-40ga wire orders.

Is 3ohms the ideal? With a 3.7V source, we get 1.23A and 4.55W. Does this sound about right?

I just had an interesting thought... perhaps the tube could be bent 180deg to form a loop with an axial coil running through it... The open ends could be secured with epoxy into a holder of some kind or crimped around the edges of the nichrome...

I wonder if you could use that with a compression-based socket, allowing for easy removal.

You mean something like this?

That would be cool...

Any ideas on how to connect Nichrome to the circuit? I figured copper would have to be soldered directly to the Nichrome within the bulb. I read that since Nichrome oxidizes, the best approach is to tin the tips of the Nichrome and then solder it to another metal. Otherwise, the connection will slowly get weaker. However, my alligator clips seem to be working fine so far, the oxidation only gets heavy right after the contact points.

 

[punkman]

Been thinking about this a little and if I where to try to make one this is what I would
do.

Go to the store and grab a fiberglass wick for a oil lamp. Separate out one of the bundles from the wick. Wrap the nichrome wire around it in a vertical position just as you have done here with the bulb. The fiberglass wick should hold up to the heat and work nicely to pull the fluid to the coil. Cartomizers are constructed this way and is about the simplest design I have seen so far to reproduce.