Building a Digital Vaporizer (Brain Dump)

[skippymcware]

Alright, this is going to be a massive brain dump that is for my benefit as well as yours. If this "intro" is well received, I will continue with more posts that have more technical detail on the design decisions I am struggling with. Before I start, let me get a few things out of the way.

First, I just found this forum yesterday and have spent a great deal of time reading through it and absorbing what I can. Thanks to everyone for their informative and thoughtful posts. Second, the purpose of this post is to share my plans for building a "digital" (that is, controlled by an autotune PID temperature controller with a digital display for set point and current temperature) vaporizer. I am posting here because it seems like there is a good amount of accumulated knowledge amongst this forums users who will surely have some good feedback. Third, I want to make it clear that I am definitely not going to be building these for profit and, if I do make more than one, it will be for friends. That being said, anyone that wants to make their own is welcome to ask me questions, but I won't be much help until I finish the first one. Alright, on to my conclusions and problems thus far.



First Step: Optimal Vapor Temp

I started this whole process by looking into what the best temperature for a vaporizer to operate at. I found this paper and link:

http://www.scribd.com/doc/294969/Medical-Marijuana-Vaporizer-Study?autodown=pdf
http://www.canorml.org/healthfacts/vaporizerstudy1.html
*kudos to this forum for the second link...

Note that this study refers to the temperature of the air measured at the bud. If these seems obvious to you, you would be amazed at where companies put their thermocouples to measure the temperature. Anyway, this study says 365, and it takes them forever to do so. (No, I didn't read the whole thing)



Second Step: Survey Market

Volcano:
The first vaporizer that caught my eye was, of course, the volcano. This is not surprising, since the internets is spammed with people saying it is the "mercedes" of vaporizers. First impression of this device is that it is very simple and effective. Those two often go together, it seems. Here is a picture of the inside of the more basic unit:

http://www.vaporizer-volcano.com/wp-content/uploads/2008/10/volcano-vaporizer-hands-on-8.jpg

From what I have read, the volcano uses a constant stream of air that the digital version regulates the temperature of. The more work I have done on this project, the more I am leaning toward that system. I will get into that later. Again, from what I have read, it has an aluminum heating element which looks, from the picture, to be surrounded by some sort of ceramic or fiber/ceramic heat shield and the fan pushes the air through the heating element. The fan/pump is that large black thing in the back.

Super Vapezilla
Up until I saw this vaporizer, I wasn't convinced I could build a vaporizer. That's not to say that the Super Vapezilla isn't good. In fact, what I like about this unit is that it uses very standard components that are relatively easy to find. How do I know this? I found this thread:

http://www.wrug.net/forum/showthread.php?t=152

A special thanks to the moderator/owner of that forum (purceville, I think) and DigitalChaos (the poster who took all those pictures).

Looking at these pictures, we see a CAL3200 (in the U.S.) PID controller, a few fans, an AC/DC converter, a glass receiver for the whip, and what I think is a alumina ceramic heater. With these pictures in hand, I was about to start ordering things when I started to read some of the posts in that forum and others. This thread particularly concerned me:

http://www.marijuana.com/vaporizers/99219-super-vapezilla-other-vaporizer-reviews.html

In essence, the heating element that WickedRoots displays on their website (the one with lots of little holes for the air to pass through) isn't in the unit up for sale. In fact, in a survey done by DigitalChaos of the previously mentioned forum, not one person reported having that style heating element. Furthermore, the pictures show the thermocouple (that pair of twisted wires in an S shape) is placed waaaaay at the back of the heating element. I could be wrong, but that seems like a terrible place to measure the temperature of the air passing over your bud. I think it is a safe assumption that you have little idea what temp the air is on the other end of the heating element. Not to mention, users reported that the units take forever to heat up. Oh, and there is no way I am paying $500 for a vaporizer. So, back to the drawing board.

Vriptech
The main thing I noticed with this, and have confirmed after spending some time on the website, is that Steinel heat guns are really nice and have badass ceramic heating elements that cost $70 as a part. The main reason I like this is that the people at Vriptech have spent a bunch of time making sure that it is healthy to take hits of this thing. Component diagrams of the various guns can be found here:

http://www.steinel.net/resources/owners-parts.cfm

My main problem is in the implementation of this. It looks like the heating element is AC, and this makes life harder than it would be with a DC alumina ceramic heating element found on the Extreme Vaporizer or Super Vapezilla. The good news would be that it would heat up in 20 seconds and would have awesome control characteristics. That is, it is so overpowered that it could change the temperature of the air going through it really quickly. Another benefit is that the fan fits right inside it. Although heat guns are really noisy...

Extreme Vaporizer:
Many users have this vaporizer, and, from what I can tell, it is a really nice unit. My guess is that these guys aren't making a lot of profit off of each one of these. Although I don't have pictures of the unit entirely disassembled, it looks like the controller on this is a custom unit. I am particularly convinced of this because of the built in fan control and the LCD display. I could be wrong, though. Maybe there is an awesome controller like that available on the market that I haven't come across yet. I certainly haven't looked everywhere. Another nice feature is the heating element. It looks like a porous ceramic fiber. I can't really tell, as I only found one picture on this forum with the cover off. I can't find a link to that picture, but here is a decent shot of the top:


http://images.google.com/imgres?img...org.mozilla:en-US:official&sa=N&start=21&um=1

*damn... long link, sorry.

Anyway, I like the top load feature of this vape. It is also really nice to have the option of bag or whip hits. As of now, this is the leader of the pack in terms of what I will model mine off of.

Silver Surfer:
This seems like a nice unit. It has a nice heating element that is all ceramic. They talk about it at length here:

http://www.silversurfervap.com/glassceramicheatingelement.htm

Other than the heating element, there isn't much I am looking to emulate here. Although I respect their Keep It Simple Stupid approach, I am looking for something that will measure the temperature of the air flowing over the herb and be able to regulate it. I am not interested in units that give me a knob to blindly screw with until I feel like I am getting a good hit. I can use a lightbulb and a lighter if that is my plan. Plus, where is the fun in building something like that.

Others:
There are a few others that I have seen. Most of them have had startlingly bad reviews or make no attempt at measuring the temperature and correcting it. Many of them have digital displays that show temperature, but it actually just a scaled voltage or resistance reading showing your knob setting. If done properly, you can calibrate this to the actual temperature of the air, but is a dubious assumption at best. I will talk more about this later. Finally, there are a bunch of portable/gimmicky vaporizers (Vapir, for one) that I am not looking to copy. I want a bag/whip style hands free vape that is relatively stealth and very accurate.


Important: If there are any I missed, let me know. I am looking to gather as much information as possible here.


Final Comment: Everything I put in these posts is just my opinion drawn from what I have read and my own personal experience. I could very well be wrong. It happens all the time. I don't want to start any flame wars with people who stand by their favorite vape that I didn't like/mention. This should be obvious, but you never know.

Ok, that is is for the intro. I will follow with posts that are as technical as possible on each individual component of the vaporizer and the work I have done so far. It is amazing how many decisions go into the smallest things. The proper tubing is a good example. I figured that would be easy. WRONG! At the moment, however, I am tired of writing and want to get an interest level reading from this forum. If no one cares/reads this, then I won't continue. Also, let me know about any other forums that would be useful/interested in this information. Hope this was helpful or enjoyable for someone out there on the interwebs. Thanks for reading, if you made it this far.


I just realized that I might not have posted this in the best section of the forum... Let me know if this post should be in vaporizers or general. Thanks.


-skippy

mod note: posts merged

 

[Purple-Days]

Can'tyou use the steinel element as a DC heat source? Sure the fans in those guns run AC and therefor they run AC to the Heat source, but would the heater 'have to be AC powered? (don't know the voltage required, but heating elements seem to work as well AC or DC at the proper voltage, fans are the problem, not interchangeable) If you can run the Steinel on DC would that make the CAL3200 an option as a controller?

Next thing to consider is air-path safety. I notice you already have some concerns. RoHS compliance of all electronic parts is the first step. Elimination of non-food grade plastics in the air-path might be another. Plenty of makers that don't seem to care about either.

While 365F sounds good, in practical application, it is not so critical that you be exactly right, rather that you be able to repeat a setting (and maybe adjust if you are uncertain or have variable needs). If your readout says x and you like x and you can repeat x it doesn't really mater if the numbers are perfect. Just a thought, since this isn't for mass market.

Best of luck,
Tom

 

[skippymcware]

Post Number 2

Although I left out a lot of details in the first post, I just wanted to get the basics down. This post is going to be some more setup and background, and then I will take on specific components. Remember that this is a work in progress, so my conclusions are far from written in stone.

The next order of business is to layout the design process. My best guess is that it should go like this:

Design Steps:
1. Survey market.
2. Do as much reverse engineering and information gathering as possible on the good products.
3. Put together a list of design goals. (bag/whip, digital display, temperature controlled, glass on glass, blah blah blah)
4. Identify best case scenario for each design decision.
5. Modify design given that money, time, and resources are not infinite.
6. Start choosing components.
7. Modify design to fit said components.
8. Build and test.
9. Iterate step 7 and 8 until satisfied.

I will try and stick to this order as I continue to post over the next few months, but design is a tough process and all the steps get muddled up. For the next few weeks I will be sticking to steps 4 and 5 while I narrow down the best (while still practical) components to use.


Step 1 has already been accomplished. Although, I am open to more suggestions.

Everyone here will hopefully help me with Step 2. I have done about as much as I can do without reading every post in every vaporizer forum out there.


Here is Step 3 with a short intro for each on some of the decisions involved:

Design Goals:
-Stay healthy and chemical free. Just being a vaporizer gets this project off on the right foot. However, this also means avoiding all the materials such as tubing, heating elements, plastic cases, painted enclosures, and various other things that could release harmful toxins into the vapor. It is amazing how much stuff I have seen in popular vaporizers that, to the best of my knowledge, isn't rated for the temperatures being seen. ("Medical Grade Tygon tubing is one example. As far as I can tell, it is only rated at 200 F. Correct me if I am wrong. Edit: I was corrected because I was wrong. I made the mistake of only looking on mcmaster-carr for the tygon. They have 3 billion kinds, but none of them are high temp. I figured if anyone would have it they would. Anyway, sloppy work. Sorry.) Most of my time has been spent in this area so far.

-Built like a tank. If the meaning of this isn't obvious, it means that I won't spend more time fixing this thing than enjoying it. A lot of this has to do with quality construction and selecting the right components. The rest just falls together with a little thought.

-PID (Proportional Integral Derivative) Temperature Controller with Autotune and a digital display. This controller will watch the temperature input I give it and adjust the power to the heating element so that the air crossing the thermocouple (temperature sensor) will remain at the set point temperature. These controllers are present in the Volcano Digi, Extreme Vaporizer, Super Vapezilla, and several others. Some of these use controllers that are widely available, such as the Super Vapezilla and the CAL 3200 (about $170). Others look like they have custom units or units from less well known manufacturers. I am looking at several units from Omega. They have a very decent offering, the CN7533, for $89. The supplier Instrumart also has a bunch of units from other companies. This component, along with proper placement of the temperature sensor, should pretty much guarantee a good vape hit.

-Isolate electronics from the heating element/chamber. Cleaner and healthier this way.

-Convenient whip design. I noticed a lot of people struggle with horizontal whip configurations. I would like to avoid this, but it changes the form factor of the whole unit around. I will be interested to hear what people have to say about this when I get to it. This will be discussed after I select a heating element and controller.

-Insulated. The exterior of this thing needs to be cool enough to touch. I don't want any third degree burns while I am vaping. It is hard to remember not to touch something when you are blitzed.

-Stealth. When completed, this device needs to look clean and professional. I can't have something that looks like a mad scientist experiment. This should be relatively easy if I can fit it into a hard drive case (although this would have to be a horizontal whip design)

-Whip/Bag. This decision is completely wrapped up in the overall design of the device. I will address this in the next post where I discuss the various options I have come across for the heating element.

-Fan control. Whether or not the unit will have a fan that pushes air through the heater, it will need to have a cooling fan for the heating element. Like the extreme vaporizer, this should have either a timer or shutoff when the heating element reaches an acceptable temperature. People often complain that the Super Vapezilla takes forever to shutdown because you have to push the temp control buttons over and over to lower the temp and then leave the unit on for a while to let the fans run. Some solved this by adding an extra switch so the fans ran on their own circuit.

-Active Carbon Filter. Active carbon is awesome and I have heard only good things. I am strongly considering making this an integral component.

-Glass on glass. Everyone loves it. I will need to get my components from a company that is going to be around a while. I would hate to break something down the road and have to change the design around because I couldn't get a replacement part. I hate to say it, but Roor is calling...

-Speaking of Roor. This thing needs to be affordable. If I didn't care what I spent, I could build this next week. I do care, though. I am trying to improve over what I have seen. Furthermore, a lot of this is an exercise that is about the journey. I wouldn't be posting all this if it wasn't.

-Standard components. I mentioned this earlier. I want all the parts to be easily found and widely available. This required sacrifices on the design end. If I had things custom made life would be way easier.

-Attractive final product. Obvious, but not easy. Once I get the majority of the design work done on this thing it is going to be a bunch of work to make it look nice.

-Quiet. I don't want this thing to sound like a jet engine when the fan is on. This will probably come down to fan choice. You can buy them with mag-lev bearings that make the fan extremely quiet. Sunon makes some of these. You can see them in the pictures of the internals of the Super Vapezilla.

-Easy to clean and maintain. Loaded statement. This is dependent on solid design of the device.

That's all I have thus far. I will add more of I come up with it.

Thanks for reading. Next up, I will go over heating elements and all that I have found. This is where I will want to start getting lots of input. I can't find a cheap good heating element for the life of me.

-skippy

 

[rukus13]

Sounds pretty awesome. I will be following this thread. Always wanted to build my own just for the experience. You mentioned active carbon. What is the reasoning for this? Do you mean at the air intake or what? Seems pretty unecessary if the air in the room is good enough for breathing its good enough for vaping. If you are planning to put it in the air path that would be a bad idea anyhow as I wouldn't want to be inhaling carbon dust. Maybe I'm misunderstanding but I'm curious.

 

[lwien]

Important: If there are any I missed, let me know. I am looking to gather as much information as possible here.

Regarding unique heater controls, check out the Aromed. Apparently, they have a microprocessor that constantly monitors the temp within the herb rather than at the heat source, and adjusts to preset temps.

http://www.aromed.com/en/aromed.html

 

[skippymcware]

Tom,

Several good points. I will need to look into the steinel motor a little bit more. I would love to use it, but it will be tough to mount and heat gun fans are noisy as hell. It would be great, though, if I can make this whole thing with only AC power. I am a mechanical engineer, so my electrical know-how is pretty weak. I have an electrical engineering buddy that is going to help me out with this when he has time. I just dumped a boatload of info. on him the other day so I need to wait until he catches up.

You speak the truth when you say the real goal is repeatability. As I mentioned in the second post, though, I am doing this as a fun project to see how well I can make this thing. There may be something wrong with me, but I love a good engineering project. If it isn't obvious from the length of these posts, I have some time on my hands as well.

I am not familiar with RoHS standards. I will look into them. It's strange, I got a UK site when I searched it on google. Maybe there is a US equivalent? Assuming that some of the electronics I put in there aren't, it may be sufficient to seal them in another compartment with some high temp RTV silicone.

Thanks for the feedback. Sorry for some of the boiler plate, but I am trying to use this as a log of the project as well as a place to gather input. I will get into the nitty gritty details in the next post.

-skippy

 

[skippymcware]

rukus13,

I am referring to an active carbon filter placed downstream of the bud as seen here:

http://forum.grasscity.com/recreati...ong-carbon-filter-surprisingly-effective.html

Is it necessary? I honestly don't know, but people say it doesn't detract from the potency of the hit. Mostly they comment on a decrease in flavor. But, if that means the vapor will be very near 100% carcinogen free, then I might be willing to deal. Again, I just learned about this, so I am just throwing ideas around.

Hope that helps,
-skippy

 

[skippymcware]

Iwien,

Very interesting. Question is, can I buy it in component form. I will go over this site in the next few days.

Working from the general concept, I suppose you could use an infrared temperature sensor and take the temp of the herb. I am concerned that this would be tricked by hot spots in the herb or reflections off the glass. It would be tough to implement since you can't measure air temperature with it. In general, this seems like it would just be extra technology for the sake of extra technology.

I think Tom (Purple-Days) brings up a good point that the simplest devices work well because they are repeatable. I am, knowingly, ignoring some of this wisdom because I want an engineering challenge and to make something that can compete, in a sense, with the "high end" vapes. Hopefully, it will do this for less money. I am going to do everything I can to make that a reality.

Thanks for the heads up,
-skippy

 

[vtac]

Well I'm impressed.

Gotta make this quick but I'll try to help a bit here, forgive the disorganization.

In regards to temperatures, 190C seems to work very well for vapes that maintain a set temperature such as the PD and iolite. You're right, highly accurate digital monitoring is difficult. The sensor would need to positioned directly on top of the herb or in the middle of it. And then you only really get the temp when you're drawing the heated air over the probe.

The ability to maintain a consistent temp when being hit hard back to back is important. As far as fuzzy logic goes, the Vaporfection comes to mind- Stonemonkey55 has said his unit does an great job at compensating- after sending it in twice for service. Not sure if you'll be able to get him to rip his apart though. Other vapes have proven you don't need a controller regulating the heater. A large heat reserve in a heat exchanger can be very effective. Here's one.

Your design goals look good, though satisfying all of them might be challenging. "Built like a tank" is great for clumsy stoners but from what we've seen, vapes with digital controllers and relatively complex innards are more likely to fail. Heat and electronics... Glass on glass is great but again, clumsy stoners. Keeping it affordable and using standard parts might be difficult with highly accurate digital controls. If you can pull it off, hell yeah go for it, but it sounds like you might be trying to cover too many bases.

I know there are a few pictures of a disassembled Extremes floating around on this forum. Here's one.

Carbon filtration might be going a bit overboard with vapor. From my understanding/recollection, carcinogens don't start appearing in any significant amount unless you're vaping at near combustion temps. Flavor reduction is a bad trait in a vaporizer.

Hope this helps for now. It's really awesome to see someone taking such a calculated approach to this, thanks for sharing. If you want feedback from some experienced vaporists you're in the right place. If and when you need some experienced beta testers just let me know.

("Medical Grade Tygon tubing is one example. As far as I can tell, it is only rated at 200 F. Correct me if I am wrong.)

There are a few grades/types of tubing under the Tygon brand. This one is rated at 400C

RoHS

List of All Vaporizers

Anway, nice thread, bookmarked.

P.S. Paging nicelytoasted and Spiderman to this thread.

 

[vtac]

OK i just skimmed through 40 pages of the Extreme thread for you. New post in case you already read the above.

http://www.fuckcombustion.com/viewtopic.php?pid=1872#p1872 (post #254)

 

[skippymcware]

vtac,

Thanks for the comment. You have already given me lots to think about. I will look into the vaporfection over the next few days. (I am going out of town until Sunday for business, so my replies will be much slower.)

As for digital control, it is definitely tough. It will take quite a bit of work to get right. It is definitely a strategy to use a large heat mass/ballast instead of precise control. I am going to shy away from this method because it will add a lot of weight to the unit. My conviction, and I think several units on the market have proved it, is that it is completely possible to regulate the air temp over quickly changing air flows. To do this, you will definitely need the right components and layout. From a quick glance at the website for the Supreme Vaporizer, I would agree with them that the heating element is the most important part. Because of this, I will address the heating element in my next post and it will dictate the rest of the design. Other than that one point, it looks like the guy who designed that device was somewhere else when they made that website. Interesting design, though.

You may be right about too many lofty goals. But the point of the previous posts was to engage in blue sky thinking. I just wanted to think of anything and everything that might make the final product better. You have got me thinking about the glass on glass. I will start looking into some other quick disconnect couplings. Maybe there is a better option out there... just need to make sure it doesn't give off nasty fumes at higher temps.

You commented on my statement about the unit's durability. I am not looking to design a device that can get knocked off a table and keep on kicking. I just want it to be solid and rugged enough to withstand years of regular use with minor maintenance and cleaning.

Again, as I eluded to in one of my previous posts, it may be the case that active carbon is unnecessary, but I wanted to throw it out there. When it comes time to make this thing a reality, this will probably be one of the first things on the chopping block so I can fit this whole contraption into a nice enclosure

Thanks for the links to RoHS and Tygon. I corrected my previous post about tygon. I don't want to start any nasty rumors. There are plenty of those running around.

Thanks for the input. I will check in while I am out of town, but not this frequently. I will try and put together a brain dump on heating elements. I really want to get that stuff up here because it is the only real road block to finishing this project.

-skippy

 

[skippymcware]

vtac,

You are the man. Seriously. I tried to go through that whole thread but lost steam after about 25 pages. I shouldn't have started from the back!

Damn... custom components. Huston, we have a problem. They are smarter than me. Lucky for me, I brought my electrical engineering friend/backup. Anyway, the whole point is to make the volks-vaporizer (haha, get it?!... bad I know) with parts anyone can buy. Whether or not this is going to be something anyone can afford is still up for grabs. I am gonna try for it.

Thanks again. I will put those to good use. Rest assured, your 40 page thread skimming bonanza is not in vain.
-skippy

 

[rukus13]

rukus13,

I am referring to an active carbon filter placed downstream of the bud as seen here:

http://forum.grasscity.com/recreati...ong-carbon-filter-surprisingly-effective.html

Is it necessary? I honestly don't know, but people say it doesn't detract from the potency of the hit. Mostly they comment on a decrease in flavor. But, if that means the vapor will be very near 100% carcinogen free, then I might be willing to deal. Again, I just learned about this, so I am just throwing ideas around.

Hope that helps,
-skippy

Ah okay I get it now. I'd skip this unless you plan to integrate some sort of water filtration. The problem is that any carbon I've ever worked with releases tons of carbon dust. In the post you linked the water would filter this out. I wouldnt want to inhale that stuff straight up though it just cant be good for your lungs. Plus like someone else pointed out taste is a plus with vapor unlike combustion. I cant wait until you actually start to build this thing.

 

[Purple-Days]

What I hadin mind was using the steinel heating element itself, not the gun or the gun's fan. Hybrid, AC and DC. AC heating element and DC cotrollers and fans.

On fans. They scream like a jet engine. I owned a S-vzilla. Loud as a cat cought in a trap. Allthat non-sense about nag lev bearings.... It's those blades whizzing through the air that are screaming, not the bearings. Sure the better bearings make it wuieter, but the difference is heavy metal vs hard rock. Not much. MAny don't thjink 'forced' air is required.

Carbon is a bad idea. Drop it now.

Plastics are temp rated with liquids and pressure. Neither apply to a whip. Tygon ( a decent grade) is fine downstream. Obviously not for dirrect contact with the heat source.

RoHS is an EU standard, but those standards are applied here (USA) and my electronics sources all list RoHS compliance (or not) for the various electronic components. Even though it wasn't started here, RoHS compliance is avaiable here. Always a little more expensive.

High temp caulk? Brominated? Watch what you use. Pure GE silicone is rated for food safe work. Not so sure any high temp caulks are, even if they contain or are labeled 'silicone'.

Most commercial cases are powder coated, or baked enamel. If you could find raw aluminum case, no paint, you could avoid some of your health concerns , but will trade off in looks.

If you consider infra-red monitoring, why not monitor the aIr-path directly after the herb, glass on glass fittings would allow this.

As mentioned I owned a S-vzilla, glass on glass. When the frosted glass on frosted glass get stuck together it's a bitch. I'm not the first to notice. Even S-Vzilla says, 'don't insert all the way' or something like that. OK, you talk about what you can handle while blitzed, try holding the two glass pieces 1/16" from complete insertion. What a joke.

And glass is glass. Fragile. Bought three 'bowls' for the SV, ended with one left before the controller gave out.

If it can't take a drop from table to floor, it's not built like a tank. Period. If it's made to sit and never be dropped it doesn't need to be built 'like a tank'. Decideon one or the other.

Oh back to the controller. The zilla design sucked. As you mentioned, mashing buttons every time you need to shut down or start up ... well those buttons don't last forever, so being able to set the temperature once and use a switch to control on/off and fans (if needed) is a fix. But uhoh, you just built a set temp vape. Sure you can make little adjustments, but once you find the 'sweet spot' guess what, that's where it stays, no need for adjustment unlesss you are using different herbs. Not putting down adjustable temps or digital control, just giving my experience with a digital controlled vape. It got set to the same temp most every day.

On whip position. Horizontal is fine. Most problems there come from a lightweight case (wood box vapes) and the stiff whip wanting to move the box around. Rubber feet and a little weight and that is solved. Better plan on rubber feet if you plan on a fan anyway.

Cool down. There is a hurdle. It would have been nice to mash a button and start a cool down cycle that ended with the unit turned off.Again, back to the SV, you could start the cool down nbut the unit did not shut off. Gotta run outta the house quick? Not an option. Bad idea, IMO. Wait 20 minutes for cool down so you can throw an off switch, hell I'm ready for another hit by then.

Gotta run.

 

[stickstones]

I would suggest looking at two vaporizers.

I like two things about the design of the Aromed...it uses a halogen light bulb, which has to be much cheaper than anything ceramic. I also like that it heats from the top...marcuss mentioned that this could preserve the life of your bowl as heat is only passing through it when drawing. I would think the bulb heating thing is something you will want to explore in the name of cost and replaceability.

Another is the VM3. I thought somewhere you mentioned portability. Maybe you mean easy to break down and set up elsewhere instead of using on the go...please clarify. I just finished using the VM3 for a review and I think it is a very ambitious unit. It is a portable that fits in one hand and can be operated with one hand. It is easy to load, comes with extra loading discs, uses internal rechargeable batteries and has a digital temperature control. In other words it has all the features you could ask for. Unfortunately, I didn't think much of the vapor quality...taste or effectiveness. It's the perfect example of what you are trying to avoid...an expensive, feature-rich device that doesn't really satisfy.

I started out with my first vaporizer being an Extreme. It has all the features and bells and whistles you could want and works very well. I was glad I got a digital vaporizer and felt like I had all my bases covered. However, after starting at the pinnacle of versatility, I now find myself reaching more often for the simpler ones like the Purple Days (PD) and the Iolite (II). When all is said and done, it comes down to the vapor and the experience. It's a real joy to use something that all you do is turn on and suck...and every time it gives thick potent clouds. I would think this would be your ultimate goal. As you get further into this project, or earlier if you wish, I suggest thinking more about simplicity and cost and less about features and digital control. The PD, II and LB (LaunchBox) are perfect examples of these things just not being necessary.

Please keep this project up and us updated...I am very intrigued!

 

[stonemonkey55]

skippymcware - Hey really cool thread. Just wanted to add my 2 cents here.

Fans - yes the Super Vapezilla fans are noisy but the ones that they use with the Vaporfection and Evolutions unit are whisper quiet. The Vaporfection fans are quiet but whatever the Evolutions unit used, those were even quieter.

Digital controller versus thermal mass - a buddy of mine came over this weekend and brought a device that you could point at something and get there heat. It wasn't an infrared device but if you looked at the LCD screen it would show an outline of the person you were looking at and the hot areas would be red and cool areas would be blue. He had one of those sensors, sorry that I can't remember what it was called.

First we used it on the Vaporfection, we found that without anyone taking inhales, the hot air from the outtake fluctuated 15-25 degrees. We pointed the the device at the top of the Vriptech while I took inhalations and only got 10 degree fluctuation. The VHW uses a simple rheostat (I beleive) to control its heat and it seemed to do a better job due to the thermal mass of the glass heat cover. For me, this is a big reason why I prefer this unit over vapes like the SSV where your breathing pattern controls the temperature and affects the type of vapor you get. Hope this helps.

 

[skippymcware]

Tom,

I meant to convey that I was trying to use the heating element and investigate into using the fan. I think we both agree that the fan will likely be too noisy.

It's good to know those mag-lev bearing sunoco fans are crap. I will avoid them. I am confident I can find a fan that is quiet, however. It would be absolutely fantastic if I could avoid forced air all together. Heat element choice will dictate this. Many heat elements require a minimum flow. Whether or not this applies to the implementation of a controller, I still need to investigate. Again, I need to finish my piece on heat elements before I discuss this further, but I included a short piece on it below.

It seems everyone agrees that active carbon filtration is a bad idea, and I am starting to agree. Rest assured, if it sucks, it won't end up on the final product.

Good advice on the caulk. I will burn that bridge when I get to it. Lots to do before then.

I may end up fabbing my own case... I would like to avoid that, though. I don't have any of the sheet metal tools here and it breaks the standard parts goal.

I am skeptical of infra-red temp measurement. Another bridge to burn for later...

I am starting to lean away from glass on glass. I need to find a good substitute. Another bridge...

Message received on the necessity of temp. controller. If at all possible, I will buy the components and try the setup in several configuration. I will setup a test bench and try it in the following configs:

1. Without controller and forced air
2. Without controller
3. Whole shebang

The practicality of this will depend on the heating element choice.

It would be great if I didn't need forced air or temperature regulation, but my concern is the following. I am going to get into the heating element design a little bit, but am at an airport, so I have limited time.

The formula for the necessary power needed to heat an airflow passing through a heating unit from temp a to temp b is such:

Watts = SCFM x DeltaT in F
3

Here, DeltaT = [TempB-TempA]

In our case, TempA would be room temperature (about 65). TempB would be the air passing over the bud. Our target, thus far, has been 365, but I will use 375 F to give a safety cushion. Make sure we get that thc nice and vaporized.

SCFM is the standard volumetric flow rate of the air through the heating element. I am looking around for some medical literature on volumetric flow rate on peoples breathing. In the absence of this, I have done some back of the envelop calculations:

Using this link:

http://en.wikipedia.org/wiki/Lung_volumes

Designing for the biggest hit possible, I used the "Vital Capacity" lung volume from the link above. Given this, the volume of air inhaled is about 4.5 Liters (.159 cubic feet).

On top of this, I figure a hit takes about 10 seconds.

I am ignoring the "Standard" part of this metric because it is compensating for atmospheric conditions and various other things. This is a back of the envelope calculation, not a thesis.

Given this:
Volumetric flow rate of a hit is .959 SCFM (cubic feet per minute)
*I will replace this with some of my own measurements taken experimentally, or someone else's that were published somewhere.

Ok. With all of this information, you can calculate the number of watts that your heating element needs to dissipate into the air over its heated length. It should come to around 100 watts. This is a surprisingly low answer.

Why do I bring all of this up? If you don't have a constant air flow rate, like the volcano, your SCFM will be zero most of the time, and then 1 or more during a hit. Not to mention, as others have suggested here, everyone is a little different and may have larger or smaller breathing patterns when they are toking. If you rearrange that equation and plug in a constant for the power (watts), you can then solve for deltaT (which must now change). This tells me that your air exit temps will not be constant. How much will they vary? I don't know yet.

So, where does this lead me? It only tells me that I need to try a bunch of stuff and take some temperature measurements. If I can keep the air temp going over the bud at a relatively constant 365 F (+/- 15 degrees worst case!), it may not be necessary to add all the controllers and forced air blah blah blah. I aim to figure that out, though, not just accept that the simplest system is the best. I will keep going on this when I get a chance to write the next post.

As for the durability. You are a hard taskmaster. I came here for this exact reason. It sounds like you have been down this road before. Although it may be painful for you to watch, let me walk it as well. With any luck, I will come to the same sound conclusions that you have. I think we can both agree what a well built and rugged device is. I am shooting for that. Remember, the design goals list above is a set of goals. They are platonic ideals that may or may not be reached. Hopefully, I can hit most of them.

Thanks for your thoughts and keep them coming,
-skippy

 

[skippymcware]

Slickstones,

Given that I am really struggling to find a heating element, I will definitely look into bulb heating. Off the top of my head, it poses mounting and form factor challenges. Specifically, it would be hard to mount the bulb over the herb and still have everything easily accessible while also being compact and neatly packaged.
*Edited this... I was writing way to fast. What I said made no sense.

I am not really interested in portability. The unit does need to fit nicely in some sort of enclosure, but that is about it. I picture some sort of rectangular/square case with cutouts for the elements.

I agree that simplicity is always a fantastic goal. I submit that just because something has a great deal of technology in it does not mean it has to be complicated to use. This often requires a very excellent understanding of the technology being used and a great deal more effort that would otherwise be required. I think Apple is a good example of a company that has actually increased the amount of technical knowhow in their devices in order to make their devices "simpler." In any case, there will be a time for paring this whole project down. That time has not come yet.

Thanks. Its good to have your input,
-skippy

 

[skippymcware]

Stonemonkey,

That sounds like an infrared camera. I have seen one used in a lab once before. They are sweet. I wish I had one, but they are far from cheap.

I will look into the devices you mentioned, but I have run out of time at the moment. I will get back to your post later.

Thanks,
-skippy

 

[Purple-Days]

Skippy the mods like it if you use one post rather than consecutive posts. Just a heads up. I know they are ;long answers and probably deserve each space.

"On top of this, I figure a hit takes about 1 second" ??? Typo???

And I tyhink you should be trying for 190C,a bit higher than your present target of 265. While 365 is the boiling point of CBD it is barely that. So it's not a rolling boil if you get my drift.

Yesusing the heating element from steinel (the part you referenced) and another fan system makes better sense. On Fans, who knows what those fans in the back of the zilla were, that name sounds familiar though, I would have to dig it up, but as you already pointed out about their heating element and by reading their words, all of it is subject to change without notice...

Hmmm. you want non-science project look and worry free about hot parts, and a custom case, consider wood, many box vapes use a wood case. No reason you can't use 'nice' wood if you go theat route..

 

[vtac]

Skippy the mods like it if you use one post rather than consecutive posts. Just a heads up. I know they are ;long answers and probably deserve each space.

Back to back posts with minimal content/justification are the problem. Not the case in this thread.

 

[stickstones]

skippy...that 1 second draw stood out to me as well. Every vape I draw on gets between a five and twenty second draw depending on which vape it is.

Do you have a lot of history with vaporizing?

 

[Purple-Days]

And I'm still waiting to see a vape based on a 12V DC ceramic element from a Subaru? obviously meant for inhalation. If interested I'll dig up some info Skippy, but I thought it was a potential off the shelf heater with a legit background for this use.

 

[tuttle]

The formula for the necessary power needed to heat an airflow passing through a heating unit from temp a to temp b is such:

Watts = SCFM x DeltaT in F
3

Here, DeltaT = [TempB-TempA]

In our case, TempA would be room temperature (about 65). TempB would be the air passing over the bud. Our target, thus far, is 365 F.

SCFM is the standard volumetric flow rate of the air through the heating element. I am looking around for some medical literature on volumetric flow rate on peoples breathing. In the absence of this, I have done some back of the envelop calculations

If you are this intent to hold a constant temp on outlet air for a whip style use, I think you are going to need a flow meter on inlet to know when to increase current during a heavy draw. That is probably a lot more than you want to get into, but if the goal is not to require the user learn the vape and draw at the correct speed (like you need to do on the SSV) and maintain whatever temperature was set by the user regardless of draw speed, then you need the vape to know what the user is doing to compensate.

Very interesting project

 

[skippymcware]

Everyone,

Sorry. Crappy mistake on the quick calculation. I was doing it in the airport terminal. I went back and fixed everything up. New power requirement is 100 watts worst case scenario. This seems like a terrible answer but I pushed everything to the max to get a larger power requirement already. I used max lung capacity and 375 instead of 365 degrees. I will have to find a tricky way to measure the volume of some deep breaths. Can't be too hard. I know a couple of med students. Maybe they have some tricks.

As a side note, I think this sloppy mistake signals that I should stop turbo posting information and sit down and write that next post I keep talking about.


Tuttle,

Good to have you aboard. I really doubt I will need a flow meter. I think what I will need is a heater that has a very quick temperature response (due to a very small heat sink capacity) to applied voltage changes so that the exit temp can be corrected extremely quickly. I could be wrong, but that is what I am gonna find out. A good example of something like this, which I will not be able to use (as far as I can tell) is this:

http://www.sdiohio.com/Documents/Series Op Man.pdf


Tom,

Definitely look into that subaru ceramic heater. I have a 2000 Subaru actually. I will check into that when I get home.

I am gonna start writing this heating element piece. It seems like the next logical step.

-skippy