darkstar72
Well-Known Member
If interested in the hand railing idea, consider the 1 and 3/4 inch diameter wood dowel from Bell Forest, linked here.
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'The Misty Log' - DIY wooden Log Vaporizer
- Thread starter blokenoname
- Start date
Shouldn't be afraid of a little torch action when solderingAnd please don't ask me, how I managed to solder the connector pole to the nichrome... had s/thing to do with me getting pissed with the soldering iron & taking the jet flame to it
I use it to get the solder off of the barrel jacks for reuse, or preheat big stuff. All about getting the heat where it needs to be.@Flotsam Good luck with the build. This project has really showed me how simple a vaporizer can be. And thanks for the link to the dowels @darkstar72.
I've been working on a new halogen design, incorporating the larger 2mm tubes for heater sockets. I think that forming these into sockets can actually work quite well. Been using a pair of round nose pliers, like this: https://www.michaels.com/product/bead-landing-round-nose-pliers-10035773 to form the contacts. I use the small flat part to crush the tube flat while the bulb pin is inside it, then take out the bulb and gently compress using the round part until the pin fits tight. If you go too far you can squeeze it back. Once the tubes are mounted in a base its pretty easy to take the bulb in or out.
The complication has been in design of the body. Something has to come apart for access to the bulb. I think my 1" heater well is a bit too narrow to be reaching into for that. So I have been looking at a 2-piece design sort of like some of the HIs. I also don't really like the idea of reusing wood screws/threads many times, so I want it to go together with threaded inserts or captive nuts. My first attempt worked but is a bit wonky. Was hard to drill straight by hand, but I will be able to use a drill press for the next design.
I think maybe the next one should have the heater cover screws coming in from the top hold it all together. But the space for screw heads gets pretty cramped with the 11mm OD heater cover, and 1" drilled heater well. I also found some nice hardwood plugs that can replace the cork, or maybe be used in a bottom-loading design, similar to the screw-in core from above.
Latest update, on this idea of an easily serviceable/long lasting halogen log. This one has a nice machined socket for the 10W halogen bulb, and is held together by just the 2 heater cover screws. Same 11mm/10mm heat island style cover, and square walnut body. I am pretty happy with the design overall. The bulb will eventually break, but it just requires 2 screws to be removed for replacement. And this shouldn't wear out the threaded inserts or bulb sockets for a very long time.
Mill-Max sent me a free engineering sample of the socket contacts I requested, along with some cool catalogs
. These press into the 2mm OD, 1.7mm ID SS tubing nicely. The insertion/removal force on the bulb is light much lighter than the formed contacts, and lighter/smoother than the G4 sockets. The bulb pin goes in a little less than halfway. No scratching of the nickel plating on the bulb pins, or sockets, after 10-20 cycles. I think they will hold up very well, could reccomend them to try out. But I still might prefer a plain SS tube with a formed socket, though, since this fully covers the bulb lead, and feels more secure.
Was able to use a small drill press for this body, which made a big difference in the quality, especially for the heater well. 2 4-40 (about M3) screws hold down the heater cover, and the top piece of wood, to the base, which contains the bulb socket/support tubes, threaded inserts, power jack and wiring. The center hole is 3/8", allowing the bulb to pass through the top piece. In the bottom piece, it is instead filled in with 3/8 walnut plug, which has 2 5/64" holes for the bulb tubes. This makes it easier to replace the sockets if needed, and much easier to crimp copper wires to the SS tubes for the jack connection.
There are some minor things I still don't really like. One is that the threaded inserts and the outer bodies of the pin sockets are brass, which is leaded. I don't think this is an issue, since the pin sockets are gold plated, and the threaded inserts are well away from the vapor path. Could be fixed by using the SS tube formed sockets, and SS nuts rather than brass inserts. The other thing is that getting the heater cover screws in is a bit fiddly-requires holding the tube carefully in place, while using a thin screwdriver to get the screws in. It could be easier if they went in from the bottom, into a tapped washer or something.
Parts used:
heater cover: 11mm OD, 0.5mm wall 304 SS tube https://www.amazon.com/dp/B099QMDZRY
bulb tubes: 2mm OD, 0.15mm wall 304 SS tube https://www.amazon.com/dp/B09R9B592L
bulb contacts: Mill Max 0303-0-19-15-26-27-10-0 (BeNi contact, press fit) https://www.mill-max.com/products/p...tacle-crimp-type/0303/0303-0-19-15-26-27-10-0 available at Mouser https://www.mouser.com/ProductDetail/Mill-Max/0303-0-19-15-26-27-10-0
bulb: https://www.amazon.com/dp/B09BC9NQGR
barrel jack: https://www.amazon.com/dp/B07MPS3QD8
screens: https://www.amazon.com/dp/B07QF5TLZV
2x2 (1.5inx1.5in) walnut about 4" overall length (from Home Depot) https://www.homedepot.com/p/Swaner-...lnut-S4S-Hardwood-Boards-08011636WA/318989598
M10 SS washer, 10.5mm ID 20mm OD (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=4122&cclcl=en_US
2x 4-40x3/4" pan head SS machine screw (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=828432&cclcl=en_US
2x 4-40 brass threaded insert for wood (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=3015&cclcl=en_US
3/8" walnut plug (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=412218&cclcl=en_US
Mill-Max sent me a free engineering sample of the socket contacts I requested, along with some cool catalogs
. These press into the 2mm OD, 1.7mm ID SS tubing nicely. The insertion/removal force on the bulb is light much lighter than the formed contacts, and lighter/smoother than the G4 sockets. The bulb pin goes in a little less than halfway. No scratching of the nickel plating on the bulb pins, or sockets, after 10-20 cycles. I think they will hold up very well, could reccomend them to try out. But I still might prefer a plain SS tube with a formed socket, though, since this fully covers the bulb lead, and feels more secure.
Was able to use a small drill press for this body, which made a big difference in the quality, especially for the heater well. 2 4-40 (about M3) screws hold down the heater cover, and the top piece of wood, to the base, which contains the bulb socket/support tubes, threaded inserts, power jack and wiring. The center hole is 3/8", allowing the bulb to pass through the top piece. In the bottom piece, it is instead filled in with 3/8 walnut plug, which has 2 5/64" holes for the bulb tubes. This makes it easier to replace the sockets if needed, and much easier to crimp copper wires to the SS tubes for the jack connection.
There are some minor things I still don't really like. One is that the threaded inserts and the outer bodies of the pin sockets are brass, which is leaded. I don't think this is an issue, since the pin sockets are gold plated, and the threaded inserts are well away from the vapor path. Could be fixed by using the SS tube formed sockets, and SS nuts rather than brass inserts. The other thing is that getting the heater cover screws in is a bit fiddly-requires holding the tube carefully in place, while using a thin screwdriver to get the screws in. It could be easier if they went in from the bottom, into a tapped washer or something.
Parts used:
heater cover: 11mm OD, 0.5mm wall 304 SS tube https://www.amazon.com/dp/B099QMDZRY
bulb tubes: 2mm OD, 0.15mm wall 304 SS tube https://www.amazon.com/dp/B09R9B592L
bulb contacts: Mill Max 0303-0-19-15-26-27-10-0 (BeNi contact, press fit) https://www.mill-max.com/products/p...tacle-crimp-type/0303/0303-0-19-15-26-27-10-0 available at Mouser https://www.mouser.com/ProductDetail/Mill-Max/0303-0-19-15-26-27-10-0
bulb: https://www.amazon.com/dp/B09BC9NQGR
barrel jack: https://www.amazon.com/dp/B07MPS3QD8
screens: https://www.amazon.com/dp/B07QF5TLZV
2x2 (1.5inx1.5in) walnut about 4" overall length (from Home Depot) https://www.homedepot.com/p/Swaner-...lnut-S4S-Hardwood-Boards-08011636WA/318989598
M10 SS washer, 10.5mm ID 20mm OD (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=4122&cclcl=en_US
2x 4-40x3/4" pan head SS machine screw (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=828432&cclcl=en_US
2x 4-40 brass threaded insert for wood (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=3015&cclcl=en_US
3/8" walnut plug (from Ace Hardware) https://shop.hillmangroup.com/ccrz__ProductDetails?sku=412218&cclcl=en_US
Thanks brainy! It passed its first test well 
and stood up to a very hot burn in at around 12.3V overnight. No visible oxide discoloration on the bulb tubes, pins, or contacts. While the heater cover and screens got that slight yellow tint. So it seems that system isn't getting too hot, like the cheap ceramic sockets did.
The wood plug is more heat resistant than the cork, and better mechanically, but isn't 100% airtight. I kind of liked the idea of sealing off the base so the airpath is isolated. So I put a small cork in the bottom of the same hole as the wood plug sits in, to back it up. Easy to do if you get it in before soldering. The cork/wood plug combination might work well for protecting any cork pieces used in logs/stems from heat or crumbling. Curious to try it with a larger cork and dowel, to fit a 1" hole. Could allow for a full heater assembly to slide into a simple tube wood body. I think that's kind of like how some of the HI's are? And some of bloke's earlier builds in this thread, though I can't see the pictures.
Another small tip I have is for cutting the tiny SS tubes without a dremel, and without crushing them. If you use a hacksaw, it binds up on the tube, since it's thinner than the tooth pitch. But if you cut backwards, it can be very gentle and leave the end pretty clean. Very quick and just needs a touch of the file to deburr the OD. The ID can be deburred with a drill bit, twisting by hand. Since this leaves the tube round, its easier to make into a socket that won't scratch the plating off of the bulb pins.
and stood up to a very hot burn in at around 12.3V overnight. No visible oxide discoloration on the bulb tubes, pins, or contacts. While the heater cover and screens got that slight yellow tint. So it seems that system isn't getting too hot, like the cheap ceramic sockets did.The wood plug is more heat resistant than the cork, and better mechanically, but isn't 100% airtight. I kind of liked the idea of sealing off the base so the airpath is isolated. So I put a small cork in the bottom of the same hole as the wood plug sits in, to back it up. Easy to do if you get it in before soldering. The cork/wood plug combination might work well for protecting any cork pieces used in logs/stems from heat or crumbling. Curious to try it with a larger cork and dowel, to fit a 1" hole. Could allow for a full heater assembly to slide into a simple tube wood body. I think that's kind of like how some of the HI's are? And some of bloke's earlier builds in this thread, though I can't see the pictures.
Another small tip I have is for cutting the tiny SS tubes without a dremel, and without crushing them. If you use a hacksaw, it binds up on the tube, since it's thinner than the tooth pitch. But if you cut backwards, it can be very gentle and leave the end pretty clean. Very quick and just needs a touch of the file to deburr the OD. The ID can be deburred with a drill bit, twisting by hand. Since this leaves the tube round, its easier to make into a socket that won't scratch the plating off of the bulb pins.
Been thinking about logs and halogen bulbs some more, and looking back at my heat transfer textbook, trying to understand what is happening in logs/other vapes. I think I found some interesting ideas/observations.
Anyone try using some high-power (AC) bulbs way below their rated voltage? This should shift a lot of the output to IR by lowering the filament temp. There are also screw-base type bulbs available, at least here in the US, which would be easy to replace. I think someone mentioned this earlier in the thread, for possibly using the 20 or 50 watt bulbs.
For example, something like https://www.amazon.com/dp/B00NLO3TN2 is 250W, 120V. So should run at at least 7W at 20V. It should be more than that, since the bulb is not ohmic, it has higher resistance at higher filament temp. If the filament is 3000K at the rated power, it should be about 1200K at 7W, which is a dim red hot, almost all IR. Glass is more opaque at those temps too, so it may help to keep the heat in. I guess this probably wouldn't be as viable for 220 or 240V bulbs/countries, though. I did a little experiment with my 10W bulb running on my power supply, and resistance increases about 6% per watt between 2-7W (while allowing time for the temp to stabilize). The current decreases during warmup and increases a bit during a hit.
It also seems like halogen/radiant heating gives a unique possibility for closing the loop on temp control. While it is not capable of heating the air significantly, it can apply heat directly to an opaque surface. And the surface is also the only place that heat transfer by convection can take place. I think that taking advantage of this could create a device that can keep up with changing draw rate, and heat up very quickly, while using power efficiently. Effectively, the need for high thermal mass to keep the heater surface temps up during a draw could be eliminated. Could be good for a portable.
Anyone try using some high-power (AC) bulbs way below their rated voltage? This should shift a lot of the output to IR by lowering the filament temp. There are also screw-base type bulbs available, at least here in the US, which would be easy to replace. I think someone mentioned this earlier in the thread, for possibly using the 20 or 50 watt bulbs.
For example, something like https://www.amazon.com/dp/B00NLO3TN2 is 250W, 120V. So should run at at least 7W at 20V. It should be more than that, since the bulb is not ohmic, it has higher resistance at higher filament temp. If the filament is 3000K at the rated power, it should be about 1200K at 7W, which is a dim red hot, almost all IR. Glass is more opaque at those temps too, so it may help to keep the heat in. I guess this probably wouldn't be as viable for 220 or 240V bulbs/countries, though. I did a little experiment with my 10W bulb running on my power supply, and resistance increases about 6% per watt between 2-7W (while allowing time for the temp to stabilize). The current decreases during warmup and increases a bit during a hit.
It also seems like halogen/radiant heating gives a unique possibility for closing the loop on temp control. While it is not capable of heating the air significantly, it can apply heat directly to an opaque surface. And the surface is also the only place that heat transfer by convection can take place. I think that taking advantage of this could create a device that can keep up with changing draw rate, and heat up very quickly, while using power efficiently. Effectively, the need for high thermal mass to keep the heater surface temps up during a draw could be eliminated. Could be good for a portable.
Flotsam
Well-Known Member
Those are some really interesting points. All of my halogen projects so far have centered on low DC voltages.
My question is conceptually about convection is about air movement. It seems every design relies solely on lung power. I always wonder if low pressure air pump might be the way to go.
@Flotsam: I think you may be right, and the Volcano, EQ, etc with the bags/fan follow that principle, though don't seem to be too popular now. Does anyone know whether there ever any fan powered portables? That could be an interesing approach, too. But I think most people, myself included, prefer the experience of a lung-powered device. Modeling heat transfer, especially by convection, can get really complicated, and I think that vaporizers almost defy it, with the wide range of effective designs, and transient nature of how they are used.
@Hippie I will have to try it out. I don't think the halogen cycle will be too important if the bulb is run cold. My understanding is that it is just a way of enabling the filament to run hotter without evaporating, so the bulb emits more in the visible spectrum. But if we avoid that anyway, the tungsten evaporation will be much slower.
@Hippie I will have to try it out. I don't think the halogen cycle will be too important if the bulb is run cold. My understanding is that it is just a way of enabling the filament to run hotter without evaporating, so the bulb emits more in the visible spectrum. But if we avoid that anyway, the tungsten evaporation will be much slower.
Flotsam
Well-Known Member
so i wanted to throw out a question. I have been looking for a good piece of wood to use for a log project like this.
My brother in law suggested this place https://hardwoodstore.com/ i want to go in person as he said they had good prices on scrap sizes which they have available. My brother in law bought a slab of live edge Olive wood 8 ' for an art project he is doing.
Looking through some stuff i have on hand i do have a ceramic piece i could use for a log. Not wood but it is a potential idea to try out. I am looking how i can repurpose some halogen heater parts i had been playing with. Its about 5 inches tall and 1 in internal diameter opening. Thoughts on ceramic? I have found ceramic easy to drill w glass bits.
My brother in law suggested this place https://hardwoodstore.com/ i want to go in person as he said they had good prices on scrap sizes which they have available. My brother in law bought a slab of live edge Olive wood 8 ' for an art project he is doing.
Looking through some stuff i have on hand i do have a ceramic piece i could use for a log. Not wood but it is a potential idea to try out. I am looking how i can repurpose some halogen heater parts i had been playing with. Its about 5 inches tall and 1 in internal diameter opening. Thoughts on ceramic? I have found ceramic easy to drill w glass bits.
Sounds cool to me. Glazed on the inside would be ideal I guess, to avoid any cleaning/dust coming off issues, but I wouldn't worry too much about it. 1in ID is what I used on my wood units with 11mm heater cover (~7mm gap), they get pretty warm on the outside but easily holdable. It's a bit tight to work in there when using screws to hold the heater cover down. If your halogen heater parts are larger, it may be tight to work in, get hotter on the outside, and/or require more watts. None of those needs to be a deal breaker. You could hold the heater cover in the ceramic with a drilled cork, or make a small wood puck for it to sit on, which fits tightly inside the ceramic.
What kind of halogen parts have you been playing around with? I'm always curious to see what has worked. Lots of the old threads here don't have the pictures anymore.
What kind of halogen parts have you been playing around with? I'm always curious to see what has worked. Lots of the old threads here don't have the pictures anymore.
Flotsam
Well-Known Member
Yes the ceramic is fully glazed inside and outside. It is a really nice shape.Sort of fatter in the middle.
Your idea is perfect for attaching heater to ceramic shell using a puck. I can attach the puck with sheet metal screws externally rather than inside like some of the wood designs although I guess that would work there too. I will have 2 additional holes for the 12 v leads. Mechanical clips to hold the wire to the halogen bulbs. I have one bulb type w reflector and another without. This would illuminate and more importantly head sort of a capsule w balls. The capsule is actually from a brass fitting. I am investigating brass over ss both for thermal properties & brass material is more easily machined over ss. The wire insulation currently is hi temp silicone although I have thought of using small diameter ceramic tubing as the insulators.
The overall concept is for this to be a table top device, 12 vdc power source which will initially be a lab supply. I am moving towards using Milwaukee 12 v batteries for piwer eventually. So a cannabis stem would be placed inside the ceramic log functioning as a heater. I was going to play around w a variety of arizer type stems that I have.
But will be studying the log designs for this.
Open to all suggestions as well as questions. There are tons of fascinating design elements just in this thread,
Your idea is perfect for attaching heater to ceramic shell using a puck. I can attach the puck with sheet metal screws externally rather than inside like some of the wood designs although I guess that would work there too. I will have 2 additional holes for the 12 v leads. Mechanical clips to hold the wire to the halogen bulbs. I have one bulb type w reflector and another without. This would illuminate and more importantly head sort of a capsule w balls. The capsule is actually from a brass fitting. I am investigating brass over ss both for thermal properties & brass material is more easily machined over ss. The wire insulation currently is hi temp silicone although I have thought of using small diameter ceramic tubing as the insulators.
The overall concept is for this to be a table top device, 12 vdc power source which will initially be a lab supply. I am moving towards using Milwaukee 12 v batteries for piwer eventually. So a cannabis stem would be placed inside the ceramic log functioning as a heater. I was going to play around w a variety of arizer type stems that I have.
But will be studying the log designs for this.
Open to all suggestions as well as questions. There are tons of fascinating design elements just in this thread,
Nice! Sounds like a cool build. What kind of clips for the bulb leads/wires? I looked around for crimp contacts but ended up being satisfied with using tiny SS tubes (2mm OD, 0.15mm wall) to hold the bulb. They support the bulb well and can run without insulation, low thermal conductivity so they stay pretty cool near the bottom of the heater cover.
Some may take issue with brass, and the lead content. I remain skeptical that it would be a major risk at the temperature range we deal with, but everyone has to draw their own line. The thermal conductivity is really good compared to SS. Though not as good as aluminum. Not sure how the machinability of lead-free compares to the leaded version. But I have to wonder if aluminum might be an improvement over brass on thermal conductivity, machinability and safety. Of course, this is moot if you are using the off-the-shelf fitting.
The arizer stems fit over the 11mm OD heater cover pretty well, or 7/16". The capsule and reflector bulb sound interesting. What wattage of bulb? Might need a lot of heat if there's a large surface area.
I have been quite satisfied with the 10w bulb, 11mm OD/0.5mm wall SS heater cover combination, I would suggest trying it out. I run it around 10-11V for 7-8 watts. Takes about 5 minutes to heat up fully. 1.5Ah battery could get you 2 hours or so of use. I've been thinking about a portable running on a 12V battery with a 50W bulb. Testing on my last log, full power can get the heater cover up to temp in only about 45 seconds, which seems better for battery use. I want to see if that can be pushed down further with a thinner heater cover
Some may take issue with brass, and the lead content. I remain skeptical that it would be a major risk at the temperature range we deal with, but everyone has to draw their own line. The thermal conductivity is really good compared to SS. Though not as good as aluminum. Not sure how the machinability of lead-free compares to the leaded version. But I have to wonder if aluminum might be an improvement over brass on thermal conductivity, machinability and safety. Of course, this is moot if you are using the off-the-shelf fitting.
The arizer stems fit over the 11mm OD heater cover pretty well, or 7/16". The capsule and reflector bulb sound interesting. What wattage of bulb? Might need a lot of heat if there's a large surface area.
I have been quite satisfied with the 10w bulb, 11mm OD/0.5mm wall SS heater cover combination, I would suggest trying it out. I run it around 10-11V for 7-8 watts. Takes about 5 minutes to heat up fully. 1.5Ah battery could get you 2 hours or so of use. I've been thinking about a portable running on a 12V battery with a 50W bulb. Testing on my last log, full power can get the heater cover up to temp in only about 45 seconds, which seems better for battery use. I want to see if that can be pushed down further with a thinner heater cover
Flotsam
Well-Known Member
Thanks for bringing up brass I have been researching this topic of brass safety for months. I wrote up something regarding this topic months ago for a different thread so i will copy that first:Nice! Sounds like a cool build. What kind of clips for the bulb leads/wires? I looked around for crimp contacts but ended up being satisfied with using tiny SS tubes (2mm OD, 0.15mm wall) to hold the bulb. They support the bulb well and can run without insulation, low thermal conductivity so they stay pretty cool near the bottom of the heater cover.
Some may take issue with brass, and the lead content. I remain skeptical that it would be a major risk at the temperature range we deal with, but everyone has to draw their own line. The thermal conductivity is really good compared to SS. Though not as good as aluminum. Not sure how the machinability of lead-free compares to the leaded version. But I have to wonder if aluminum might be an improvement over brass on thermal conductivity, machinability and safety. Of course, this is moot if you are using the off-the-shelf fitting.
The arizer stems fit over the 11mm OD heater cover pretty well, or 7/16". The capsule and reflector bulb sound interesting. What wattage of bulb? Might need a lot of heat if there's a large surface area.
I have been quite satisfied with the 10w bulb, 11mm OD/0.5mm wall SS heater cover combination, I would suggest trying it out. I run it around 10-11V for 7-8 watts. Takes about 5 minutes to heat up fully. 1.5Ah battery could get you 2 hours or so of use. I've been thinking about a portable running on a 12V battery with a 50W bulb. Testing on my last log, full power can get the heater cover up to temp in only about 45 seconds, which seems better for battery use. I want to see if that can be pushed down further with a thinner heater cover
There is an FYI that is on Reddit that addresses the safety of different materials. It also talks to the issue of material safety . There is something called the Material Safety Data Sheet (MSDS) that suppliers have to provide. Just google that and the material you are interested in and you can have fun for hours!
So to make Stainless Steel you need to have a small amount of chromium in there & that's why Stainless does not rust. But a lot of stainless steel is used in medical devices in general. So most stainless is considered safe. Similar for Brass, most brass musical instruments have used brass mouthpieces for centuries but people think that since lead is part of its alloy it is unsafe. Brass is used widely in plumbing world wide too. When you hear about lead pipes in drinking water its not the lead in brass that is the concern.
The thing you don't want to do is worry if you read something about toxic fumes at like 800 or 900 degrees for some material and worry about that, The internal temperatures in a Vaporizer doesn't come close to that.
I also think it is worth considering that so -called "safe" materials is put together with smoking in mind and somehow thinking the material might off gas or react with the smoke. When we are vaping materials we are not seeing temperatures anything close to when combusting. What we see manufacturers use in the chamber where vaporization occurs is glass, stainless steel, ceramic, aluminum and of course Gold (Nectar Hex). and if vapor comes into contact with something it is very sticky and not likely to adulterate the whole rest of the vapor produced.
So since that time i have additional points that i can add. I had an old brass pipe from years ago i used for smoking which is not really a great comparison since the taste and smell of burning cannabis overwhelms whatever brass smell might exist. Brass does have a very slight odor if you pick up a piece and smell it alone. What i have learned is this smell is not really the brass but the oil residue that your fingers leave on the metal. There is an experiment if you have two pieces of similar brass and handle one extensively and the other is left alone the handled piece will have a slight odor while the freshly cleaned one does not. In addition after a little time brass acquires a slight tarnish (oxidation) which will remain and lessen the impact of smell on handled brass.
But it does have a slight odor which i can mitigate in two ways . In some other design i line air passages with glass tubing so not so bad. Plus the basic premise is to limit the brass to roles where it is not in the primary air path and it is mostly in the heater. I have done some limited testing with this and pretty satisfied that brass is safe that i have vaped out of it.
I did mention that brass has been used for centuries in the musical instrument mouthpieces. Some people do have sensitivities to this and there is a gold mouthpiece upgrade that you can get. it seems for some people the salts in people's saliva to give them a slightly funny taste. The point i left out when i pointed that out originally is that with brass instruments you are almost entirely blowing out rather than sucking in air with a vaporizer.
You are right most people immediately think brass is unacceptable because they don't understand how alloys work. Its not like you scrape brass material and flecks of lead come off. To my knowledge almost all brass alloys contain this small amount of lead. I know there has been changes over the years with the solder that is used to connect brass and copper pipes together.
So i will continue to experiment with brass for my own projects and try to use the brass in the proper way. I am also trying to create side by side comparisons of using SS and brass to explore this as well. SS seems a lot harder to machine, but someone like Maremarinsing is the expert on that . (check out his Etsy store)
Don't have the specifics of the Halogen bulbs i have right now. Will follow up on that.
I'm with you on all that. I'm pretty sure that when people say they can "taste the metal", its the burnt off fingerprints, or whatever the degradation products from metal contact with skin oil, that are the real cause. At least in a convection device. I could maybe buy that there is some slight chance of catalytic terpene degradation or something, in a conduction oven, but I also have my doubts that this effect would have any significance relative to the burning fingerprint issue. That said, if you have to touch the metal parts to use the vape, and it gets hot, you will probably taste some of that bad flavor, so other materials can certainly be preferable for that reason.
I have noticed the fingerprints burning and causing dark deposits on the SS of dynavap caps. Also on logs, if the bulb or heater cover was touched by hand, I have seen vapors rising out when first powered on, with the same burnt/metallic smell. So I could definitely reccomend cleaning the parts well before with alcohol, and keeping them clean while assembling. It's already reccomended that you do not handle halogen bulbs without gloves or paper cover or something, as the fingerprints there can cause hot/cold spots on the glass, and even cause it to break.
I think there is some misunderstanding of phase change and concentration. Evaporation/sublimation of metal from solid to vapor can and does occur, even at vape temperatures or below. But this is only really a concern in high-vaccum environments, where the vapor pressure can become a significant fraction of the total pressure. Evaporation can also be a concern with molten lead, when people are casting etc, but that is a lot hotter. And dissolving it into drinking water is a whole different situation.
Let's just say for the sake of argument that you made a heater cover from elemental lead, and ran it at 300C (only about 25C below it's melting point). The vapor pressure is about 10^-12 bar. At atmospheric pressure, that's about 0.0086 micrograms per cubic meter. The EPA tracks airborne lead, which was mostly caused by leaded gas. The standard is to be below 0.15 micrograms per cubic meter, and the measured level in 2023 is well below that, at 0.026. So in this crazy hypothetical, the most amount of lead you could add to clean air is only about 1/3 of what is already there. Exposure through direct contact and ingestion would be a lot more concerning. https://www.epa.gov/air-trends/lead-trends https://www2.iap.tuwien.ac.at/www/surface/vapor_pressure https://digital.library.unt.edu/ark:/67531/metadc1185924/m1/3/ I am definitely not an expert on chemistry/thermodynamics, but I think looking to the high-vaccum applications can show us where there is a remote possibility of concern at our temp range and atmospheric pressure. Notice that the list of best materials for high vaccum overlaps very well with the list of materials generally seen as best for vapes: SS, titanium, alumina (aka sapphire, corundum, ruby) machinable ceramic (Zirconia etc), glass.
I'll be interested to see if you find any improvements with the better thermal conductivity of brass. I've been going back and forth on whether I think that it is necessary. It should be more important for thicker parts. You could try calculating the Fourier Number and Biot Number for the brass VS ss, and look at the Heisler Charts to see how much the temperature at the surface drops when hitting. I think that the success of ruby/sapphire over glass/quartz balls in ball vapes could be explained by the better thermal conductivity/diffusivity helping to keep the temps up. But the conductivity difference between ruby/glass (about 25-40 times) is bigger than brass/SS (about 7-10 times). But I don't know, this stuff seems pretty hard to model.
I have noticed the fingerprints burning and causing dark deposits on the SS of dynavap caps. Also on logs, if the bulb or heater cover was touched by hand, I have seen vapors rising out when first powered on, with the same burnt/metallic smell. So I could definitely reccomend cleaning the parts well before with alcohol, and keeping them clean while assembling. It's already reccomended that you do not handle halogen bulbs without gloves or paper cover or something, as the fingerprints there can cause hot/cold spots on the glass, and even cause it to break.
I think there is some misunderstanding of phase change and concentration. Evaporation/sublimation of metal from solid to vapor can and does occur, even at vape temperatures or below. But this is only really a concern in high-vaccum environments, where the vapor pressure can become a significant fraction of the total pressure. Evaporation can also be a concern with molten lead, when people are casting etc, but that is a lot hotter. And dissolving it into drinking water is a whole different situation.
Let's just say for the sake of argument that you made a heater cover from elemental lead, and ran it at 300C (only about 25C below it's melting point). The vapor pressure is about 10^-12 bar. At atmospheric pressure, that's about 0.0086 micrograms per cubic meter. The EPA tracks airborne lead, which was mostly caused by leaded gas. The standard is to be below 0.15 micrograms per cubic meter, and the measured level in 2023 is well below that, at 0.026. So in this crazy hypothetical, the most amount of lead you could add to clean air is only about 1/3 of what is already there. Exposure through direct contact and ingestion would be a lot more concerning. https://www.epa.gov/air-trends/lead-trends https://www2.iap.tuwien.ac.at/www/surface/vapor_pressure https://digital.library.unt.edu/ark:/67531/metadc1185924/m1/3/ I am definitely not an expert on chemistry/thermodynamics, but I think looking to the high-vaccum applications can show us where there is a remote possibility of concern at our temp range and atmospheric pressure. Notice that the list of best materials for high vaccum overlaps very well with the list of materials generally seen as best for vapes: SS, titanium, alumina (aka sapphire, corundum, ruby) machinable ceramic (Zirconia etc), glass.
I'll be interested to see if you find any improvements with the better thermal conductivity of brass. I've been going back and forth on whether I think that it is necessary. It should be more important for thicker parts. You could try calculating the Fourier Number and Biot Number for the brass VS ss, and look at the Heisler Charts to see how much the temperature at the surface drops when hitting. I think that the success of ruby/sapphire over glass/quartz balls in ball vapes could be explained by the better thermal conductivity/diffusivity helping to keep the temps up. But the conductivity difference between ruby/glass (about 25-40 times) is bigger than brass/SS (about 7-10 times). But I don't know, this stuff seems pretty hard to model.
Flotsam
Well-Known Member
You always have a lot of information to chew on. I will need to study up on few of these topics. Especially this last paragraph here.
I had impression brass had better suitability than ss at least for retaing heat. Would you say you halogen heater is somewhat similar to Highlighter?
I had impression brass had better suitability than ss at least for retaing heat. Would you say you halogen heater is somewhat similar to Highlighter?
Not really, I haven't done too much experimenting on that. My designs are all most similar to the Heat Island and DIY logs in this thread, as well as most other log vapes. @Alan and @blokenoname have written lots of good information on here, but I think the important characteristics are the low thermal mass of the heater, and operating power somewhere in the range of 7W, maybe 6-10. Highligher I think runs more like 15-20W. Both of them don't have temp sensing, they control temperature just by adjusting the power and giving enough time for the heater to reach a steady temperature. And stem-load a smaller bowl, like dynavap sized or smaller. Highlighter is a bigger, heavier hitter. The halogen doesn't really make any performance difference vs another heating element at the same power level, in this design. I just like that it is glass, replaceable, and gives a nice night-light effect.
On the thermal stuff, it's definitely a rabbit hole, been trying to understand it myself. The log design is quite impressive to me, I think it shows that a vaporizer doesn't need to be complicated to be effective. With the Heat Island and other modern logs specifically, it's also impressive that it performs so well with low thermal capacitance (short heat up time), relatively low draw resistance, low power consumption whether idle or in use, and lack of closed-loop temperature control.
Brass has a little bit lower thermal capacity than stainless, actually, both per unit mass and per unit volume. About 86% by volume, 80% by mass, for cartridge brass/304 at 300K. But that doesn't necessarily tell the whole story. Thermal conductivity is way more, over 7 times better for the same comparison. And also more than twice the conductivity of alumina, about 100 times more than glass, and about 1/4 of pure copper.
Whether that's important or not, would depend on the heater core design. There's not really any point in storing heat, if you can't transfer it to the air over the time scale of a hit. That's where the Biot and Fourier numbers come into play.
If the heater is "thermally thick", and has a low surface area to volume ratio, and/or low thermal conductivity, then the temperature can vary more within the material, and less within the air flowing over it. If it's "thermally thin", the surface area/volume ratio is higher, and the temperature variation happens more in the air flowing over it, and less within the solid. That's what the Biot number characterizes. If you multiply the convection coefficient, h (characteristic of the fluid, flow, and surface geometry), by a characteristic length L (thickness of a wall, or often just Volume/Surface area), and divide by the thermal conductivity of the solid, k, and cancel out the units, you get the Biot number Bi. If it's less than about 0.1, then it generally makes sense to model the object in question as a lumped capacitance - where the temperature thoughout it is constant. I think almost all vape materials and sizes will have Bi < 0.1, with the exceptions being thick glass or quartz with high-speed airflow. Assuming the convection coefficient is at most 250 W/m2-K, which is the highest end of what my textbook says is typical for air forced convection. Bi for the thickness of the heater cover (0.5mm) for 304 SS is 0.0084, really small. For a 3mm ruby, it would be about the same. But for a 3mm glass bead, it would be about 0.27. I think for vaping purposes its unlikely that any metal part will have Bi > 0.1. You would have to have a thickness of more than 6mm for SS. Glass is different, would be more like 0.6mm, if the convection is really strong.
The Biot number doesn't involve the time, or thermal capacity of the solid, though. Since vaporizers are transiently used, this is important. Using the vape is always going to drop the temp at the heater surface. The Fourier number can characterize about how long it will take for the heat stored within the heater to diffuse to the surface. Some of this heat is transferred straight though the material near the surface and to the air, but some of it it is stored, to get the surface temperature back up. Over short time scales t (small Fo) how much total thermal capacity you have doesn't really matter, since the conductivity isn't high enough for the heat deep within to get to the surface. How short exactly depends on the thermal diffusivity, alpha, and characteristic length L, which is used to calculate Fo = alpha * t / L^2. For the 0.5mm SS heater cover, Fo would be about 16 * time. For 3mm ruby, about 7 * time, and for 3mm glass only 0.37 * time. Looking at the heisler charts can show how much the temperature drops over a longer hit, and how much of the stored heat is used up.
This is all most applicable to vapes where the heat output all comes from the stored heat - wireless ball vapes would be the best example. But I think it is a good approximation for logs, where the heat output while hitting them should be way more than the power consumed. Consider that heating 1 liter of air from 20 to 220C, in 5 seconds, is about 50W.
I'm not completely sure about this stuff, but I think that this shows that brass is unlikely to improve performance by that much over an SS part with the same geometry. The conductivity is good enough to keep up with the amount of heat you can get out through convection, unless the heater is crazy thick. And the length of a hit is long enough that all the heat stored will be available at the surface. But this type of discussion might be better suited for another thread. Looking forward to seeing your build.
On the thermal stuff, it's definitely a rabbit hole, been trying to understand it myself. The log design is quite impressive to me, I think it shows that a vaporizer doesn't need to be complicated to be effective. With the Heat Island and other modern logs specifically, it's also impressive that it performs so well with low thermal capacitance (short heat up time), relatively low draw resistance, low power consumption whether idle or in use, and lack of closed-loop temperature control.
Brass has a little bit lower thermal capacity than stainless, actually, both per unit mass and per unit volume. About 86% by volume, 80% by mass, for cartridge brass/304 at 300K. But that doesn't necessarily tell the whole story. Thermal conductivity is way more, over 7 times better for the same comparison. And also more than twice the conductivity of alumina, about 100 times more than glass, and about 1/4 of pure copper.
Whether that's important or not, would depend on the heater core design. There's not really any point in storing heat, if you can't transfer it to the air over the time scale of a hit. That's where the Biot and Fourier numbers come into play.
If the heater is "thermally thick", and has a low surface area to volume ratio, and/or low thermal conductivity, then the temperature can vary more within the material, and less within the air flowing over it. If it's "thermally thin", the surface area/volume ratio is higher, and the temperature variation happens more in the air flowing over it, and less within the solid. That's what the Biot number characterizes. If you multiply the convection coefficient, h (characteristic of the fluid, flow, and surface geometry), by a characteristic length L (thickness of a wall, or often just Volume/Surface area), and divide by the thermal conductivity of the solid, k, and cancel out the units, you get the Biot number Bi. If it's less than about 0.1, then it generally makes sense to model the object in question as a lumped capacitance - where the temperature thoughout it is constant. I think almost all vape materials and sizes will have Bi < 0.1, with the exceptions being thick glass or quartz with high-speed airflow. Assuming the convection coefficient is at most 250 W/m2-K, which is the highest end of what my textbook says is typical for air forced convection. Bi for the thickness of the heater cover (0.5mm) for 304 SS is 0.0084, really small. For a 3mm ruby, it would be about the same. But for a 3mm glass bead, it would be about 0.27. I think for vaping purposes its unlikely that any metal part will have Bi > 0.1. You would have to have a thickness of more than 6mm for SS. Glass is different, would be more like 0.6mm, if the convection is really strong.
The Biot number doesn't involve the time, or thermal capacity of the solid, though. Since vaporizers are transiently used, this is important. Using the vape is always going to drop the temp at the heater surface. The Fourier number can characterize about how long it will take for the heat stored within the heater to diffuse to the surface. Some of this heat is transferred straight though the material near the surface and to the air, but some of it it is stored, to get the surface temperature back up. Over short time scales t (small Fo) how much total thermal capacity you have doesn't really matter, since the conductivity isn't high enough for the heat deep within to get to the surface. How short exactly depends on the thermal diffusivity, alpha, and characteristic length L, which is used to calculate Fo = alpha * t / L^2. For the 0.5mm SS heater cover, Fo would be about 16 * time. For 3mm ruby, about 7 * time, and for 3mm glass only 0.37 * time. Looking at the heisler charts can show how much the temperature drops over a longer hit, and how much of the stored heat is used up.
This is all most applicable to vapes where the heat output all comes from the stored heat - wireless ball vapes would be the best example. But I think it is a good approximation for logs, where the heat output while hitting them should be way more than the power consumed. Consider that heating 1 liter of air from 20 to 220C, in 5 seconds, is about 50W.
I'm not completely sure about this stuff, but I think that this shows that brass is unlikely to improve performance by that much over an SS part with the same geometry. The conductivity is good enough to keep up with the amount of heat you can get out through convection, unless the heater is crazy thick. And the length of a hit is long enough that all the heat stored will be available at the surface. But this type of discussion might be better suited for another thread. Looking forward to seeing your build.
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