Log vape resistors - My DIY Log Vape

[lazylathe]

@lazylathe - looks very nice. Also looks like your design would allow attaching a digital BBQ thermometer without the probe being in the vapor air path. i got the ones i use from Alibaba for about $5 each (10 quantity). it sure is nice to KNOW the temperature the heater is working at.

@Hippie Dickie Thanks for that, sound like a great integration project!
Not quite sure how i would place the probe so that it is not in the air path?
Unless it is attached to the outside of the heat tube but then it is not really measuring the air temp.

 

[Hippie Dickie]

Unless it is attached to the outside of the heat tube...

that should work fine. the air won't be hotter than the heater. and if the air flow cools the heater, you'll see it. looks like you have a lot of thermal mass.

 

[lazylathe]

Update time!
And not a good one...

I went to pick up the vape for modifications and found this when i took it apart!!

Discoloration in the wires and a resistor that is cracking in the middle section!!
Not what i was hoping to see after such short usage.

Looking into other options at the moment.
I have a few Stainless Steel heater cores on order and am in communication with a Chinese manufacturer of ceramic igniters that they can customize to what i need.

More updates when the parts arrive!

 

[natural farmer]

Update time!
And not a good one...

I went to pick up the vape for modifications and found this when i took it apart!!

Discoloration in the wires and a resistor that is cracking in the middle section!!
Not what i was hoping to see after such short usage.

Looking into other options at the moment.
I have a few Stainless Steel heater cores on order and am in communication with a Chinese manufacturer of ceramic igniters that they can customize to what i need.

More updates when the parts arrive!

That seems common with most log vapes AFAIK... The cracks are just on the enamel coating. Won't affect anything. No worries about it. And the discoloration is probable some burnt oils since slight blowbacks of vapor are not uncommon when hitting it... Great work so far!

 

[lazylathe]

Good to know thanks!!! But i still don't like it!

I will update with what i find out about having some custom made ceramic heaters.

 

[Hippie Dickie]

can you upgrade to a larger wattage resistor? maybe ceramic without an overcoat?

 

[vap999]

can you upgrade to a larger wattage resistor? maybe ceramic without an overcoat?

Yes, as I noted before (above), consider using a heavier-duty resistor, such as in the 7.5-8 ohm range. Perhaps, look for something like Ohmite 35J7R5 (high-energy, wire wound), ideally RoHS compliant (presuming you will be powering this with either a variable power supply or some type of digital temperature control, otherwise it will likely run too hot, get combustion, if fed full 12 volts).

Another problem is that any resistor is surely going to run hotter than needed (die early), and your heating will be inefficient, without good contact with your heat sink/exchanger. The resistor body needs to be up against metal, both to better heat the heat exchanger and cool the resistor (keep it in a normal operating range). There are many ways you could mount or press the resistor to the pipe/heat exchanger.

 

[lazylathe]

More work to do this weekend!

I will also look into some bigger resistors, thanks!

How would i go about figuring out what resistor to use with this wall wart?
Input - 120 VAC
Output - 12 VAC
Output current - 1000 mA

 

[Hippie Dickie]

ohm's law (v = i * r) is a start, but that is theoretical. the current flow through the resistance wire determines the temperature. if you don't know the gauge of the nichrome wire in the resistor, you will have to test and measure -- empirical. i gave up on ohm's law after about 5 years of frustration.

you just need a resistor with more wattage, rather than necessarily change the resistance (ohms), so the heat doesn't destroy the device.

and like vap999 says, a variable voltage power supply.

and you will get better performance if the power supply can output more amps (so higher wattage rated resistor). else, the recovery from air flow cooling takes too long.

 

[lazylathe]

I am thinking that if i design the heat core differently so that the resistor is in close contact with the tube that may alleviate some of the problems.
Thanks @vap999 for that suggestion!

Also simplifying the design so there is not so much tap and die use!
Just one tap to thread the power jack and then have the heat tube a press fit into the base.

Looking at resistors hurts my poor head...

So far i have had no luck with the ceramic heater cores... Language barrier with the Chinese manufacturers can be trying at times.
Should have the SS ones in about two weeks time to try out.
Also have a sample of a ceramic core on the way but i think it is too long, it will need a bigger vape body which may not be a bad thing.

 

[stickstones]

The stem also needs a redesign, version 2 will have it slip over the heat tube and not into it and if i remember to machine a stop for the screen that would be a bonus!

If I'm reading you right, this won't work. Won't you be compressing the herb in the packed bowl?

 

[lazylathe]

If I'm reading you right, this won't work. Won't you be compressing the herb in the packed bowl?

What i was thinking was this:
In version 1 i had the stem slide into the heat tube and it limited how close i got to the core.

In version 2, i am hoping to slide over the heat core so that i can shorten the heat tube considerably and therefore get the herb closer to the heat core. This way i would hope to be able to control the heat better by being able to get closer to the core initially and then move further away if i need cooler vapour.

May not work as planned but i will test it!
I don't want to copy everything...

 

[lazylathe]

Alright!
Version 2.something is warming up as i type!

Things i have discovered:
* The thinner the tube, the hotter it gets
* Heat sinks are not required for this design, they suck too much from the resistor and recovery time is longer between hits.
* The resistor does not need to touch the tube, actually seems to work better when not touching the tube
*The screen can be placed right on top of the resistor, want it as close to the herb as possible so that you can start anywhere, from hot to cooler vapor.
* Need to redesign the bowl, i have it too thick at the moment and it acts as a heat sink
* Managed to shrink the size down a lot!
* Still undecided about a liner to protect the wood?
* Looking into stainless steel tubing instead of aluminum, just need to find the right sizes to minimize machining steps.
* also need to research standard sizes for screens, glass adapters etc...

My friend tried it out last night and it worked pretty well, he was happy!
I am sure if i can lower the thermal mass a lot it will perform a lot better!

@stickstones Forgot to mention that this is how the E-Nano functions. The glass stem slides over the heat tube.

 

[Hippie Dickie]

* Looking into stainless steel tubing instead of aluminum, just need to find the right sizes to minimize machining steps.

or you can use stainless steel foil or thin sheet. form a cylinder and overlap the edges. i get 0.010" ss at r/c hobby shop in 8"x10" size. minimum thermal mass.

 

[lazylathe]

or you can use stainless steel foil or thin sheet. form a cylinder and overlap the edges. i get 0.010" ss at r/c hobby shop in 8"x10" size. minimum thermal mass.

I was thinking about that as well!
I have a 6 foot roll of SS shim stock that is 0.004 thick or 0.102mm thick.
I was thinking it would be pretty hard to do, but now i will give it a go!
Thanks Hippie!!

 

[Hippie Dickie]

my piece is 2" wide by 4" long. i wrap it around a 1" dowel to get the initial form, then deform to fit the space inside my cube. i have 90° tabs on the bottom edge to fit into a groove in the wood, inside wall of the cube.

 

[lazylathe]

my piece is 2" wide by 4" long. i wrap it around a 1" dowel to get the initial form, then deform to fit the space inside my cube. i have 90° tabs on the bottom edge to fit into a groove in the wood, inside wall of the cube.

I remember seeing them when i read your Bud Toaster thread now!
Maybe also a tab at the top to hold everything together evenly?

 

[lazylathe]

Doing some more thinking, which can be dangerous!

What if i used a Teflon disc instead of metal?
I can tap it and thread the jack directly into it and have the heat tube a push fit into the base.
That would decrease the thermal mass by a lot!

 

[Hippie Dickie]

reducing the thermal mass is only good if you have active heat recovery. otherwise the heat loss per toke is greater and recovery is longer.

teflon, meh ... i'm a member of the "just say no to plastic" cult.

 

[Alan]

lazylathe - You have been discovering the same things I have found. The resistor is really what is doing most of the air heating. The less metal you have the better. Thermal mass is important when using glass as the heating source since it can't hold as much as metal. I have gone to the least amount of metal as possible in my latest core design. The center tube is all that is really needed. Supporting it so that it doesn't take too much heat away is the real challenge. I would definitely avoid using teflon or any other materials that might be hazardous. Just metal and wood is really all that is needed. The simpler you can make it, the better. I wouldn't give up on the standard log vape resistor just yet. It appears that it was just given too much voltage. Anything over 14 volts for too long can easily damage the vitreous enamel coating. Hazy came up with a great way to keep the resistor centered in the tube. He wraps the top wire around the resistor rather than just bending it straight down. The air flow is more uniform/consistent around the resistor that way. It also acts as a spring to prevent thermal shock on the resistor.
Finding the right screen for the glass adapter can be a real challenge. I ended up hammering 3/8" screens until they are 10mm so that they will work. You may even need to punch them yourself. I got some punches at the leather store for making some of mine. I have found that a wood roasting bowl will remove less heat than silicone, glass, or metal so more is available for roasting.
Happy tinkering. Fun to be able to make your own vaporizer.

 

[lazylathe]

Thanks Alan!!
All your help has been invaluable in this journey!
My friend and i are both very appreciative and the results are starting to show.

For me it seems that there are too many varying opinions out there on how to build a vape, most of them are just basic theory though with very little to no practical experience.

I have rolled a very thin (0,004") SS tube and laser welded it together at work, it turned out very nice and looks like a viable way to make the heat tube. The joint is extremely strong as it actually melts the metal together for a permanent bond. I just need to figure out how to weld a screen in.

When i have a good sample to show i will take some pictures.
Off to look for stainless mesh to make screens from!

 

[natural farmer]

Thanks Alan!!
All your help has been invaluable in this journey!
My friend and i are both very appreciative and the results are starting to show.

For me it seems that there are too many varying opinions out there on how to build a vape, most of them are just basic theory though with very little to no practical experience.

I have rolled a very thin (0,004") SS tube and laser welded it together at work, it turned out very nice and looks like a viable way to make the heat tube. The joint is extremely strong as it actually melts the metal together for a permanent bond. I just need to figure out how to weld a screen in.

When i have a good sample to show i will take some pictures.
Off to look for stainless mesh to make screens from!

Why don't you try the screens @hazy is making for the Hot Pod? Easy to install and remove if needed and are very steady...

 

[lazylathe]

Why don't you try the screens @hazy is making for the Hot Pod? Easy to install and remove if needed and are very steady...

Thanks for that Natural Farmer!
That will be great fro herb screens for the stems!
I also need to make some flat screens for the heat tube to protect the resistor from any stray herb.

 

[natural farmer]

Thanks for that Natural Farmer!
That will be great fro herb screens for the stems!
I also need to make some flat screens for the heat tube to protect the resistor from any stray herb.

The Pod has the same screens for the heat tube... Never had specs of herbs in there. Why weld a screen when you can do that? It does the same job.

 

[lazylathe]

Version 3 is now rocking the house!

Removed the bulky aluminum heater core and replaced it with a 0,004" stainless steel sheet.
WOW, what a difference it makes!!
It heats up quicker and retains heat better.
Cloud size has increased about 5 fold as well!

Just have to be really careful as it reaches combustion temps quickly.
I will try bigger air inlet holes and also a slightly larger diameter heat tube.

Version 4 is sporting a glass heat tube.
Flavour is much improved and tastes pretty good to me!
Thinking the final version will have the glass heat tube, just a bit worried that it may break.
I can have custom made ones, so that is also an option.