Microcoil - Ohms seem too high?

[Chez]

I've recently started rebuilding my protank heads with microcoils built around a 1/16 drill bit using cotton ball strands for wick.

I'm doing between 8-11 wraps of 32awg Kanthal, tightly coiled and am finding the coils measure at between 4.8-5.6 Ohms, according to my zmax v3 (which seems to be reasonably accurate with pre-built coils).

Because of this I'm having to run them at 5-6v.

The vapor and flavor are great, I'm just surprised they are coming in this high, based on what others are getting in the microcoils/ohms thread when wrapping around a 1/16 drill bit.

Could it be the extra wire needed to feed down into the base of the head or that I'm wrapping them too tightly (each wrap is touching the next) or what? (Or should I just not worry and keep on vaping as its working well?).

Thanks in advance!

 

[sawtoothscream]

sounds about right for 32ga, try 30 or 28ga

I use 28 for my micros

 

[dirquist]

Wow, 32guage seems like too thin a wire. I dont know a ton on the subject but I make my micro and nano coils with either 28g or 30g Kanthal. I just did an 10/11 wrap nano coil (30g) I made on a syringe needle and it came out at 1.6ohms, which is almost perfect for me. Maybe one more wrap and it would be perfect. Im not too shocked to hear that it would be that high with 32g but Ive only tried a few different configurations so far and none with 32g. Im interested to read what the pros with micro coils have to say

 

[Chez]

Thanks guys. I actually have some 28 and 30 coming this week, so will give that a go. 32 was all I could get locally.

As I said, it's working REALLY well, I'd just rather run it a bit lower/have more voltage headroom. Also, my wife can no longer use my tanks as she uses a spinner which maxes out at 4.something volts!


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[sawtoothscream]

Wow, 32guage seems like too thin a wire. I dont know a ton on the subject but I make my micro and nano coils with either 28g or 30g Kanthal. I just did an 10/11 wrap nano coil (30g) I made on a syringe needle and it came out at 1.6ohms, which is almost perfect for me. Maybe one more wrap and it would be perfect. Im not too shocked to hear that it would be that high with 32g but Ive only tried a few different configurations so far and none with 32g. Im interested to read what the pros with micro coils have to say

I made a few with 32, they all sucked.

 

[williebb123]

Wow, 32guage seems like too thin a wire. I dont know a ton on the subject but I make my micro and nano coils with either 28g or 30g Kanthal. I just did an 10/11 wrap nano coil (30g) I made on a syringe needle and it came out at 1.6ohms, which is almost perfect for me. Maybe one more wrap and it would be perfect. Im not too shocked to hear that it would be that high with 32g but Ive only tried a few different configurations so far and none with 32g. Im interested to read what the pros with micro coils have to say

dirquist i thought you were one of the pro's ( long time no see man)

 

[ScottP]

Something doesn't sound right there. Using 32AWG Kanthal you would have to use a wire length of 4 3/16 to get to 4.8 ohms and a length of 4 7/8 to get 5.6ohms. Wrapping that around a 1/16th diameter, you would need 18-22 wraps leaving 1/4 inch long legs. 8-11 wraps should only be between about 2.4 and 3.2 maybe less depending on leg length.

I calculated this with the tool in my signature, but you can double check my math if you want. 32 gauge Kanthal A-1 is 1.15 ohms per inch.

 

[super_X_drifter]

I like to use 30 ga for a 2ish ohm setup. I like to wrap around molds that are 1/16" diameter or slightly less and all the wraps are touching each other or damn close. If my memory serves me correctly, it is around 14 wraps.

Conversely, I also like to use 27 ga for 1ish ohm setups. Wrapping around the same diameter mold as mentioned above, 10 or 11 wraps produces a setup with dual personalities for my typical vape style - here's how:

I typically fire and vape simultaneously. My hits are about 3 seconds long. This produces a vape just like the 2ish ohm 30 ga = Marlboro light.
Like this:

If I fire for 3 seconds before hitting then continue to fire while taking the 3 second hit it is a very different vape = hotbox Marlboro red. Sometimes I like a nice hot juicy hit

Keep in mind that I only build true micro coils = micro diameter (1/16" or slightly less) and all wraps touching - like this - that's 27 ga

 

[sawtoothscream]

Something doesn't sound right there. Using 32AWG Kanthal you would have to use a wire length of 4 3/16 to get to 4.8 ohms and a length of 4 7/8 to get 5.6ohms. Wrapping that around a 1/16th diameter, you would need 18-22 wraps leaving 1/4 inch long legs. 8-11 wraps should only be between about 2.4 and 3.2 maybe less depending on leg length.

I calculated this with the tool in my signature, but you can double check my math if you want. 32 gauge Kanthal A-1 is 1.15 ohms per inch.

I made one with 32ga, cant remember how many wraps, want to say 10-12 but it was around 5 ohms I used a 1/16th bit for that build.

 

[dirquist]

dirquist i thought you were one of the pro's ( long time no see man)

Hey ya, for whatever reason our paths have not crossed in a while. Good to see you still around

I can admit my weakness and dont want to pretend I am experienced and can properly help people when I cant. If we shift this to genesis or even silica/nextel I think I could be pretty darn helpful but I just started trying out micro/nano coils and am just learning myself. So far so good though. I like to use my vapesafe pipes which require a higher ohm coil and these really hit the spot for them.

Besides all that, Im not into sub ohm anymore so the extreme vapers have passed me by a little bit. I guess Im just getting old and Im perfectly satisfied with a "normal" amount of vapor lol.

 

[ScottP]

I made one with 32ga, cant remember how many wraps, want to say 10-12 but it was around 5 ohms I used a 1/16th bit for that build.

Sounds to me like some of the devices are adding a significant amount of resistance themselves. I mean otherwise the math just doesn't add up.

A Diameter of 1/6 (.0625") means the coil has a circumference of .0625 x 3.14159 (Pi) = 0.196349375, which we will round to 0.196

Wrapping your wire around that 12 times means the length would be 12 x 0.196 = 2.352 inches.

Now assuming you also had leads to the post of a full 1/4 inch (0.25) (which is kind of long) that would add a half inch (0.25 x 2) of wire making the total now 2.852 inches in length.

Since Kanthal A-1 32gauge is 1.15 ohms per inch, you coil and leads should be measuring 1.15 x 2.852 = 3.2798 rounded to 3.3ohms.

If you got 5ohms out of that, then your device has to be adding about 1.7ohms to your build.

 

[Chez]

Sounds to me like some of the devices are adding a significant amount of resistance themselves. I mean otherwise the math just doesn't add up.

A Diameter of 1/6 (.0625") means the coil has a circumference of .0625 x 3.14159 (Pi) = 0.196349375, which we will round to 0.196

Wrapping your wire around that 12 times means the length would be 12 x 0.196 = 2.352 inches.

Now assuming you also had leads to the post of a full 1/4 inch (0.25) (which is kind of long) that would add a half inch (0.25 x 2) of wire making the total now 2.852 inches in length.

Since Kanthal A-1 32gauge is 1.15 ohms per inch, you coil and leads should be measuring 1.15 x 2.852 = 3.2798 rounded to 3.3ohms.

If you got 5ohms out of that, then your device has to be adding about 1.7ohms to your build.

The only flaw I can see in that logic is that the 1/6" is the inner diameter, meaning every wrap is a little larger/longer than that.. But only marginally.

As for the device adding to it - I don't understand how it can be when it reads all of the pre-built ones I buy to +/- 0.2 ohms (which I'm guessing is manufacturing variance).

I'm wondering if its something to do with the fact all the coils are touching or some kind of interference/interaction with the inner diameter being so small and the wires being close to each other.

I'm honestly just speculating here.. I don't understand the science behind it perfectly.


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[Crash Moses]

I just made a quick test coil. 10 wraps of 32 awg Kanthal around a 1/16 drill bit with long legs came out to 3.07 ohms.

Are your coils touching? They should be...if not you may need to compress them with a pair of needle nose pliers and apply some heat. They should look similar to Supes pictures above.

Do you have pictures of the coil? That might help figure it out.

 

[ScottP]

The only flaw I can see in that logic is that the 1/6" is the inner diameter, meaning every wrap is a little larger/longer than that.. But only marginally.

As for the device adding to it - I don't understand how it can be when it reads all of the pre-built ones I buy to +/- 0.2 ohms (which I'm guessing is manufacturing variance).

I'm wondering if its something to do with the fact all the coils are touching or some kind of interference/interaction with the inner diameter being so small and the wires being close to each other.

I'm honestly just speculating here.. I don't understand the science behind it perfectly.


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The bottom line is that to get 5ohms from 32gauge Kanthal you have to use 4.35 inches of wire. So just for an experiment, I just cutoff a piece of 32gauge Kanthal to that exact length, and wrapped it around a 1/16" nail, leaving legs slightly longer than 1/4" it took 15 wraps. So either the wrap count was off by 3 or 4 wraps, the legs on the coil were really long, or something else is going on.

 

[ScottP]

I just made a quick test coil. 10 wraps of 32 awg Kanthal around a 1/16 drill bit with long legs came out to 3.07 ohms.

That math adds up properly.

 

[Chez]

I think maybe my wrap count was off.. I'll check with my camera and macro lens in a few..

I managed to get hold of some 30awg kanthal and made a 10-wrap microcoil and it meters at 1.9 ohms, which seems far more reasonable.


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[ScottP]

I think maybe my wrap count was off.. I'll check with my camera and macro lens in a few..

I managed to get hold of some 30awg kanthal and made a 10-wrap microcoil and it meters at 1.9 ohms, which seems far more reasonable.


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Yep that math adds up too.

 

[Aal_]

Friends, staying on the same topic, does this mean it is impossible to have a 1 ohm coil with 32 gauge wire? scrottP can you make the calculations for me to get 10 wraps what is the diameter i want to use (I think it would be super nano, like pico)? lol (sorry not meaning to highjack the thread but interesting info for people who don't have gauges less than 32-30)

 

[DoogieTony]

Friends, staying on the same topic, does this mean it is impossible to have a 1 ohm coil with 32 gauge wire? scrottP can you make the calculations for me to get 10 wraps what is the diameter i want to use (I think it would be super nano, like pico)? lol (sorry not meaning to highjack the thread but interesting info for people who don't have gauges less than 32-30)

Thats just not going to work well with 32ga. The main reason micros work so well is because of the surface area contacting the wick. You also need enough wick to supply juice to the coil so there's a limit to how small you can go.

30ga is do-able but won't be great, probably about 6 wraps 1.4mm I.d.

If you're shooting for 1ohm you should really get thicker wire.

 

[ScottP]

Friends, staying on the same topic, does this mean it is impossible to have a 1 ohm coil with 32 gauge wire? scrottP can you make the calculations for me to get 10 wraps what is the diameter i want to use (I think it would be super nano, like pico)? lol (sorry not meaning to highjack the thread but interesting info for people who don't have gauges less than 32-30)

Yeah, not going to work with 32 gauge. To get 1 ohm you can only use 7/8 of an inch. That would get you about 2 wraps. With 30 gauge you could get about 5 wraps assuming you are wrapping a 1/16 diameter coil. You might could get one more wrap if your legs are less than 1/4 inch.

To get 10 wraps at 1 ohm around a 1/16 diameter bit, you are going to need 28 gauge. Even then depending on leg length it might be slightly higher than 1.0 like maybe 1.1 Then again when doing macros the goal isn't usually low ohm.