Novice at coil building. Trying to understand the basic rules of thumb

[BLUwazoo]

So, just went to a coil building class and built my first coil, with people watching me every step of the way. Looking at build #2 and just want to make sure that I understand the basic rules of thumb. Please correct me if I'm wrong on any of this, because I am SO green.

So, as I understand it:

1. The smaller the gauge # the bigger the wire. (i.e. 28 is bigger wire than 30)
2. The bigger the wire (the smaller the gauge), the lower the resistance per a given length of wire.
3. The bigger the size of the coil itself, the lower the resistance, because there is more wire. (Not totally sure on this one.)
4. If you are combining coils, you would divide by the number of coils to get the overall ohm rating. (i.e. Two coils at 1 ohm = .5 ohm.)
5. Once the coil is put together and you fire it and mash the wire together so the coils are all touching, this makes it a "micro coil."
6. Once you do this the ohm rating of the coil changes. (As I recall, it went up slightly, like about .2 ohm.)

So, for my second coil, I'm going to shoot for about 1.5 for a dual coil on my Igo-W. My eLeaf iStick won't fire below one ohm. That means I need to try to build two identical coils at 3 ohm each. I'm going to use the middle size pin that's in my new coil jig, which should be about the size of the mini-screwdriver that came with the Igo. Would you say that 10 to 12 wraps of 30 kanthal, will get me to 3 ohms? If not, what would you recommend changing?

Thank you in advance for you help!

 

[Towmotor]

You appear to have it down except you are mixing up high/ low resistance. 1.0 ohms is less resistance than 2.0 ohms.
So in answer to your questions, smaller gauge wire has higher resistance and a larger ( greater mass) coil also has higher resistance.

Check out this link for some very handy coil wrapping calculations.

Coil wrapping | Steam Engine | free vaping calculators

 

[BLUwazoo]

You appear to have it down except you are mixing up high/ low resistance. 1.0 ohms is less resistance than 2.0 ohms.
So in answer to your questions, smaller gauge wire has higher resistance and a larger ( greater mass) coil also has higher resistance.

Check out this link for some very handy coil wrapping calculations.

Coil wrapping | Steam Engine | free vaping calculators

Thank you for the help! That calculator program is incredible! That is just what I need to start practicing my coil building!

Much appreciated Towmotor!

 

[Towmotor]

My pleasure. Good luck.

 

[Lessifer]

1. Yes, 28g is thicker than 30g
2. Yes, 28g has lower resistance per foot than 30g
3. No, a larger coil usually means it is a longer piece of wire, so it will have higher resistance. A 10 wrap coil will be higher ohm than a 9 wrap, with all other things being equal.
4. Yes, add up the resistance of the coils, then divide by the number of coils, for dual coils.
5. Kind of, a "contact" coil is one where all of the coils are touching, they can be tweezed together or wrapped touching or both. A "micro" coil is a contact coil with an inner diameter of 1/16" or less, below 1.2mm it's a "nano" and above 1/16" it's a "macro"
6. It can, but that's usually a product of some of the coils having previously shorted on each other, and then no longer being shorted, the actual resistance per inch of the wire does not change.

 

[BLUwazoo]

1. Yes, 28g is thicker than 30g
2. Yes, 28g has lower resistance per foot than 30g
3. No, a larger coil usually means it is a longer piece of wire, so it will have higher resistance. A 10 wrap coil will be higher ohm than a 9 wrap, with all other things being equal.
4. Yes, add up the resistance of the coils, then divide by the number of coils, for dual coils.
5. Kind of, a "contact" coil is one where all of the coils are touching, they can be tweezed together or wrapped touching or both. A "micro" coil is a contact coil with an inner diameter of 1/16" or less, below 1.2mm it's a "nano" and above 1/16" it's a "macro"
6. It can, but that's usually a product of some of the coils having previously shorted on each other, and then no longer being shorted, the actual resistance per inch of the wire does not change.

This is very, VERY helpful information. THANK YOU VERY MUCH!!!!!

 

[Lessifer]

You're welcome post some pics once you get some builds you'd like to show off or have questions about.

 

[BLUwazoo]

3. No, a larger coil usually means it is a longer piece of wire, so it will have higher resistance. A 10 wrap coil will be higher ohm than a 9 wrap, with all other things being equal.

I was referring to the inside diameter of the coil. In other words, 10 wraps at 2.5 mm. vs. 10 wraps at 2 mm. Which one would have less resistance?

 

[Lessifer]

I was referring to the inside diameter of the coil. In other words, 10 wraps at 2.5 mm. vs. 10 wraps at 2 mm. Which one would have less resistance?

Same gauge wire, same number of wraps, the one with the smaller ID will have less resistance because it will use a shorter length of wire.

 

[Lessifer]

The thing about true micro coils that I love is that you get a sharing of the heat through the wick. This effect is diminished as you go larger ID.

 

[BLUwazoo]

Got it! Again, thank you so much for the helpful guidance!!!