ABC coil making

[dakrido]

Hi all,
Because I often get confused reading different post on coil making, i decided to start a topic to hopefully get my questions answered.
I'd like to make a low ohm coil. I found this chart is for A1 type of Kanthal wire per inch, but it doesn't tell me everything...

30 awg (Ω/in) 0.7 ohms
31 awg (Ω/in) 0.9 ohms
32 awg (Ω/in) 1.2 ohms
33 awg (Ω/in) 1.4 ohms
34 awg (Ω/in) 1.8 ohms
35 awg (Ω/in) 2.3 ohms
36 awg (Ω/in) 2.9 ohms

When i wanted to order the kanthal at themeshcompany.com it gives as a reference SWG, and not as AWG. Anyone knows what the difference is?

Now the difficult part, how many wraps, which width of silica, and what size of kanthal gives me 1.2 ohms and... And how-come so?
Could someone can give me the math and logic that leads to the result i wanna get?



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[eHuman]

Obviously the length/gauge of the kanthal used ultimately determines the final Ω. The primary tool I would recommend to anyone diving into RBAs is an inexpensive multimeter.

Generically I recommend:
28g for <1.1Ω coils
30g for 1.1-1.8Ω coils
32g for >1.8Ω coils

My reason for these ranges is so you don't end up with too few or too many wraps needed to reach your desired target Ω.

A 30g 4/5 wrap coil should come close to hit your target, depending on wick diameter. I double up 2.5mm silica in my IGO-L.

 

[TomCatt]

Check out the PV Web Apps link in my signature. There's a calculator on the page that can give a general idea of a coil's resistance with a certain size wick used with a specific gauge resistance wire. Just keep in mind that the answers that this calculator gives are for an 'ideal system' - perfectly formed coil with evenly spaced wraps around a constant internal diameter; which is hard to achieve in the real world.


Chart with AWG (American Wire Gauge) and corresponding SWG (Standard Wire Gauge) - Wire Gauge Reference Table