Diameter of coils?

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93gc40

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Diameter of the coil has NOTHING to do with resistance or heatup time... That is all about wire diameter (gauge) and its resistance due to differing materials.
Basically at a given ohm rate say 1ohm a fatter wire will have a lower resistance and slower heatup time than a thinner wire regardless the diameter of the coil itself. That will affect wicking, heat concentraion and number of loops to the coil.
 

State O' Flux

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Welcome to ECF, Jblow...

I'm afraid you've been caught up in a dismally common misconception.

Coil ID ("diameter") has no bearing on resistance or heat capacity ("ramp up time") value. Only 3 things determine resistance for a new DIY heating coil.

1. Wire gauge or thickness.
2. Wire length.
3. Wire stretch - AKA the "tension" applied to the wire during coil manufacture.​

The physical shape of a coil - be it round, hex, stove top etc etc... and ID - from sub-micro to 3.5 or 4mm... does not affect resistance, other than if manufactured with tension sufficient to "stretch" the wire.

Used Kanthal A1 (iron/chromium/aluminum) coils can change resistance both downward... due to decay of the aluminum oxide, electrically insulative/heat conductive surface barrier layer, which - due to the exposure of the remaining iron/chromium content - may allow for wrap to wrap shorting with a compressed wrap coil... and upward due to resultant cross-sectional reduction.

A 88.8mm length of 26 gauge K/A1 wire or a 116mm length of 26 gauge Nichrome 60 (or any other resistance wire with known Ω/mm) will, at room temperature, have a point to point net resistance of 1.0Ω... regardless if it's straight, wrapped - or shaped into an outline of Marilyn Monroe. ;-)

To further your education, including dispelling of myths, lies and total BS... please take a few moments to click the three hyperlinks below.

Cheers
 

mcclintock

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    This is correct, but just coming from a thread on contact coils, heat concentration can still be varied, given a certain total heat and surface area (heat flux) to work with. Still, I think the difference in wicking will dominate the effect of different coil diameters. Larger contains more wick, allowing more juice but not necessarily better regulation. If the coil starts off wetter, plus more fluid is heated without vaporizing it, more heat will be needed to get it going, with possibly as much or more chance of burning later in the hit.
     

    93gc40

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    Unless I'm wrong he is asking if the diameter of a coil will change the total ohm value of a coil, which it will due to more or less total length of wire.

    NOT if the only factor changed is the coil diameter. A 1ohm piece of wire is going to be 1 ohm regardless of the shape or size coil you wind it to.
     

    bnitch

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    NOT if the only factor changed is the coil diameter. A 1ohm piece of wire is going to be 1 ohm regardless of the shape or size coil you wind it to.


    Think about that for a moment, if you make the coil smaller you have to take away some length of overall wire. And if you make it bigger you have to add wire to the coil. you can't do either without changing the resistance.
     

    Haadkoe

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    Think about that for a moment, if you make the coil smaller you have to take away some length of overall wire. And if you make it bigger you have to add wire to the coil. you can't do either without changing the resistance.


    But if you take a 2 inch piece of wire and make one big loop, or 10 small loops, the resistance stays the same so long as the overall length of the wire in question remains unchanged... As I understand it anyway.
     

    bnitch

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    But if you take a 2 inch piece of wire and make one big loop, or 10 small loops, the resistance stays the same so long as the overall length of the wire in question remains unchanged... As I understand it anyway.

    You are right, but the wire length won't stay the same from a 2.4mm to a 2.8mm coil, is all I'm saying.
     

    Brandon David

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    Bnitch is correct. Wrap 10 wraps of 26g on a 2mm mandrel and 10 wraps on a 3mm mandrel. The circumference of a coil directly relates to its resistance as long as it is the same number of wraps of the same gauage of the same type of the same wire.


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