Am I missing something here? I've got it set to the 317L Haywire and 24 gauge just like my GPlat, shooting for around .25 dual coil build on an ID of 2.4 mm. Tells me 10 wraps, I build, pinch, mould, and it comes out to .1 ohms. I don't expect this to be perfect, but why is my measurement so far off from my calculated?
Steam Engine and GPlat
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it doesnt help you to understand why its so far off your prediction but what i tend to do with new wire's or exotic/twisted wire's etc that i've built is run a length in an atty sat on a ohm reader and adjust the length till i get the ohm's i need, no need to make coils at this stage you are just trying to find the length>ohms ratio, i then measure the length including the wire that go's through the post holes
Did you torch the wire first? Without an oxide layer, the SS will just short itself out.
With your specs... I get 126.4mm wire length for a net resistance of 0.25Ω / 101mm for a net resistance of 0.20Ω... and 50.6mm for 0.1Ω net.
Twgbonehead may have something here, but would require a decent bit of research to validate or shoot down.
Kanthal A1 is comprised of iron, chromium and aluminum. When heated, an aluminum oxide layer, both thermally conductive and electrically resistive, is promoted to the wire surface. As long as a sufficient alumina (Al₂O₃) layer exists, surface electrical conductivity remains minimal.
Possible questions are...
What is the most likely, electrically resistive oxide layer produced by 317L, and at what temperature is it promoted to the surface... if any?
What determines the conversion from metal to metallic oxides... if it's temperature, does temperature alone promote oxides to the surface, or does the specific metallurgy play a roll?
The melting point of aluminum, at 1,221°F, is well within the functional parameters of Kanthal A1, which has a melt point of 2,732°F... while the basic melting points of the most likely oxide promoting metallic compounds found in 317L are:
nickel - 2,650°F
chromium - 3,465°F
molybdenum - 4,753°F.
chromium - 3,465°F
molybdenum - 4,753°F.
Interesting that the melting point of 317L is 2585+/-°F... well below the melt point of the above 317L individual metal components. Ignoring the specific temperatures for a moment, and taking into account other temperature "controls" like oxygen, lets run with a stand alone question...
Of the above metals, which is the most likely (if any) to provide a "Kanthal A1 like" high thermal conductance with low electrical conductivity, under the conditions found in an vaporizer/atomizer... and of those which is the most likely to occur?
As I have time - although I may be barking up the wrong tree - I'll research these questions. If anyone else would like to conduct a bit of research themselves... don't let me hold you back. ;-)
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No I did not torch it first, I never put much thought into that because of how malleable and easy it is to work with right off the hop. I will give this a shot and see if it helps, thank you.
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I was just going by experience with SS mesh. If you don't torch it, it will short out your coils. Torching it does change the color of the mesh, and allows you to wind coils around it without them shorting to the mesh.
And, the melting point of alloys isn't that strongly related to the melting points of the components. As an example, the melting point of (water + salt) is lower than the melting point of either one.
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