Yeah absolutely. My question would be did he check with anyone technical - perhaps not. But he still chose to answer using a technical term - coefficient. But it's very hard to know what that means, given the large language barrier. He probably just copied it out of my email because I said it. It probably doesn't tell us anything, but at least it wasn't a definite no.
I've not started using Ti yet but yeah I understand it's easy enough with an 80-90° offset. But 'easy enough' doesn't mean I wouldn't wish it to be perfect
Oh that's really interesting, I already have two rolls of SS317L wire. I bought them because people were talking about its benefits over Kanthal, but I've still not actually tried it. I didn't realise it might also work (somewhat) with TC. Well then I'll definitely be trying that on the new flask as well, then.
I just did some searching and the only clear figure I could find for Stainless Steel was for 304 grade, which is 0.00094. I don't know if 317L might differ and, if so, in which direction.
A figure of 0.00094 makes it 6.3 times lower than (pure) Nickel, suggesting that a Nickel Purity value around 14 might theoretically work - with the usual caveats/assumptions: that 100 = 0.006; that there's no other factors involved; and of course that Nickel Purity even does modify the expected coefficient.
But with these very low coefficients, I think the main question becomes can the chip and mod be granular and accurate enough in its resistance reading to be workable?
- A Nickel coil that starts at 0.1Ω and 20°C and then increases to 232°C (about 450°F) will increase in resistance to 0.2272Ω.
- That's an increase of 0.1272Ω from a 212° temperature rise.
- Which is 0.0006Ω per °C - (which is coefficient value / 10 for reasons I can't quite understand..)
- A SS coil that starts at 0.1Ω and 20°C and then increases to 232°C will jump in resistance to 0.119928Ω
- An increase of only 0.019928Ω
- Which is 0.000094 per °C (again, coefficient / 10)
- In the SS case, the difference between:
- 300°F and 450°F (83°C) is a difference in resistance of 0.0078Ω
- 400°F and 450°F (28°C) is a difference in resistance of 0.0026Ω
In other words, compared to Ni200 we need nearly a whole order of magnitude greater accuracy in reading resistance. With the original dna 40 and Ni200, we were talking about each 0.01 pushing the temp out by about 30°F. Now we're looking at 0.001 gradients pushing it out by 20°F.
It would be fantastic if it did it. And there's got to be a reason why they let the chip go down to 10 on that scale, and sell it as being for really low grade Nickel. But I'm guessing that really low grade Nickel probably still has a higher coefficient than SS? EDIT: SS317 is up to 15% Nickel. So surely 'low grade Nickel' probably means it's still at least 60 or 70%, else it wouldn't even be Nickel any more. So probably still a much higher coefficient than SS.
Anyway, none of this is meant to dispute your point which is that the Nickel Purity feature might help SS work better with TC - if it works like we hope, quite likely it will. My feeling is that it won't make it a viable alternative to Ni200 or Ti as a prime TC wire, but it might for example get it to the point where it at least doesn't burn cotton.
And who knows - perhaps they did make Nickel Purity work down to these sorts of levels of coefficient, and also made the resistance reading extremely accurate. We know the Yihi chips display resistance to 3 decimal places when Set Resistance is done, suggesting they might be using that granularity internally. Perhaps Infinite have done the same.
So with the right atty providing a perfect 510 connection, and optimum coils, maybe it could function on a par with the main two TC wires. Again, with the big caveat that this assumes that many assumptions are right
In addition to the general ones, also that the coefficient for the SS we'd use, 317L, is not even lower than the 0.00094 I found for SS304.Disclaimer: I kind of suck at maths so forgive me - and correct me - if there's any glaring errors in this. I also don't fully understand the coefficient calculation: the differences mentioned in my bullet points are calculated using a Coefficient of Resistance calculator, using starting resistance 0.1 and starting temp as 20°C, with ending temp as 232, 204, 149 - being 450, 400, 300°F respectively. But when I try to do 204°C to 232°C, using the starting resistance as the ending resistance from 20->204, I get a slightly higher end resistance than when I do 20->232 direct. I don't understand this, nor know if it matters - it might simply be that the calculator is truncating some decimal places on the resistance input and so rounding errors are introduced.
But the figures I have got seemed to be corroborated by my general understanding of TC, such as knowing that with Nickel 0.01Ω should be around 30°F of difference.
We must all buy all the boxes
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