Is Kanthal Unstable?

[tim]

I'm not sure I actually mean unstable, more a manufacturing issue. I'll explain

I can make a coil from Ni200, Ti, SS, etc exactly to the result Steam-engine says it will be. Even dual coils are accurate (maybe 0.01 out). However, when I use Kanthal, which I use for work, a coil can be as much as 0.6 wrong on a dual coil set-up. I'm not particularly bothered by it, but wonder if Kanthal is an imperfect wire.

[b1mble]

It isn't,

If it is actually made to the specs the patent owners have.

Which all of it made in China probably isn't.

[SteveF]

its all down to purity, ni200 and titanium G1 are 99.**‰ pure
SS grades can be fairly close to the ideal alloy specs but kanthal comes in A, B, C, D/E grades and all plus or minus 2-3%.
Same with nichrome 40,50,60,80% nickel

I found not all wires sold as Kanthal-A or nichrome 80 are what they should be, I bought some Chinese nichrome claptrap wire, sold as N80 the resistance was indicative of maybe N60. Proper claptrap.

Come to think of it neither is some titanium, it's probably not uncommon to get grade 2 ti alloy in stock coils.

[SteveF]

actually that's a long way out, 0.6 on dual coils would be 1.2ohms on a single.
what diameter wire are you making coils with?

[tim]

Sept 5, 2016 2:08:23 GMT SteveF said:

actually that's a long way out, 0.6 on dual coils would be 1.2ohms on a single.
what diameter wire are you making coils with?

Yeah, sorry, 0.6 was single coil difference, but only in the worst instance. I'm not that worried about it, as it hardly makes much difference at all. I just wondered why I only get that anomaly with Kanthal.

[djs]

Sept 9, 2016 21:39:07 GMT tim said:

Sept 5, 2016 2:08:23 GMT SteveF said:

actually that's a long way out, 0.6 on dual coils would be 1.2ohms on a single.
what diameter wire are you making coils with?

Yeah, sorry, 0.6 was single coil difference, but only in the worst instance. I'm not that worried about it, as it hardly makes much difference at all. I just wondered why I only get that anomaly with Kanthal.

Maybe you got some Friday Kanthal.... made by a crazy-arsed machine that is on the blink.

I know what you mean though....

[tim]

Sept 9, 2016 22:09:22 GMT djs said:

Sept 9, 2016 21:39:07 GMT tim said:

Yeah, sorry, 0.6 was single coil difference, but only in the worst instance. I'm not that worried about it, as it hardly makes much difference at all. I just wondered why I only get that anomaly with Kanthal.

Maybe you got some Friday Kanthal.... made by a crazy-arsed machine that is on the blink.

I know what you mean though....

Well, it did come from The Crazy Wire Company......

[ukwarrior]

As mentioned there are different grades of Kanthal, and also if bought from China I doubt it would be the same alloy as Kanthal bought here in the UK.

However, 0.6 is a big difference! I did read a few days ago on another forum someone having issues with their builds being higher resistance than they should of been- it turned out their '22 gauge' kanthal was actually mislabeled 26G kanthal.

I would stick to good suppliers if you can, to get a consistent wire type. I find this especially important in the case of other wire, like SS316L, where a different alloy could throw off TC on my devices.

[monty]

Just guessing, perhaps the rogue wire isn't uniform thickness.