TCR - is there too much guesswork?

[allen]

okay.....

I've been trying to set a manual value for 316L on my joyetech mods (rx200, mini and cuboid) so I can tweak it a little bit. I understand every batch of wire could be a little different to the next and so, sometimes, a tweak could be good.

I've been having major headaches with the manual TCR input and so I contacted Stealthvape and got a really detailed repy back (top work there SV!). seems the correct TCR for 316L is 88, I've trawled reddit and other forums and it looks like a lot of people suggest the range 88-92 on min / cuboid / rx200. I tried it. naaah. that setting sucks
even on this thread https://www.planetofthevapes.co.uk/...d-vaping/threads/coiling-with-ss.97408/page-3 people have suggested settings of 108 and 200
it seems to me it's just total guesswork folks? the TCR for 316L is somewhere in the range of 88 to 200 then?
not a dig at all at anyone but a genuinely confused question.

the odd thing is if I use the same attie on the preset programmed SS values (which could be for 316, could be 316L depending on where you read), I get a decent vape at 420F and only 15 watts (this is with a spaced single SS coil at .81ohms)
if I then go back to manual input and set the recommended 88-92, there's virtually no vapour. none. to get such bad results on the pre-programmed bit I Have to dial down to 290F (I hope that comparison makes sense?

so, what worries me is this:
we're buggering around bumping TCR settings up and down however we like in order to get a nice vape -
Surely, that value is there to limit temperature but adjusting it just bypasses the limiters.
We set a tempertaure at, for example, 480F with what is basically a guessed TCR and hit that fire button...... at that point does anyone really know what temperature their coil is reaching. is it 480? 320? 700?

I've seen threads elsewhere of people 'tweaking' the TCR for titanium too
and if titanium gives off really bad shit at over 600F...... is that coil going to be over 600F ???? damned if I know.

bottom line for me, is I think this little eureka moment has completely turned me off titanium - my impression is it's all very hit and miss with a whole new set of potential health risks. I'm not sure I trust this new technology yet with something as volatile as titanium

what's your thoughts / suggestions please?
Am I totally deluded? okay yes I am but that's another story

 

[tootingyoda]

I've basically given up with tcr settings on my cuboid and koopor mini, and only use the default ss setting. I adjust both the wattage and temp until I'm happy with the vape with minimal fuss. I only use ss as all these other exotic metals scare me if I'm honest, plus ss can be used in wattage mode if required.

Or maybe I'm just lazy....

 

[Tubbyengineer]

Most of the problem is that there are so many versions of SS and so many unscrupulous sellers claiming their wire is such and such a grade when really it's any old SS they can get their hands on that there are literally dozens of varying suggestions for the TCR value. The only way to be sure that you've got the right on is to buy from a reputable vendor and ensure you get the TCR value from them.
The correct generic setting for SS316 is the 880 recommended on Steam engine, 879 for 316L.

Another point to remember is that if your build is bad then all the TCR tweaks in the world won't fix it.

 

[allen]

Most of the problem is that there are so many versions of SS and so many unscrupulous sellers claiming their wire is such and such a grade when really it's any old SS they can get their hands on that there are literally dozens of varying suggestions for the TCR value. The only way to be sure that you've got the right on is to buy from a reputable vendor and ensure you get the TCR value from them.
The correct generic setting for SS316 is the 880 recommended on Steam engine, 879 for 316L.

Another point to remember is that if your build is bad then all the TCR tweaks in the world won't fix it.

Fair point. Mine was bought from stealthvape and so should be very good
It works consistently (and pretty well) on the preset and so shouldn't be too bad a build.
Ive played with the manual setting (while leaving temp and wattage the same) and it performs about the same when i set the tcr to 130

Does that mean the preset value is 130??
What's other people's experience please?

 

[Mr Numpty]

I wonder if part of the problem is due to ss being poorly suited to TC. NiFe30 and Ti work brilliantly on the vtc mini in both preset and TCR settings. With ss316 I do get a decent vape on the preset but the mod is clearly having to work hard to achieve it and I find I have to experiment to find the small window of wattage and temperature where it works without too much pulse modulation.

 

[tootingyoda]

Weird thing is my koopor mini is set to 40w, 180c, standard ss, on a dual ss coils at 0.24ohms on my goblin mini v2, but it rarely gets to 180 and runs around 29w and 170c max, no matter how much I crank it up. Vape is warmish, and flavour is good so I'm happy for now. Yet to really play with it on my cuboid, which is currently keeping my Griffin going, also with ss on tc mode.

Much more playing is in order methinks.

 

[danb]

so, what worries me is this:
we're buggering around bumping TCR settings up and down however we like in order to get a nice vape -
Surely, that value is there to limit temperature but adjusting it just bypasses the limiters.

The issue you describe is a symptom of the 3234123123 types of SS on the market and the high relative difference in their TCRs. With SS there will always be quite a lot of trial and error involved. Because the TCR of SS is so low, a small absolute change in TCR is a high relative change and translates to a large difference. Other wire types are more consistent because there are fewer types available and small absolute variations in a higher TCR are also relatively small, meaning there isn't really any need to tweak TCRs for them.

For example, setting TCR to 100 for a wire with an actual TCR of 90 will mean you have an 11% error (about 25C off). Setting TCR to 360 for a wire with an actual TCR of 350 would only be a 3% error (<10C off) - so even if the actual TCR of Ti varies a bit between manufacturers, it doesn't make much difference in practice. For low TCR wires, seemingly small variations make much bigger differences and you have to fiddle with your TCR settings.

Temp sensing accuracy aside, this is another reason I haven't bothered trying SS.

 

[Tubbyengineer]

The issue you describe is a symptom of the 3234123123 types of SS on the market and the high relative difference in their TCRs. With SS there will always be quite a lot of trial and error involved. Because the TCR of SS is so low, a small absolute change in TCR is a high relative change and translates to a large difference. Other wire types are more consistent because there are fewer types available and small absolute variations in a higher TCR are also relatively small, meaning there isn't really any need to tweak TCRs for them.

For example, setting TCR to 100 for a wire with an actual TCR of 90 will mean you have an 11% error (about 25C off). Setting TCR to 360 for a wire with an actual TCR of 350 would only be a 3% error (<10C off) - so even if the actual TCR of Ti varies a bit between manufacturers, it doesn't make much difference in practice. For low TCR wires, seemingly small variations make much bigger differences and you have to fiddle with your TCR settings.

Temp sensing accuracy aside, this is another reason I haven't bothered trying SS.

See science does come in handy...
Joking aside I've picked up a roll of SS from Stealthvape to give it a try, I'm not hopeful for the TC results - as you say there just Isn't enough overall resistance change in a coil to make it truly accurate, or even reasonably accurate, but I'm sure it will serve me well as a "Standard" resistance wire...

 

[danb]

I'm sure it will serve me well as a "Standard" resistance wire...

I'd interested to see the graphs (compared to NiFe30 for example) when you have them.

 

[steves]

Fair point. Mine was bought from stealthvape and so should be very good
It works consistently (and pretty well) on the preset and so shouldn't be too bad a build.
Ive played with the manual setting (while leaving temp and wattage the same) and it performs about the same when i set the tcr to 130

Does that mean the preset value is 130??
What's other people's experience please?

As far as I know, most of the SS presets at the moment are set for SS 304 unless otherwise stated. I know a lot of people who are having issues with 316/316L/317 and its not clear to me why but as @Tubbyengineer said, the build quality is crucial with these low
TCR wires...I just stick to NiFe48 these days. NiFe is so much easier..lol!