Need some help converting to non regulated

[Cowboy192]

I need a bit of help figuring out where to start on a non regulated build,
I normally vape with a lemo built to 1ohm 8wraps 3.5mm id using 26awg nichrome 80 running 21w
But I'm ordering myself a bottom fed device as I fancy trying a squonker, not sure where to start build wise for a comparable vape on an unregulated build,
I have 26, 28 and 29awg kanthal to hand, prefer single coil builds and wick with rayon, what do you recommend?

 

[dbrandt01]

What bottomfed device?
I'm bias to Reo, but there are multiple devices for squonking.

As far as building and a lot of information, watch @super_X_drifter He has a ton of atty videos with building portions in them. sxmxdrifter - YouTube

He has a lot of information about bottomfed mods since it's all he uses. With 28g you could do 10 wraps around 2.4mm diameter and that should put you close to 1.0 ohms on single coil. I find my Reo shines at 0.5-0.7 ohms. Plus if you went 0.8 ohms let's say and fully charged battery that'd put you at 22w roughly so it could be close to the same experience.

 

[State O' Flux]

Remember that you're dealing with Ohm's law...
The calculated wattage doesn't care about your wire gauge or coils in parallel count... just the net resistance and battery voltage.

Heat flux does care about the wire gauge (AKA wire surface area & mass), coils in parallel count and net resistance, and is directly affected by them, both together and independently.
Heat flux is the coil(s) radiant heat, expressed in milliwatts per millimeter of coil surface area... squared. For our purposes... it's simply how warm you perceive your vape to be.
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Duplicating your current 1.0Ω, single coil Nichrome build with 26 gauge Kanthal A-1 will provide a heat flux that is similar - 140 mW/mm² for Nichrome at 21w vs. 159 mW/mm² for Kanthal at an Ohm's law calculated value of 18 watts at 4.2V... however, your surface area drops from 142.62 mm² (Ni) to 105.32 mm² (Ka).

So... temperature, easy - coil net surface area, not so much. At least, not with the wire gauges you have on hand.
More coil surface area = more juice can be vaporized, per firing.

As long as you run at 1.0Ω, the max discharge, with a unregulated mech, will remain at 18 watts. If you change wire gauge towards thinner, you increase heat flux and reduce surface area. Inversely, increasing thickness will decrease heat flux (which is not that warm to begin with below 200 mW/mm²) and increase surface area.

Lowering your resistance, for a given gauge will increase heat flux. Increasing wire thickness increases coil surface area... but at the loss of coil temperature, for a given wattage. So... lets see what can be tossed together, to get closer to your desired values.

A single 0.7Ω build will produce a discharge of 25 amps (at 4.2V)... with 24 gauge, which you don't have... the result will be a heat flux of 158 mW/mm² and a surface area of 148.9 mm².
This may be as close as you're going to get to your original values (without spending more time with additional fine tuning)... both slight increases over your original Nichrome values. Sorry we have to go with a gauge you don't have to accomplish it.

There may be alternatives that haven't been explored. I can only go with what I know (or think I know), and the amount of time I'm willing to spend on someone else's issues.

All calculations done with Steam Engine... 3.5mm base mandrel / 6mm net leg per coil.

 

[DaveSignal]

I need a bit of help figuring out where to start on a non regulated build,
I normally vape with a lemo built to 1ohm 8wraps 3.5mm id using 26awg nichrome 80 running 21w
But I'm ordering myself a bottom fed device as I fancy trying a squonker, not sure where to start build wise for a comparable vape on an unregulated build,
I have 26, 28 and 29awg kanthal to hand, prefer single coil builds and wick with rayon, what do you recommend?

Here is a short answer:
use the 26 gauge kanthal and wrap 6 wraps around a 2mm screwdriver, dual coils. Each wrap of 26 around 2mm is about .1 ohm, so .6 ohm per coil with dual coils equals a total build resistance of .3 ohm, give or take some hundreths. This is going to be a good vape and is safe a for standard high-drain 20A+ 18650 battery.

You could also do the same thing with 8 wraps per coil of 26 gauge nichrome.

 

[Cowboy192]

Ok I'll give it a try, I'm using Samsung 25r's just wanted a cool flavourful vape and didn't know what to do build wise

 

[Cowboy192]

What bottomfed device?
I'm bias to Reo, but there are multiple devices for squonking.

It's the 3fv clone of the reo, I want an original reo but never having tried unregulated mods I thought I'd try something more affordable to see if I like it or get the use out of it before I shell out a couple hundred dollars (but if I do like it I already have a reo grand and a woodvill on my want list)

 

[Cowboy192]

State that's the bit I was lost on, trying to get to the same sort of heat flux was boggling my head, I was getting tripped up On wattage from a full battery I think I have a good start point now!

 

[State O' Flux]

State that's the bit I was lost on, trying to get to the same sort of heat flux was boggling my head, I was getting tripped up On wattage from a full battery I think I have a good start point now!

If you remember that with a mech, Ohm's law provides your wattage value... and only a few things will change that value. If you toss out the 4.2V constant (I personally use 3.9/4.0v as constants), then really, all you have is net resistance as a controlling variable. No net actually, because you're using a single coil.

Once you insert your resistance and the resultant OL derived wattage... then you start to play with wire gauge. Balance surface area against temperature. If you can't get what you want, try a different resistance / wattage... and play with a new set of wire gauge factors to see how your priorities of surface area and temperature are effected.

I have a personal heat flux, that tends to adjust up or down depending on the atty used, but in broad strokes, around 220 to 320 mW/mm² is my current range... the low side for RTAs, the high side for RDAs.
You have a personal heat flux too... so try and keep that value in hand when working up builds.

When I start to work up a new build, I go from net resistance / wattage, to surface area / heat flux, to fine tuning of the previous factors if I have any excessive values in heat capacity or leg power loss. It's a progression of importance.