RDA Does my first RDA build look okay?

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Jumberlack

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i used premade twisted coils for it, but im not sure if it's normal. it's 0.18 ohms
build.jpg
 

sonicbomb

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By all means, in fact, try all the coils. Experiment and then experiment some more, find the coils you like through experience. I would suggest trying some plain round wire builds before branching out into anything more exotic to establish a base line of performance.

You may find this very useful as you can model builds and get an idea of their heatflux characteristics before you even cut a length of wire.
 
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jersey_emt

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Not bad at all for a first try. I also think you should go a bit lighter on the cotton. The density of the left coil on your second photo looks alright, but you only need the wick tails just long enough to touch the bottom of the juice well, not completely cover it. You definitely want the space underneath the coils to be clear to ensure proper airflow / cooling.

More wraps with twisted 26 or 28 gauge wire will probably work better for you too. The coils will heat up faster and there will be a lot more surface area touching the wick. Eight wraps or thereabouts is the sweet spot for me for basic twisted builds, but of course your preference will vary.
 

Jumberlack

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Not bad at all for a first try. I also think you should go a bit lighter on the cotton. The density of the left coil on your second photo looks alright, but you only need the wick tails just long enough to touch the bottom of the juice well, not completely cover it. You definitely want the space underneath the coils to be clear to ensure proper airflow / cooling.

More wraps with twisted 26 or 28 gauge wire will probably work better for you too. The coils will heat up faster and there will be a lot more surface area touching the wick. Eight wraps or thereabouts is the sweet spot for me for basic twisted builds, but of course your preference will vary.

thanks. do you have an idea of how many wraps of 28g twisted wire to get about a .3 ohm dual coil build?
 

sonicbomb

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jersey_emt

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thanks. do you have an idea of how many wraps of 28g twisted wire to get about a .3 ohm dual coil build?

Don't worry about the resistance. You're using a regulated mod, so you don't have to build super low resistance coils to get a good vape. In fact, building to a higher resistance will give you better results with a regulated mod, since you will have more wraps (more surface area) and can just turn up the wattage to account for the extra wire mass.

0.3 ohms for a dual coil twisted 28 gauge build is rather low. You're only going to get 4 or 5 wraps, and it will be a rather hot vape. Eight or nine wraps with a 3 mm diameter will be around 0.5 - 0.6 ohms, which is a good starting point for twisted 28 gauge builds.

that's a bit too complicated for me with twisted wire, im not sure the twist pitch ect

Twist pitch is just how tightly twisted your wires are -- the distance from one 'x' to the next 'x' in the wire. Your 24 gauge build is very loosely twisted, I'd say about 2.25 - 2.5 mm. I'd recommend a tighter twist next time, it will have more little nooks and crannies for the juice to flow onto the coil from the wick. Twist the wire until it breaks off on one end, and the twist pitch will be around 0.75 - 1.5 mm depending on wire gauge (28 gauge will be closer to 0.75 mm, 24 gauge will be closer to 1.5 mm). If you're not sure, just enter in 1 mm for the twist pitch for tightly twisted wire and it will be close enough. The twist pitch doesn't change the results all that much.

So tightly twisted 28 gauge wire, 3 mm diameter, 1 mm twist pitch, dual coil: 8 wraps will be about 0.53 ohm, 9 wraps about 0.60 ohm. Either build if wicked properly will easily handle 100 watts without being extremely hot, but I usually run those builds at 60 - 70 watts.
 
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Jumberlack

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Don't worry about the resistance. You're using a regulated mod, so you don't have to build super low resistance coils to get a good vape. In fact, building to a higher resistance will give you better results with a regulated mod, since you will have more wraps (more surface area) and can just turn up the wattage to account for the extra wire mass.

0.3 ohms for a dual coil twisted 28 gauge build is rather low. You're only going to get 4 or 5 wraps, and it will be a rather hot vape. Eight or nine wraps with a 3 mm diameter will be around 0.5 - 0.6 ohms, which is a good starting point for twisted 28 gauge builds.



Twist pitch is just how tightly twisted your wires are -- the distance from one 'x' to the next 'x' in the wire. Your 24 gauge build is very loosely twisted, I'd say about 2.25 - 2.5 mm. I'd recommend a tighter twist next time, it will have more little nooks and crannies for the juice to flow onto the coil from the wick. Twist the wire until it breaks off on one end, and the twist pitch will be around 0.75 - 1.5 mm depending on wire gauge (28 gauge will be closer to 0.75 mm, 24 gauge will be closer to 1.5 mm). If you're not sure, just enter in 1 mm for the twist pitch for tightly twisted wire and it will be close enough. The twist pitch doesn't change the results all that much.

So tightly twisted 28 gauge wire, 3 mm diameter, 1 mm twist pitch, dual coil: 8 wraps will be about 0.53 ohm, 9 wraps about 0.60 ohm. Either build if wicked properly will easily handle 100 watts without being extremely hot, but I usually run those builds at 60 - 70 watts.

that's strange, i just made a 28g 6 wrap twisted coil and it's reading .87 ohms. what could i have done wrong?

edit: after messing around with it and adding a second coil it's now at .37 ohms which isn't as far off
 
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jersey_emt

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that's strange, i just made a 28g 6 wrap twisted coil and it's reading .87 ohms. what could i have done wrong?

edit: after messing around with it and adding a second coil it's now at .37 ohms which isn't as far off

0.37 ohms is pretty far off for a 6-wrap twisted 28 gauge dual coil build. To get that low with twisted 28 gauge wire it would only be 3 wraps. You might have a short. Or might your 28 gauge wire be stainless steel and not Kanthal? Stainless steel wire has about half the resistance of Kanthal wire.

Can you post a photo of your build? What diameter are your coils? I'm assuming 2.5 mm - 3 mm.

And why only 6 wraps? Eight or nine is where you should be starting out for a twisted 28 gauge build.
 

Jumberlack

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0.37 ohms is pretty far off for a 6-wrap twisted 28 gauge dual coil build. To get that low with twisted 28 gauge wire it would only be 3 wraps. You might have a short. Or might your 28 gauge wire be stainless steel and not Kanthal? Stainless steel wire has about half the resistance of Kanthal wire.

Can you post a photo of your build? What diameter are your coils? I'm assuming 2.5 mm - 3 mm.

And why only 6 wraps? Eight or nine is where you should be starting out for a twisted 28 gauge build.


i already took that one apart, but right now i'm working on a twisted 24g 8 wrap dual coil. i'll post a picture in a few minutes when i'm done...im aiming for .3 ohms
 
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