Strap in kiddies, this could be a long one. 
This forum and others have a ton of information out there on the DNA40. There's a plethora of information, some good, some bad. There isn't one single source that seems to have it all bunched together, at least that I've found. So that's what I'm going to attempt to do. Pull all the good information I know as well as everything that I've personally found to work best for me. This isn't a "right or wrong". If you do things differently than what I lay out here that doesn't mean it's wrong, it just means that I personally have found it to work better a different way. Your results may vary.
One of the hardest things I think about the DNA40 device is that it works. It doesn't really matter what you do. From building a coil way out of spec, having a coil that fires ridiculously unbalanced or badly, to having poor wicking. Whatever you do it still works. That's a great thing, but in the same respect I feel like it can be bad, because it means that someone may not be getting near the quality vape they should be and may not even realize they have a problem.
Anyway, there's a lot of confusion out there on these things, and I hope to clear some of this up. So what gives me the right? Nothing. I don't work for Evolv, I'm not an expert on the DNA40. I am a very experienced vaper and have owned the DNA40 long enough that I've done a lot of experimentation with it. I've tried just about every possible variation of things out there to see what works best, at least for me. So my hope for this thread is to maybe answer some questions, pull a lot of information into one resource, and above all, for someone brand new to the DNA40 device who may not know where to even begin, hopefully this will be a guide that can be followed to give them a good quality vape that they can later improve on however they like.
So without further intro, let's jump right in.
Issues:
I first want to cover some of the issues I've encountered around the net as well as through personal experience.
1) Some early boards were released that had exposed vias under the ribbon cable for the screen. The errata in the user manual mentions this. This results in a screen garbling issue as well as some other strange effects including it resetting the base resistance of the atomizer once it idled off. Evolv then started releasing these boards with some "gray goop" under the ribbon cable. In some cases I'm sure this resolved the problem, however not in all. I personally owned one of these boards that had been factory fixed, yet it still exhibited the issues. The second board I had had no gray goop, but the conformal coating on the PCB was fixed and this board has functioned flawless in every way for me.
2) "It doesn't always detect a new coil". It's not supposed to. It tries to be "smart" about coils and if it's pretty sure it's not a new coil or the coil is the same resistance as the previous coil then it won't ask. I don't know the exact processes here, but the bottom line is, it won't always ask.
3) "It drops in and out of TP mode", or "My coil keeps changing resistance." This is almost certainly a result of a loose connection on the coil. Because nickel wire is so much softer than kanthal it's common for posts to not be tightened as much as normal (when using through-hole posts). Constant heating and cooling causes contraction and expansion which can loosen up screws and connections pretty quickly. So a common question is why this wasn't such a big problem with kanthal. First as pointed out nickel is much softer. Second, a few hundredths of an ohm difference on a kanthal coil isn't going to make much difference. You're hitting it with a fixed voltage so that change won't really change the wattage nor the output much. However on the DNA40 since the resistances it measures in TP mode are so small to begin with, it's MUCH more sensitive to this. Coupled with the fact that it uses that resistance to determine how much voltage to output. In short it means that kanthal is VERY forgiving when it comes to loose terminations. Nickel on the other hand, with the DNA40 is NOT. You must have absolutely positive terminations for your coils. Using the tops of the screw posts instead of through holes is one method. Work hardening the nickel is another. I have had good success with both work hardening the nickel as well as doubling the legs that go through holes. Until we can get atty's that are better designed for nickel this is the best we can do.
4) "This morning it was vaping like a champ, now I pick it up and I'm get a much weaker vape." This generally is caused by the same as above. A loosened connection. Think of it this way (I'm using arbitrary numbers). Let's say you have a coil that's .11 ohm. And at your maximum temperature limit setting of 450 degrees it reaches .17 ohm. So now one of your coil connections gets just a little bit loose. So what was reading at .11 ohm at room temperature is now reading at .14 ohm at room temperature. So now the DNA40 thinks the coil is sitting at 250+ degrees even though it's room temperature. What happens when you vape? It let's the temp of the coil only raise 200 degrees... So you're getting less than 300 degrees on the coils now before temp limit kicks in. This is again why positive terminations are an absolute must. It doesn't take much at all for a few hundredths of an ohm change in resistance, but that can have a big impact on the temperature the coils are allowed to reach. If this happens your best bet is to tighten down the connections, let the atty cool to room temp, and try again. If it asks if it's a new coil just tell it yes (as long as it's at room temp)
Wire:
So now you're going to need some coils. But before you can do that you're going to need to prepare your wire. NI200 is very soft. So especially if you're using a higher gauge wire you're going to need to work harden it. This will make it easier to work with and less likely to get cut off in post holes if you use them. I used to use a method that was essentially cold rolling it. Hold one end and then with the other hand covered in a tissue or cloth to make it slip easier pull your hand down while using your fingers to bend a "Z" shape in the wire. Repeating this 20+ times. Each time the wire gets a slight bit harder then the time before. However, recently I tried the drill method. This works just as well and is much easier and faster. Rip Trippers has a video titled "Straightening Kanthal" where he demonstrates this method. If you aren't hardening the nickel like this, you truly have no idea what you're missing and how much frustration you can save yourself. Once the wire is hardened it doesn't hurt to give it a good cleaning. I use some electronics grade alcohol that's 99.9%. You can use dish soap or any other method. You just want to get the wire as clean as possible to make sure there aren't any remaining residue from manufacturing. If you choose to glow your coils (which I do) then this step is more optional since any residue should burn off anyway. I still clean it regardless though.
Coils:
So your wire is ready and now you need to wrap your coil(s). Have you decided what type of build you are doing? When doing nickel builds we have to remember that the DNA40 is most effective in the .1 to 1 ohm range. It will fire below .1 but it won't be able to do so at maximum power as the current is limited. So try to stay in that range. The next step is to try to determine how you can achieve the maximum surface area for your build while still maintaining a good heat flux. If that sounds a bit complicated, it's really not. Remember our temperature is going to be limited. So the more surface area we can spread that temperature over, the more power we can put into our coils. The more power the more vapor. Now that's assuming we want the maximum power. If we don't then we just build for whatever surface area we want and verify that the approximate wattage we want to run is going to perform well for it.
So if I'm building for a kayfun that I know I'm probably going to be running about 15W. Using Steam Engine for the build I can see that if I use 28awg on a 2.5mm mandrel and do 10 wraps I can hit .13 ohm with a single coil. Steam Engine tells us two very important things. First it tells us that at 15W our heat flux is going to be 141mW/mm^2. If that number is meaningless to you, just look at the little fire symbol beside it... It scales from blue to red... You want to try to stick around the green to greenish yellow for the power you want to run. The other thing it tells us is heat capacity. I won't go into a full out discussion on this, but in general the lower the heat capacity the better. It will have less "lag time" (which isn't a problem for the DNA40, especially when running builds that won't hit high wattage anyway), but it will also stay hot longer after firing. Again not a big deal but just try to keep it low if possible. Less metal in the coil means less heat capacity, but remember you don't want to sacrifice surface area to do it. So in this case 34mJ K-1 is a little high especially with the limited airflow in a kayfun, and we may want to consider dropping down to 30awg instead, but for now we'll just let it ride.
Now suppose we were building for a dual coil RDA. And we want to get as close to maximum out of this thing as possible. We want it to utilize about as much of the 40 watts as possible while getting as much surface area as we can. So we head back to Steam Engine and play around with the numbers. Now in this case since we have a lot more room in our RDA we decided to go with a 3mm inner diameter. Using 30awg wire we can see that using 11 wraps for each coil will give us a .12 to .13 ohm coil. At 40W that's going to give us a heat flux of 196mW/mm^2. That's pretty warm, but remember we want the maximum we can get out of this thing. That's going to be about perfect. That means during a draw it probably won't drop more than a few watts to maintain our temperature with a strong draw on the RDA. If we found that it was dropping more than a few watts then we can add another wrap or two to the coils to lower our heat flux. For now this should be pretty close to perfect.
Now before we move on, I've given you two different examples here. That's exactly what they are, examples. You don't have to build these builds or match them. You don't have to use a certain number of wraps or a certain gauge of wire. What I'm demonstrating here is how to "Read the numbers" to figure out what you want to build. If you're building in an Orchid you know you can't use a giant inner diameter, if you're building in a kayfun you can't have 20 wraps. Etc... You can also use it to get an idea of what power levels that build can handle and approximately where it's going to be running (with optimum wicking) based on the heat flux. In the first example we were just building for lower wattage to get a decent vape from our kayfun. In the second example we're building a coil that can take full advantage of all the 40W the DNA40 has to offer to generate large flavorful clouds and still fit in in a smaller RDA.
Building:
Ok, so now you know what coil you want to make and your wire is ready. Time to wrap your coils. No different than building for kanthal. The one exception is when mounting. Again as covered under the issues section, even after hardening it's still fairly soft. If you are using through-hole posts for your legs, make sure the screws in the posts don't have burred edges at the bottoms. A lot of times a couple of passes on some sand paper can turn what used to be a pair of scissors into a great wire gripping machine. Also if you are having difficulty with legs getting "cut" doubling the wire on the coil leg can help. On some RDAs I've found that the center post is fine since it has two legs passing through it, but the ends want to cut. So double the end legs and let the center ones alone. Just make sure you can get them good and snug without cutting them in two. Remember you want these connections to be as tight as possible to prevent fluctuations in resistance. Even very small changes in resistance will through the TP mode off so this is absolutely critical. Spend the time to get this right and it will be greatly rewarded and save lots of frustration later.
Once your coils are in there and in place you want to be sure they are firing evenly. If you're doing a spaced coil (i.e. spacing between the wraps) they are very forgiving and require pretty much nothing more before wicking. If you're doing a micro coil (i.e. contact coil) then you need to make sure it's firing evenly. To do that you're going to want to dry burn the coil and glow it slightly. You don't want to overheat the nickel. If it gets too hot it will get a little funky (noticeable by black "globs" that form on the surface most likely carbon deposits). Turn the TP off but drop wattage down way below what you expect the build to handle. In our 15 watt kayfun build I might use 5-6 watts... for our 40W RDA build I might use 20-25W. With power reduced and TP turned off, begin pulsing the coils. As they heat up you'll see them begin to darken. Watch carrefully for any hot spots. Almost every coil I've made will have one or two wraps that fire and glow while the others don't. Keep pulsing and allow the heat to spread across the coil while keeping the glow to a minimum. Then use some pliers or tweezers to squeeze the coils (NOT while glowing). You can use ceramic tweezers to squeeze while glowing, and with kanthal builds this works WONDERFULLY... With nickel I've found it to usually cause more harm than good. Instead pulse, glow, squeeze. Wash rinse and repeat. If you have dual coils and one coil is firing before the other squeeze the one that glows first. Keep going... Eventually you'll get the coils firing evenly from the center out (on both coils at the same time if duals). Now that it's even you can turn TP back on.
Now go ahead and wick your coil. Wick it the same as you normally work a kanthal build. Once exception is when using rayon. Because the nickel is much softer it's harder to pull a lot of rayon through a coil without deforming it. If you use rayon you know that you've got to have it packed pretty tightly in the coil itself. A trick I've seen and used that works great is to divide the amount of rayon down into half, then start from both sides of the coil pulling each piece in opposite directions. This distributes the force and pulls the coil together instead of in opposite directions.
Using TP mode:
So how does TP mode work anyway? Let's talk about exactly what the DNA40 does when you fire it. When you first press the fire button the DNA40 applies wattage to the coil(s). If the coils are below a certain temperature it will put higher wattage on them, even if you have a lower wattage set. For example, if the wattage is set at 15W then it might applied 30W for just a very brief fraction of a second. It wants to raise the temperature of the coils as fast as possible. Now once the temperature is raised it will now apply whatever wattage you have set. So in this case, 15W. It will continue to do that while monitoring the temperature of the coil. If the coil exceeds the temperature you've set as your limit, then it will reduce wattage to maintain that temperature.
So if our temp is set for 450 degrees and you are firing the device while drawing the temp may only reach 380 degrees so it simply keeps the 15W applied. Now towards the middle of your draw you start easing up and not drawing as hard. Less airflow means heat builds up faster. So now the temp reaches 450 degrees at which point the DNA40 begins reducing wattage to maintain 450 degrees. When you stop drawing entirely it might only be outputting 2W. That's ok, if you start drawing hard again it will output the full 15W you have set assuming that doesn't exceed the 450 degree limit.
There is a "temperature protected" message that can flash on the screen. Through experimentation what I've found is that this only displays when there is a large differential between the set wattage and wattage TP outputs. In other words, in our RDA build that can handle all 40W pretty well. Even though through most of a hard draw it may be constantly regulating the wattage down to 35-36-37-37-39 watts to maintain the set temperature limit, it won't give you the TP message. On the other hand, if we took our kayfun build and run it will set at 40W, it's going to regulate down to 12-13-14-15 to maintain the temp limit. That's way below the 40W we have set. So now the temperature protected message is going to flash. What that means is, you don't have to be "afraid" of the TP message. It doesn't mean anything bad other than it's just doing what it's designed to do. However it can be useful. For example in our RDA build which can handle the full 40W under normal circumstances, if we start seeing the TP message flash we know that it's now regulating the wattage down below what it normal does. Which means chances are our wicks are getting dried out and it's time to redrip (unless we're purposefully trying to dry them out to switch flavors.) If you want to set the unit at 40W and leave it there you can certainly do that. Even if the unit has to regulate down to 15W to maintain your temp limit it won't make any difference. Other than the flashing TP message might get annoying. If you want to get the maximum out of your particular build you can watch (....-eyed through a mirror) about what wattage it is utilizing to keep to your temperature limit and then set around or just barely above that setting. This will ensure you're putting in the maximum power your build will sustain while preventing the TP message from flashing every time you take a hit.
One last note about TP. The DNA40 can only regulate wattage down to 1W. If you were to make a very small or very poor build, or if for example you were trying to completely dry your wicks) if the unit applies 1W and your temp limit is exceeded it will kill power to the coil until it cools slightly, then cycle back on at 1W till it's hit again. This results in a pulsing or cycling of the coil/vapor.
So what's the best way to determine where to set the temperature limit? What I do is first determine the point where my wicking material will first start to burn. So I wrap a coil and place a piece of wick in it. Set the temp to say 450 degrees and fire for 4 or 5 seconds. Then slide the wick and check it. If there isn't any browning then I know that's fine so I can bump the temp up higher. Keep repeating this until you see the wick start to brown. Once you do then you know that's the point where you're going to start to burn the wick and you should use that as an "upper limit" for your settings. So let's say you're using cotton and you find your particular cotton can handle 470 degrees before it browns. So you know you never want to go above that setting. Now as for going lower, you'll find that as you lower the temp the vape will get cooler and the taste will change a bit. I personally find that 450 - 460 is right around the sweet spot. That's way below the char point of my rayon wick, but seems to give excellent flavor from just about every juice I own. I have found a couple of juices though that seem to give a slightly better flavor down as low as 410 -420, though those seem to be the rare exception. I suspect if you typically use juices higher in PG you might find they work better with slightly lower temps while higher VG requires higher temps.
That covers the basics. I hope this has been at least somewhat helpful. Again this isn't an absolute "this is what you should do", it's simply what I personally have found to work the best. I'll come back and add more and maybe some pics or something later... For now I've wrote enough!
This forum and others have a ton of information out there on the DNA40. There's a plethora of information, some good, some bad. There isn't one single source that seems to have it all bunched together, at least that I've found. So that's what I'm going to attempt to do. Pull all the good information I know as well as everything that I've personally found to work best for me. This isn't a "right or wrong". If you do things differently than what I lay out here that doesn't mean it's wrong, it just means that I personally have found it to work better a different way. Your results may vary.
One of the hardest things I think about the DNA40 device is that it works. It doesn't really matter what you do. From building a coil way out of spec, having a coil that fires ridiculously unbalanced or badly, to having poor wicking. Whatever you do it still works. That's a great thing, but in the same respect I feel like it can be bad, because it means that someone may not be getting near the quality vape they should be and may not even realize they have a problem.
Anyway, there's a lot of confusion out there on these things, and I hope to clear some of this up. So what gives me the right? Nothing. I don't work for Evolv, I'm not an expert on the DNA40. I am a very experienced vaper and have owned the DNA40 long enough that I've done a lot of experimentation with it. I've tried just about every possible variation of things out there to see what works best, at least for me. So my hope for this thread is to maybe answer some questions, pull a lot of information into one resource, and above all, for someone brand new to the DNA40 device who may not know where to even begin, hopefully this will be a guide that can be followed to give them a good quality vape that they can later improve on however they like.
So without further intro, let's jump right in.
Issues:
I first want to cover some of the issues I've encountered around the net as well as through personal experience.
1) Some early boards were released that had exposed vias under the ribbon cable for the screen. The errata in the user manual mentions this. This results in a screen garbling issue as well as some other strange effects including it resetting the base resistance of the atomizer once it idled off. Evolv then started releasing these boards with some "gray goop" under the ribbon cable. In some cases I'm sure this resolved the problem, however not in all. I personally owned one of these boards that had been factory fixed, yet it still exhibited the issues. The second board I had had no gray goop, but the conformal coating on the PCB was fixed and this board has functioned flawless in every way for me.
2) "It doesn't always detect a new coil". It's not supposed to. It tries to be "smart" about coils and if it's pretty sure it's not a new coil or the coil is the same resistance as the previous coil then it won't ask. I don't know the exact processes here, but the bottom line is, it won't always ask.
3) "It drops in and out of TP mode", or "My coil keeps changing resistance." This is almost certainly a result of a loose connection on the coil. Because nickel wire is so much softer than kanthal it's common for posts to not be tightened as much as normal (when using through-hole posts). Constant heating and cooling causes contraction and expansion which can loosen up screws and connections pretty quickly. So a common question is why this wasn't such a big problem with kanthal. First as pointed out nickel is much softer. Second, a few hundredths of an ohm difference on a kanthal coil isn't going to make much difference. You're hitting it with a fixed voltage so that change won't really change the wattage nor the output much. However on the DNA40 since the resistances it measures in TP mode are so small to begin with, it's MUCH more sensitive to this. Coupled with the fact that it uses that resistance to determine how much voltage to output. In short it means that kanthal is VERY forgiving when it comes to loose terminations. Nickel on the other hand, with the DNA40 is NOT. You must have absolutely positive terminations for your coils. Using the tops of the screw posts instead of through holes is one method. Work hardening the nickel is another. I have had good success with both work hardening the nickel as well as doubling the legs that go through holes. Until we can get atty's that are better designed for nickel this is the best we can do.
4) "This morning it was vaping like a champ, now I pick it up and I'm get a much weaker vape." This generally is caused by the same as above. A loosened connection. Think of it this way (I'm using arbitrary numbers). Let's say you have a coil that's .11 ohm. And at your maximum temperature limit setting of 450 degrees it reaches .17 ohm. So now one of your coil connections gets just a little bit loose. So what was reading at .11 ohm at room temperature is now reading at .14 ohm at room temperature. So now the DNA40 thinks the coil is sitting at 250+ degrees even though it's room temperature. What happens when you vape? It let's the temp of the coil only raise 200 degrees... So you're getting less than 300 degrees on the coils now before temp limit kicks in. This is again why positive terminations are an absolute must. It doesn't take much at all for a few hundredths of an ohm change in resistance, but that can have a big impact on the temperature the coils are allowed to reach. If this happens your best bet is to tighten down the connections, let the atty cool to room temp, and try again. If it asks if it's a new coil just tell it yes (as long as it's at room temp)
Wire:
So now you're going to need some coils. But before you can do that you're going to need to prepare your wire. NI200 is very soft. So especially if you're using a higher gauge wire you're going to need to work harden it. This will make it easier to work with and less likely to get cut off in post holes if you use them. I used to use a method that was essentially cold rolling it. Hold one end and then with the other hand covered in a tissue or cloth to make it slip easier pull your hand down while using your fingers to bend a "Z" shape in the wire. Repeating this 20+ times. Each time the wire gets a slight bit harder then the time before. However, recently I tried the drill method. This works just as well and is much easier and faster. Rip Trippers has a video titled "Straightening Kanthal" where he demonstrates this method. If you aren't hardening the nickel like this, you truly have no idea what you're missing and how much frustration you can save yourself. Once the wire is hardened it doesn't hurt to give it a good cleaning. I use some electronics grade alcohol that's 99.9%. You can use dish soap or any other method. You just want to get the wire as clean as possible to make sure there aren't any remaining residue from manufacturing. If you choose to glow your coils (which I do) then this step is more optional since any residue should burn off anyway. I still clean it regardless though.
Coils:
So your wire is ready and now you need to wrap your coil(s). Have you decided what type of build you are doing? When doing nickel builds we have to remember that the DNA40 is most effective in the .1 to 1 ohm range. It will fire below .1 but it won't be able to do so at maximum power as the current is limited. So try to stay in that range. The next step is to try to determine how you can achieve the maximum surface area for your build while still maintaining a good heat flux. If that sounds a bit complicated, it's really not. Remember our temperature is going to be limited. So the more surface area we can spread that temperature over, the more power we can put into our coils. The more power the more vapor. Now that's assuming we want the maximum power. If we don't then we just build for whatever surface area we want and verify that the approximate wattage we want to run is going to perform well for it.
So if I'm building for a kayfun that I know I'm probably going to be running about 15W. Using Steam Engine for the build I can see that if I use 28awg on a 2.5mm mandrel and do 10 wraps I can hit .13 ohm with a single coil. Steam Engine tells us two very important things. First it tells us that at 15W our heat flux is going to be 141mW/mm^2. If that number is meaningless to you, just look at the little fire symbol beside it... It scales from blue to red... You want to try to stick around the green to greenish yellow for the power you want to run. The other thing it tells us is heat capacity. I won't go into a full out discussion on this, but in general the lower the heat capacity the better. It will have less "lag time" (which isn't a problem for the DNA40, especially when running builds that won't hit high wattage anyway), but it will also stay hot longer after firing. Again not a big deal but just try to keep it low if possible. Less metal in the coil means less heat capacity, but remember you don't want to sacrifice surface area to do it. So in this case 34mJ K-1 is a little high especially with the limited airflow in a kayfun, and we may want to consider dropping down to 30awg instead, but for now we'll just let it ride.
Now suppose we were building for a dual coil RDA. And we want to get as close to maximum out of this thing as possible. We want it to utilize about as much of the 40 watts as possible while getting as much surface area as we can. So we head back to Steam Engine and play around with the numbers. Now in this case since we have a lot more room in our RDA we decided to go with a 3mm inner diameter. Using 30awg wire we can see that using 11 wraps for each coil will give us a .12 to .13 ohm coil. At 40W that's going to give us a heat flux of 196mW/mm^2. That's pretty warm, but remember we want the maximum we can get out of this thing. That's going to be about perfect. That means during a draw it probably won't drop more than a few watts to maintain our temperature with a strong draw on the RDA. If we found that it was dropping more than a few watts then we can add another wrap or two to the coils to lower our heat flux. For now this should be pretty close to perfect.
Now before we move on, I've given you two different examples here. That's exactly what they are, examples. You don't have to build these builds or match them. You don't have to use a certain number of wraps or a certain gauge of wire. What I'm demonstrating here is how to "Read the numbers" to figure out what you want to build. If you're building in an Orchid you know you can't use a giant inner diameter, if you're building in a kayfun you can't have 20 wraps. Etc... You can also use it to get an idea of what power levels that build can handle and approximately where it's going to be running (with optimum wicking) based on the heat flux. In the first example we were just building for lower wattage to get a decent vape from our kayfun. In the second example we're building a coil that can take full advantage of all the 40W the DNA40 has to offer to generate large flavorful clouds and still fit in in a smaller RDA.
Building:
Ok, so now you know what coil you want to make and your wire is ready. Time to wrap your coils. No different than building for kanthal. The one exception is when mounting. Again as covered under the issues section, even after hardening it's still fairly soft. If you are using through-hole posts for your legs, make sure the screws in the posts don't have burred edges at the bottoms. A lot of times a couple of passes on some sand paper can turn what used to be a pair of scissors into a great wire gripping machine. Also if you are having difficulty with legs getting "cut" doubling the wire on the coil leg can help. On some RDAs I've found that the center post is fine since it has two legs passing through it, but the ends want to cut. So double the end legs and let the center ones alone. Just make sure you can get them good and snug without cutting them in two. Remember you want these connections to be as tight as possible to prevent fluctuations in resistance. Even very small changes in resistance will through the TP mode off so this is absolutely critical. Spend the time to get this right and it will be greatly rewarded and save lots of frustration later.
Once your coils are in there and in place you want to be sure they are firing evenly. If you're doing a spaced coil (i.e. spacing between the wraps) they are very forgiving and require pretty much nothing more before wicking. If you're doing a micro coil (i.e. contact coil) then you need to make sure it's firing evenly. To do that you're going to want to dry burn the coil and glow it slightly. You don't want to overheat the nickel. If it gets too hot it will get a little funky (noticeable by black "globs" that form on the surface most likely carbon deposits). Turn the TP off but drop wattage down way below what you expect the build to handle. In our 15 watt kayfun build I might use 5-6 watts... for our 40W RDA build I might use 20-25W. With power reduced and TP turned off, begin pulsing the coils. As they heat up you'll see them begin to darken. Watch carrefully for any hot spots. Almost every coil I've made will have one or two wraps that fire and glow while the others don't. Keep pulsing and allow the heat to spread across the coil while keeping the glow to a minimum. Then use some pliers or tweezers to squeeze the coils (NOT while glowing). You can use ceramic tweezers to squeeze while glowing, and with kanthal builds this works WONDERFULLY... With nickel I've found it to usually cause more harm than good. Instead pulse, glow, squeeze. Wash rinse and repeat. If you have dual coils and one coil is firing before the other squeeze the one that glows first. Keep going... Eventually you'll get the coils firing evenly from the center out (on both coils at the same time if duals). Now that it's even you can turn TP back on.
Now go ahead and wick your coil. Wick it the same as you normally work a kanthal build. Once exception is when using rayon. Because the nickel is much softer it's harder to pull a lot of rayon through a coil without deforming it. If you use rayon you know that you've got to have it packed pretty tightly in the coil itself. A trick I've seen and used that works great is to divide the amount of rayon down into half, then start from both sides of the coil pulling each piece in opposite directions. This distributes the force and pulls the coil together instead of in opposite directions.
Using TP mode:
So how does TP mode work anyway? Let's talk about exactly what the DNA40 does when you fire it. When you first press the fire button the DNA40 applies wattage to the coil(s). If the coils are below a certain temperature it will put higher wattage on them, even if you have a lower wattage set. For example, if the wattage is set at 15W then it might applied 30W for just a very brief fraction of a second. It wants to raise the temperature of the coils as fast as possible. Now once the temperature is raised it will now apply whatever wattage you have set. So in this case, 15W. It will continue to do that while monitoring the temperature of the coil. If the coil exceeds the temperature you've set as your limit, then it will reduce wattage to maintain that temperature.
So if our temp is set for 450 degrees and you are firing the device while drawing the temp may only reach 380 degrees so it simply keeps the 15W applied. Now towards the middle of your draw you start easing up and not drawing as hard. Less airflow means heat builds up faster. So now the temp reaches 450 degrees at which point the DNA40 begins reducing wattage to maintain 450 degrees. When you stop drawing entirely it might only be outputting 2W. That's ok, if you start drawing hard again it will output the full 15W you have set assuming that doesn't exceed the 450 degree limit.
There is a "temperature protected" message that can flash on the screen. Through experimentation what I've found is that this only displays when there is a large differential between the set wattage and wattage TP outputs. In other words, in our RDA build that can handle all 40W pretty well. Even though through most of a hard draw it may be constantly regulating the wattage down to 35-36-37-37-39 watts to maintain the set temperature limit, it won't give you the TP message. On the other hand, if we took our kayfun build and run it will set at 40W, it's going to regulate down to 12-13-14-15 to maintain the temp limit. That's way below the 40W we have set. So now the temperature protected message is going to flash. What that means is, you don't have to be "afraid" of the TP message. It doesn't mean anything bad other than it's just doing what it's designed to do. However it can be useful. For example in our RDA build which can handle the full 40W under normal circumstances, if we start seeing the TP message flash we know that it's now regulating the wattage down below what it normal does. Which means chances are our wicks are getting dried out and it's time to redrip (unless we're purposefully trying to dry them out to switch flavors.) If you want to set the unit at 40W and leave it there you can certainly do that. Even if the unit has to regulate down to 15W to maintain your temp limit it won't make any difference. Other than the flashing TP message might get annoying. If you want to get the maximum out of your particular build you can watch (....-eyed through a mirror) about what wattage it is utilizing to keep to your temperature limit and then set around or just barely above that setting. This will ensure you're putting in the maximum power your build will sustain while preventing the TP message from flashing every time you take a hit.
One last note about TP. The DNA40 can only regulate wattage down to 1W. If you were to make a very small or very poor build, or if for example you were trying to completely dry your wicks) if the unit applies 1W and your temp limit is exceeded it will kill power to the coil until it cools slightly, then cycle back on at 1W till it's hit again. This results in a pulsing or cycling of the coil/vapor.
So what's the best way to determine where to set the temperature limit? What I do is first determine the point where my wicking material will first start to burn. So I wrap a coil and place a piece of wick in it. Set the temp to say 450 degrees and fire for 4 or 5 seconds. Then slide the wick and check it. If there isn't any browning then I know that's fine so I can bump the temp up higher. Keep repeating this until you see the wick start to brown. Once you do then you know that's the point where you're going to start to burn the wick and you should use that as an "upper limit" for your settings. So let's say you're using cotton and you find your particular cotton can handle 470 degrees before it browns. So you know you never want to go above that setting. Now as for going lower, you'll find that as you lower the temp the vape will get cooler and the taste will change a bit. I personally find that 450 - 460 is right around the sweet spot. That's way below the char point of my rayon wick, but seems to give excellent flavor from just about every juice I own. I have found a couple of juices though that seem to give a slightly better flavor down as low as 410 -420, though those seem to be the rare exception. I suspect if you typically use juices higher in PG you might find they work better with slightly lower temps while higher VG requires higher temps.
That covers the basics. I hope this has been at least somewhat helpful. Again this isn't an absolute "this is what you should do", it's simply what I personally have found to work the best. I'll come back and add more and maybe some pics or something later... For now I've wrote enough!
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