Using a poo-load of knowledge from this
thread over the last several months, I figured I'd share those results with my current go-to build. I've been using a variation of this for the last two months, with small refinements to help with wicking.
This is a Ni200 build for DNA40
devices, though I would imagine variations of this will work very nicely with standard Kanthal builds. I am using 30AWG, with 8 wraps around an M4 (left-hand threaded) screw which gives me an inner diameter of approximately 3.2mm and a final resistance of .20ohms every time. If I don't get .20ohms, I immediately check my connections, as I've found the Lemo to provide a consistent and solid connection every time if everything is done right (and as long as the insulator disc is flipped, see below).
First, break it all down and clean it all up. If you haven't "flipped your disc" yet, you may want to do so. What we're doing here is flipping the "disc" insulator around from it's standard factory configuration. You'll notice this piece has an indentation on one side ... rather than facing down, you want it facing up. This provides a tighter connection between the lower base/510 connection and the deck. Note that this may introduce a minor "gap" between the knurling on the base and the metal on the outer deck. It's hardly noticeable to me, but others may be more sensitive to it. I prefer the better performance of this configuration over anything else. Below is a photo of the "disc" insulator I'm referring to.
Next, re-assemble the deck. Tighten the center post / positive pin well. Sometimes when tightening, it will "spin" the positive upper deck (along with the insulator housing it) out of alignment. In order to prevent this, I use some standard pliers to hold both the upper negative/upper positive decks together tightly while tightening the positive pin. Minor adjustments are OK, just make sure that positive pin is good-n-tight.
Next, wrap the coil. I use a left-hand-threaded machine screw (M4) with a homemade jig, one end of the wire tight around a mounting point on my jig (the screw you see in the photo), and the other end of the wire clamped (I use vice grips) to a solid object with the wire at the clamp point wrapped around a piece of garden hose gasket to keep it nice and tight/prevent the vice grips from simply cutting or flattening the soft Ni200 wire. Keeping constant tension, turn the tool to wrap the coil. After wrapping the coil on the jig, cut the wire (leaving enough lead length), and remove it from the jig. I then spin the coil back on to a second left-hand-threaded M4 machine screw in order to prepare for mounting. Before mounting, I typically pull the leads nice and tight just to make sure there is no slack and the coil is still very tight around the screw. Below is a photo of my home-made jig made from an old laundry basket handle (why not?)
Next, mount the coil. Nothing to tricky about this, except 30AWG Ni200 is easy to break, don't tighten too much or it will snap and you will inevitably curse. Ready to mount the coil:
Photo of mounted coil:
For my (roughly) 3.2mm inner diameter 8 wrap coil, I take a 4mm x 40mm piece of KGD cotton and strip the harder outer pieces off, leaving just the fluffy center. There is a bit of debate on this; some claim it's OK to leave the outside on (would have to cut the piece smaller, probably 2-3mm). I find that if I remove the outer / denser layers, I get less popping and the fluffy cotton "fills" the coil a little better. Here I am removing one of the outer layers:
Pinch and roll one end, and pull on through. There should be very little resistance.
I like to trim to just inside the outer diameter of the Lemo base, shown here:
Now, the part that has greatly enhanced my wicking properties and has allowed me to vape at much higher wattages: Take some off the top! I was previously using way too much cotton, both through the coil and at the wick ends. I cut at an upward angle from the ends of the wick up to just in front of the beginning of the coil, leaving prominent shoulders. I find thinning out the ends helps deliver liquid faster to the coil, and also cutting from the top as explained helps to keep the cotton away from the juice channels.
Next, juice it up:
Gently lower the wick ends to brush the top of the lower deck. I use a precision micro flathead to do this. It's difficult to see in this photo, but the juice channels and threads are 100% clear and the wick is actually curling inward a bit towards the insulator. The wick is touching the smooth portion of the deck only (with maybe a small portion touching the bottom of the insulator).
Next, bridge the wicks using @WeirdWillie bridging method. Still not exactly sure how/why this works so well, but my primary reasoning is for enhanced/richer/deeper flavor notes. It also seems to help keep the coil well-fed.
Now comes another very important part: leak prevention. I lubricate all of the seals with e-liquid, and pay special attention to the chimney seal. Photos to explain, first up: lubricating the lower clear ring:
Now, lubricate the slot for the black chimney o-ring:
Install the black chimney o-ring, make sure it's not twisted or bunched up anywhere. Then add more e-liquid (lubricant) to the o-ring:
Still paying attention to the chimney o-ring, I now test fit it and tighten/loosen a few times in order to make sure it's sealing well. It should feel smooth and well-lubricated when doing this. If it feels choppy, jumpy, or like it's "stretching" the rubber, add more e-liquid and try again. I've found this seal to be crucial to the overall successful operation of the Lemo.
Time to take care of the top cap ... insert the large clear ring, make sure it's seated properly and lubricate it with e-liquid as well:
I like to spin the glass on the newly lubricated seals in the top cap and the base before tightening down. In the following photo, I'm doing this on the top cap. Do it on the bottom as well.
Now, tighten everything up. Once everything is threaded and starting to get tight against the seals, give the glass a couple of more spins before one last final torque down. Not too tight. Your glass may even still be able to spin slightly with all that e-liquid lubrication (I typically tighten to just beyond the point of being able to spin the glass).
That's about it. The rest is fill and vape. Be sure not to fill all the way: leave a bubble to support proper vacuum. Vape it hard a few times right after tightening everything down to build up some vacuum, you should eventually see some bubbles coming up immediately after each pull which indicates things are working properly. Enjoy!
