How to Build an RDA Coil
Getting into rebuilding seems like a huge step to take. Instead of simply replacing pre-made atomizer heads, you have to take a more hands-on approach, and that means tackling some initially scary-looking devices head on. So how do you build a coil for you new rebuildable dripping atomizer (RDA)? What do the posts do? What do you need to get started? Here’s everything you need to know to get started building an RDA coil.
Anatomy of an RDA
RDAs all have a very similar layout. Under the top cap (the metallic outer cover on the atomizer), you’ll see an array of posts, usually with screws in the top and holes through their center. The central post is the positive connection, and the outer posts (sometimes there’s just one) are the negative connections. Connecting the positive and negative posts with a coil allows current to flow when you press the fire button, and that’s what vaporizes your e-liquid.
The remainder of the RDA doesn’t take much explaining. At the bottom of the posts, the “juice well” is surrounded by the lower metallic lip of the device, enabling it to hold more e-liquid than your wick could soak up alone. The only other thing you really have to consider are air-holes: just make sure your air-hole is right next to your coil when you’ve built it and you’re good to go. Depending on your device, it might have an option to close off some air-holes, but this is normally simple enough to operate.
What You Need to Build an RDA Coil
You’ll need a few things to get started with rebuilding. First, ensure you’ve got a supply of kanthal or nichrome wire. The general rule is: the thicker the wire (lower American Wire Gauge – AWG – number) the lower the resistance. As a general rule, 28 to 32 AWG wire is a good place to start. If you want to build a micro-coil (recommended for performance, but a little more difficult to build), choose a lower-gauge wire (28 AWG, for example), but for a standard coil higher gauges ensure you end up with a high enough resistance.
You’ll also need some wick material. There are quite a few options here, but for affordability, flavor and wicking ability, 100 % organic cotton balls are probably the best way to go. You should boil them in water and let them dry out before using to remove any unwanted residue from manufacturing (this is probably not strictly necessary, but since you’re inhaling from it, it’s better to be safe).
Finally, a few tools are essential for getting the process completed smoothly:
- A screwdriver. You’ll need something to loosen and tighten up the post screws, and if you get a precision screwdriver set, you can use one as a guide for building your coil too.
- Some tweezers or pliers. If you’re building a micro-coil, tweezers or pliers are essential for compressing it and getting all of the wires making contact with each other.
- Wire cutters, scissors or nail clippers. You’ll need something to snip your resistance wire and wicks with to keep everything neat. Nail clippers are pretty good for this, but anything suitable will do the job.
- Ohm reader, multimeter or a VV/VW mod with resistance checker. It’s good practice to check the resistance of your builds before you fire them. While most modern devices can take any reasonable resistance (and will refuse to fire anything below around 0.2 ohms), this is another area where it’s better to stay safe.
Building Your RDA Coil
- Step 1: Snip yourself off a generous amount of wire. Kanthal is cheap, so don’t skimp on the length: go for around four inches so you have plenty to work with. It’s better to cut too much than not enough.
- Step 2:Choose a precision screwdriver, drill bit or anything else cylindrical and relatively small in diameter (anything 1/8 inch down to 1/16 inch works well) as a guide for building your coil. This helps to keep everything steady as you build and ensure you have a coil with a uniform diameter.
- Step 3: Hold your wire against your guide in preparation for wrapping. Don’t start right at the end of the wire – leave an inch or so spare, with the remaining wire ready to be wrapped.
- Step 4: Start wrapping your coil. Holding the guide steady with one hand (and keeping your wire in place), start to wrap the wire around the guide, keeping it taut as you do. For standard coils, the aim is to keep each successive wrap quite close together but with even spacing between them. For micro-coils, the aim is to get each successive wrap as close to the previous one as possible (without overlapping), taking it slowly if you need to so the positioning is right.
- Step 5: Keep wrapping your coil and count the number of turns as you do. The more wraps you do, the higher your resulting resistance. Although low resistance is often the goal for rebuilders, if it’s your first time there’s no need to worry about this so much. For standard coils, five wraps is standard. For micro-coils do around 9 or 10 wraps and your resulting resistance will be somewhere between 1.5 and 2 ohms.
- Step 6: When you finish, the end of the wire will start to unwrap a little, so give it an extra half-turn before letting go. The aim is for both of the wire-ends to be pointing in the same direction.
- Step 7: Look at your coil. For standard coils, you’re looking for even spacing between each wrap – you can adjust any wraps that look a little uneven. If you’re going for a micro-coil, there will probably be several visible gaps between the successive wraps at this stage: this is OK, but if you can pinch them closer together, it will make things easier a little later.
- Step 8: Unscrew the positive and one of the negative posts on your RDA. This will reveal the holes through the center of the posts, and this is where you have to thread the ends of your wire. Keep your coil on your guide as you connect it: this will make it easier to position correctly. It’s a little easier to get both ends through the holes if they’re slightly different lengths (then you can focus on one at a time rather than both together), so trim one of the ends if needed.
- Step 9: Position your coil so it doesn’t touch the posts, leaving some space between it and the sides of your atomizer. If your coil touches the body of the atomizer or a post, this can create a short circuit and cause problems when you fire your device. When everything is positioned correctly, tighten up your post screws and remove your guide.
- Step 10: Test your resistance. If you have a 510-threaded ohm reader, you can do this easily by screwing your atomizer in place and checking it, or you can just attach it to a mod with a resistance checker. It doesn’t really matter if your resistance is higher or lower than what you were shooting for, as long as it isn’t way too high or low.
- Step 11: Test-fire your coil. You’re looking for an even glow, ordinarily starting in the center and spreading out as you continue firing. For ordinary coils, if your spacing is even, it should all work as intended, and if not, use some tweezers to re-position any wraps not heating up. When it heats evenly, you can move on to step 14. If you’re building a micro-coil, at this point you’ll likely notice that not all of the wraps heat evenly – this will change after you’ve compressed the coil with tweezers.
- Step 12: For micro coils only: fire your coil five seconds or so, so it glows red and gets hot, and be ready with tweezers. After you’ve released the fire button, compress the coil from either end using your tweezers, just hard enough so the wraps all make contact with each other. Hold it in this position for five to ten seconds.
- Step 13: For micro coils only: Test-fire your coil again, looking for an even glow. The aim is for the glowing to start in the center of the coil and gradually spread to the outer ends. If it still heats unevenly or it still looks like some of the wraps aren’t making good contact with each other, heat and compress the coil again, as in the previous step.
- Step 14: When your coil is heating up like it should, you can snip the free ends of wire at the opposite side of the posts. It’s better to do this as close to the post as you can, but don’t worry if you leave a little bit poking through. As long as they aren’t touching the posts, the base of the atomizer, each other or the sides of the atomizer you won’t get a short.
- Step 15: Insert your wick. If you’re using cotton balls, pinch a long section off the bulk of the ball. Try to make it so the diameter of the section you remove is a little bigger than your coil, and avoid pulling off a very tightly packed section. It might take a bit of trial and error to get this right, but thankfully cotton is cheap.
- Step 16: Twist one end of the cotton in your fingers. This will create a thin “sharper” end you can thread through the coil more easily. Poke your cotton through the middle of your coil and pull the end from the opposite side. Pull the wick through as much as you can, being wary of forcing it too much and misshaping your coil in the process: if you encounter resistance, pull it back out, make your wick a bit thinner and try again.
- Step 17: Snip off any excess cotton. There’s no hard and fast rule, but you’ll probably have too much cotton when you first pull it through, so snip off the ends (using the edges of your atomizer as a guide is a useful tip). You can now move both ends of the wick onto the base of the atomizer, ready to soak up juice.
- Step 18: Drip some e-liquid onto your wick (making sure it’s thoroughly soaked) and get ready to vape. You can test-fire when you’ve soaked the wick with liquid to watch your new coil produce its first vapor – not necessary, but a proud moment you should savor.
- Step 19: Replace the top cap and vape away!
This is just a basic guide to getting your first coil built: there is a lot more to explore, from dual coils to vertical coils, Clapton coils and much more. The good news is that what you’ve just done represents the core skill that you can continue to develop as you get used to rebuilding. Even if you struggled this time, don’t worry about it! We’ve all been there, and the more you practice, the easier it gets.
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