The Beginners Guide to Coil Building

Published by Paul Larter on 5th Jul 2016

Coil Building: A Beginners Guide

All the UD vaping tools

Rebuildable Dripping Atomizers (RDA’s) and Rebuildable Tank Atomizers (RTA’s) allow the user to make their own coil(s) (the heating elements) and wick to the user’s personal preference.

Rebuildable atomizers are popular as a good build will almost certainly exceed in flavour & vapour production over a similar atomizer with a pre-made ‘drop-in’ or ‘screw-in’ coil. However, there are many variables, and we hope to get you started on the right track here.

In this guide we will discuss:

  • Tools
  • Wire types
  • Determining which type of coil to build
  • The build
  • Wicking
  • Mod Settings
  • Eliquid
  • Safety advice

We highly recommend learning to build using a RDA as it will be far easier to build on. We will make a single & dual coil build on the UD Hunter RDA. The UD Hunter is very easy to build upon. It’s a good quality, cost effective & a good ‘all-rounder’ for both flavor and vapour production too.

UD hunter            Hunter RDA by UD

Tools

You will need:

  • Resistance Wire
  • Wicking Material – Organic Japanese Cotton
  • Coil Jig (Screwdriver, post or drill bit)
  • Screwdriver for the RDA’s screws (included with most RDA’s)
  • Tweezers (preferably ceramic tipped).
  • Wire cutters
  • Scissors
  • Ohmmeter
  • E-juice

Wire Types:

Kanthal A1 wire is the most commonly used wire for all rebuildable atomizers. NiChrome is also quite popular and is quite similar, however it has a slightly lower resistance.

There are several other wire types including numerous twisted and Clapton wire. These are primarily for the more advanced users. Stainless Steel, Nickel & Titanium are most commonly used with temperature sensing builds. (Please see our Blog: What is Temperature Control), and again, are reserved for the more experienced coil builder.

We recommend using Kanthal A1 and this is the wire that we will use in this guide.

Determining Which Type Of Coil To Build:

Single Coil or Dual Coil?

This question will ultimately be answered by the atomizer and Mod that you are using. Some devices such as the UD Hunter will allow for both a single or dual coil to be fitted. A dual coil build will usually offer much more vapour production upon exhale and flavor can be increased. , however your Mod will need more power to run it.

Wire Gauge or AWG (thickness) or type?

The more thick the wire is, the more power will be required to heat it. It will also lower the final resistance of the build. The decision will be determined by the space available in your atomizer and your mods parameters. We recommend starting with either 28AWG or 26AWG wire.

Resistance?

The Flavour profile and vapour production can change quite significantly depending on the final resistance of your build. It goes hand-in-hand with the wire material, gauge and type or style of wire fitted. As a good rule of thumb, the lower the final resistance, the more vapour production there will be. Very low resistances (0.5 Ohm or below), will tend to trade flavour quality for more vapour production and a warmer vape temperature.

Most importantly, it will depend on the Mod you are using.

  • Regulated Mods: With a regulated Mod, the user must refer to the manufacturer’s operating instructions. Here you will find the correct operating range for resistance that your Mod will support. Most devices support between 0.5 Ohms - 2 Ohms, however, some Mods will support much lower resistances. It is important to enure your final resistance sits in between the Mod manufactures parameters. With a Regulated Mod, the user will be able to turn the power up or down which in turn will alter the amount of vapour production. Regulated Mods also offer a wealth of safety protection built into the circuits.
  • Mechanical Mods: We do not recommend using a Mechanical Mod if you are new to coil building. Why? Mechanical Mods are simple devices without any control over the power output. The output or power is governed by the principles of Ohm’s Law. Simply put, lower the final resistance of the coils fitted to the atomizer, the more power will be drawn from the battery. As most Mechanical Mods do not have any in-built safety protection, it is extremely important to use very good condition, high quality batteries. By using Ohm’s Law, the user can determine the final amount of current (Amp) draw. This should never exceed the Amp rating of the battery being used. Finally, an Ohmmeter must be used to check the final resistance is correct and to ensure there are no short circuits.

The Build

We recommend using Kanthal A1 and in this guide we shall use a thickness of 26 AWG / 0.40mm.

Most wire comes on a spool that can be cut to the desired length. By using a coil jig, a screwdriver, post or drill bit, the wire can then be ‘wrapped’ or ‘turned’ into a coil. The diameter of the post and the number of wraps turned will determine the final resistance of the coil. More wraps there are, the higher the resistance will be.

We are going to make a single 1 Ohm coil and a dual 0.5 Ohm coil build.

At Vapetime we highly recommend using an online resistance calculator. We use www.steam-engine.org. We also have this and Ohm’s Law tools easily accessed within our Vapetime App under ‘Tools’. Simply enter your desired final resistance and fill out the parameters to establish the amount of wraps required.

  • Single Coil (1 Ohm):
  • Using Steam-Engine Select: Kanthal A1, 26AWG, Single Coil, 1 Ohm target resistance.
  • The’Inner diameter of coil’ is the post size that the coil will be wound onto (In this case 2.5mm). The leg length will be approximately 5mm.
  • The number of wraps required to make a single 1 Ohm coil will be approximately 8 wraps of 26AWG Kanthal A1 on 2.5mm post.

Please view the screenshot below:

  1. www.steam-engine.org

  • Dual Coil (0.5 Ohm):
  • Most RDA’s and RTA’s are of a parallel circuit. Following Ohm’s Law, for every matching coil you add to your atomizer, the final resistance will be halved.
  • Example:
  • 1x 1 Ohm = 1 Ohm final resistance.
  • 2x 1 Ohm = 0.5 Ohm
  • 3x 1 Ohm = 0.333 Ohm
  • 4x 1 Ohm = 0.25 Ohm

Fitting two 1 Ohm coils into the UD Hunter RDA will result in a final resistance of 0.5 Ohm.

When wrapping or winding the coil, try to ensure that each wrap is close to one another. By far the quickest, easiest and most successful method of making consistent coils is to use a dedicated coil jig.

Please watch the video below that demonstrates the UD Coil Jig V3 including a brief overview of Steam-Engine resistance calculator.

UD v3 coil jig

https://www.youtube.com/watch?v=q3zw4xb1t5k

If the above sounds a little daunting, don’t panick! At Vapetime, we do have pre-made coils that are made to a specific resistance and are ready to be fitted to your atomizer.

When positioning the coil, always ensure that the coil is centrally placed as possible. The coil(s) should only be in contact with the positive (centre) and negative (outside) posts and not the tank or RDA walls or other components. Using a screwdriver, drill bit or post from the coil jig is a great way to position and support the coil whilst fitting.

coil fittingscrewing down coilcoil positioning

By using the Hunter RDA top cap, ensure the coil height will be in line with the airflow slot. When happy with the positioning, trim the access wire with wire cutters.

coil building1coil building 2coil building 3

Using the Ohmmeter supplied within the UD Coil Mate tool kit, we can confirm the resistance of the coil. We aimed for a 1 Ohm resistance using the Steam-Engine resistance calculator. The final resistance of one coil is 1.03 Ohms as can be seen here.

ohm meter

Once the coil is fitted, you will need to oxidize the coil. This will anneal it and make it stronger. It will also burn off any residue or dirt on the coils. With approximately 20-30-watts of power, gently pulse the coil by pressing the fire button intermittently until it starts to glow. Using Ceramic Zirconia tweezers (to avoid short circuit and heat transfer), the coil(s) position can be tweaked and tidied. Each wrap of the coil should heat evenly. If they do not, take your tweezers or a small screwdriver and gently ‘strum’ the coils whilst they are hot and then pulse again. They should then heat evenly.

coil positioning ozidizing your coil

When fitting dual coils, fit the second coil and repeat. Ensure that both coils heat up and glow evenly. If they do not, you will need to re-seat the coils by unscrewing them from the atomizer and re-fitting. This will ensure that both coils are receiving the same conductivity and therefore the same amount of power.

Wicking

There are different materials that can be used for wicking in rebuildable atomizers. However, we highly recommend using Organic Japanese Cotton.

Vapetime stocks Muji, Koh Gen Doh and Kumo Organic Japanese Cotton. Importantly, the cotton is clean and processed without the use of bleach or other harmful chemicals.

When wicking with cotton, it is important to always cut the cotton strips along the grain, and not across it. This will aid wicking significantly. Ensure that the cotton feels ‘snug’ and not too loose when fitted to the coil. The cotton should have a medium-firm contact with the coil.

The cotton ends or tails should be spaced and fluffy. This can be achieved by pulling the cotton apart slightly either before or after wicking, and then by using a cotton hook or fine tweezers. The more ‘fluffy’ the cotton, the better it will perform. There are many YouTube videos demonstrating the ‘Scottish Roll Wicking Technique’. It is a fantastic method that requires the cotton pad to be stretched apart as much as possible before being rolled and then fitted to the coil.

coil wicking

The length of the cotton ends/tails should be just long enough to sit into and touch the bottom of the juice well.

Wicking your coil

Too much cotton will reduce the rate at which the cotton will be able to wick. Also, the wick should not obstruct the airflow around the coil. The cotton wick can be positioned quite easily with the use of some tweezers and/or a cotton hook.

Wick position

That’s it! Built!

Now place the top cap on with the airflow slots positioned closest to the coils. Check that both coils will be directly in line with the airflow.

Mod Settings

For this example, using the wire & build shown, we recommend using:

  • Single 1 Ohm coil - 20W-30 Watts
  • Dual 1 Ohm (0.5 Ohm final resistance) - 30W – 50 Watts

E-liquid

Most rebuildable atomizers (drippers & tanks) perform much better with higher levels of Vegetable Glycerin (VG) content. High VG eliquids will offer much higher levels of vapour production. 50% VG levels or higher are ideal.

Nicotine Strength. Due to the performance and quantity of vapour production, much lower nicotine levels are advised. 3 mg is most commonly used and offers a very smooth experience. It is the ideal strength for vapers that would normally use upto 12mg nicotine. 6mg will offer a robust throat hit and would suit a 12mg – 18mg mouth-to-lung inhale vaper. Vapetime does not recommend the use of higher nicotine levels. The exception to this rule is for a heavy 24mg user with a very good clearomiser or mouth-to-lung inhale tank.

Safety Advice

By following the above guide will provide you with the best practice for safe and accurate coil building. However, there are safety points below that should always be adhered to.

Batteries:

New, excellent condition batteries designed specifically for vaping should always be used. Never use old, damaged or fake (clone) batteries. Always source batteries from a reputable supplier. If the batteries get hot, always stop using the device and inspect. With mechanical mods, batteries will need to be replaced frequently, particularly if used with very low resistance builds. If the batteries become hot when used in a mechanical device, stop using immediately.

Always store batteries in a secure battery container or sleeve. Do not leave loose in a bag or pocket.

Resistance.

Always make sure the resistance of your atomizer is within the operating limits of your regulated mod. With mechanical mods, ensure the final resistance will not draw more amps than stated within the mechanical mods specifications. (using Ohm’s Law calculator on Steam-Engine.org, enter your batteries nominal voltage and atomizer resistance to establish current draw).

Always check your resistance before use. Most regulated mods display resistance although an Ohmmeter is usually more accurate and is cheaper to replace if things go wrong.

Check your coils:

After the first couple of uses, the coils will have heated, expanded and retracted. It is highly recommended to check that the coils are still securely fitted to both the positive and negative posts.

Safety Fuse:

Most good quality mechanical mods can accept a safety fuse. For peace of mind, we highly recommend using them. It will help to protect against damage or harm to self and equipment through short circuits and battery failure.

If you need any guidence on what dripper might be best for you or how to nail any specific types of builds or experiences, we are always available to help advise and optimise your experience. 

Please reach out on Tel: 0203 3718184 or email us to enquiries@vapetime.co.uk

Happy Dripping!