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How Do Enail Controllers Work?

25mm heat coil replacement

The big picture: starting with the heat coil​

To make things simple, an enail heating coil employs a widely used sensor called a thermocouple to give temperature feedback to the enail controller. The thermocouple component changes it’s voltage based on heat energy differences across it’s conductors. This voltage value is sent to the controller’s PID unit, and adjusted as adjusted according to the temperature which you have set. PID refers to the brains of the controller, and the heart of what keeps your enail conveniently and steadily ticking away at just the right temperature (more about PID’s later in this article).

The relay​

When the controller senses that the coil temperature is lower than the temperature you have set on the LED screen, another electrical component called a relay comes into play. A relay is an electronic component that has the ability to make or break a circuit, depending on if it has received an appropriate power signal. When the heat coil needs more heat the relay will close and allow power to flow through to the heat coil, heating it up. The relay will open back up to cut power when enough heat energy has been applied.

When the enail relay receives the signal to provide heat it bridges two paths of power together with a conductive material, allowing power to flow through. When the signal is removed, the relay lifts the bridge between the two paths, so power can no longer flow through. A relay in an enail can open and close multiple times per minute, to pulse just enough power to reach the desired temperature, or to remove enough power to drop to the desired temperature.

enail controller front

What part does a PID play in the enail controller?​

The PID can be thought of as the brains and the heartbeat of the enail, as it provides the correct amount of energy pulses to achieve the correct flow of power and heat. It regulates it’s pulses based on the voltage of the coil’s thermocouple to adjust and correct temperature on an ongoing basis. The amount of electricity going to the heat coil is determined according to this feedback mechanism. If the coil needs to cool in order to reach the set temperature, the pulses will become longer. If the coil needs to heat up to reach temperature, the pulses of electricity have longer pauses in between.

In a nutshell, PID allows for the most accurate and steady calculations of what the previous temperature was, how much energy was used, and what energy adjustments need to be made in order to hit the set temperature on your controller. The values are adjusted in real-time, taking into account external feedback. This feedback can be influenced by environmental conditions, yet still regulated in a self-learning way. In a way, one could argue that a PID controller could be considered to be an ancestor of narrow artificial intelligence.

PID is an electronic mechanism that has been widely used across many industries which require electronic values to be “steered” on an ongoing basis to meet a desired condition. The PID algo is the go-to in many industries using heating and cooling appliances besides just enail controllers. You may have guessed that most of these applications involve temperature adjustment, such as in cooking ovens, refrigeration units, etc., but did you know that many vehicles also use the PID algo for cruise control? PID has also been used in self-driving vehicles and cruise ships to keep the wheel steered in the right direction and stay on course. In fact, a PID feedback mechanism can be used for regulating pressure, weight, flow rate, or almost any other similar class of parameters in applications that involve adjusting a measured process variable to a desired set-point.

“Where does the name PID come from?”, you ask. It is an acronym that stands for proportional integral derivative. These three parameters are what combine to maintain the desired values. The parameters all work together to determine the perfect amount of energy to keep your nail at your set temperature. Now you know how your enail works, and Bill Nye would be proud.

Another fun fact: you may be surprised to know that your electronic nail controller can also be used for cooling by simply reversing the sensor wires and adding a cooling element instead of heating.

heat coil pin wiring service

What are the 5 pins on the coil plug?​

Almost every enail controller uses a 5-pin connection for the plug on the heat coil. In some rare instances you may find that the plug only has four pins, but it’s pretty rare. For 5-pin connections, you will find that two of the pins connect to AC power, two connect to the thermocouple, and one connects to ground. One common misunderstanding is that any coil with a 5-pin connection of the same size will fit any enail controller with that same size plug. The issue is that some companies chose to use a non-standard wiring to confuse the customer and make them think that they can only purchase replacement coils from the original manufacturer. Some will even misinform their customers if they ask which wiring their controller plug uses. This practice is misleading and could even be dangerous. It ends up causing more frustration and resentment than loyalty, in my experience. Check out this guide for more information about how to find a compatible coil for your e-nail controller.

Can an enail be used on a portable DC battery pack or a Euroean power source?​

Most enails that come from the US are made to run on 120V AC power. That being said, many e-nails will also accept a 220V AC power source. Check with your supplier to be sure before purchase to be sure. If the controller will accept a 220V AC power source you will also need to make sure your coil runs on 220V AC power, as well as having a compatible wiring configuration (as mentioned above). You will also likely need an adapter for the power cable that converts from a US plug to a Euro plug.   

If you want to run your enail on a portable DC battery pack, you have two options. Either you will need to get a power pack that has a built-in AC inverter or you will need an enail and coil made specifically made for DC power. DC power enails are harder to find, so your best bet is most likely going to be going with the first option with a built-in inverter. Keep in mind, if you are running a 220V setup you will need to make sure your power pack is rated accordingly.

When was the first enail made?​

Good question! I would love to know this myself. From my personal experience, I found out about enail controllers in 2015 on the enail subreddit. At the time they seemed very new and novel from what I was reading online, and I knew nobody that had one IRL. When I made my first set I was the only one in my circle that had one, and the only company that I knew of that was making them was D-Nail. A set cost well over $400 at the time. If you have any more information on the origins of the first enail, please reach out! I would appreciate any info you may have!

Conner Goertzen

Conner Goertzen

I am a DIY electronics enthusiast who has been 3D printing since 2018, making custom e-nail controllers since 2016, and putting together custom electronic instruments since 2011.

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