A little while back somebody handed me a stack of photocopied pages from 1978. A doctor named Andrew John Lemes the third put together his own manual back then called Tattoo: State of the Art, hand drawn diagrams and all, laying out exactly how a coil machine works and how you actually tune one. This was not a manual on how to build a machine from scratch, no frame casting or coil winding recipes in here. It was about the function, understanding what is actually happening inside the machine and how to run it right. No forums, no group chats, no builders comparing notes online.

Worth saying plainly, Lemes was not really supposed to be putting any of this out there. Machine building was guarded territory back then and builders kept their numbers to themselves, so a doctor writing it all down in his own manual and passing out copies was not exactly welcomed by everybody in the business. That is probably why it never went further than a stack of photocopies handed from one person to the next instead of something anybody could actually buy.

What strikes me now is that the same information matters more today, not less. Tattooing has gone from something people hid to something people take seriously, with real standards around sanitation, safety, and actually understanding your own equipment. None of that belongs locked away anymore. It belongs right here, out in the open, where any artist can put it to use.

Back then you had to actually be a technician to get ink into skin at all. Nothing came premade. You built your own needle clusters, wound your own coils, cut your own springs, and if you did not understand what was happening inside that machine you were not tattooing for very long. Knowing this stuff was not optional, it was survival. Fast forward to today and none of that is true anymore. You can buy a machine, buy your needles, buy your cartridges, and never once think about what is happening inside the coils. But if you do take the time to actually understand it, you will be a better artist for it, plain and simple.

Let's be honest about something else too. Tattoo machine tuning has always carried a bit of mystery to it, and a lot of that knowledge stayed guarded on purpose, for good reason. It takes years of trial and error to actually understand what makes a machine run right, and that kind of hard earned knowledge does not get handed out carelessly. But there is a real difference between protecting hard earned expertise and leaving the artist who already owns the machine with no idea how it actually works. This is a hand applied craft. You are the one holding it, feeling every hit, making every pass. Understanding your tool is not optional in a craft like this. It is part of the craft.

There is a practical side to this too. Artists talk, and what we hear constantly is frustration with how long it takes to get a machine repaired and how hard it can be to get a straight answer out of customer service once something breaks. When you do not understand what is actually wrong with your own equipment, you are stuck waiting on somebody else's timeline, and that is real money and real appointments lost. Two things fix that. One is knowledge, being able to look at your own machine and know what is actually wrong with it instead of shipping it off and hoping. The other is who you buy from in the first place. Companies actually built and run by tattooers tend to answer the phone, understand the problem, and treat your downtime like it matters, because they have sat in your chair.

That is the whole point of this guide. It comes down to a handful of variables, spring tension, resistance, geometry, alignment, and every one of them behaves the same way every time you set it the same way. I have spent years building, tuning, and fixing these machines, and this is everything I know about doing it right, laid out the way I wish somebody had laid it out for me the first time I ever picked one up.

So let's start with the basics. Here is what is actually happening inside a coil tattoo machine every single time it fires, and everything that goes into keeping one properly tuned.

The Mechanical Cycle

There's no motor in a coil tattoo machine. The coils themselves act as an electromagnet, pulling the armature bar down and releasing it the instant power cuts. That cycle, happening dozens of times a second, is what creates the machine's signature tone. Two things most artists overlook are the rear gap, the space between the armature bar and the rear coil, and armature bar rocking, a small torquing motion on every cycle that can throw off tone even when spring tension and voltage are dialed in correctly. The armature bar needs to strike the front coil properly and square. If the bar is rocking and clipping the rear coil instead, that's where chatter comes from, an inconsistent, rattling cycle that shows up as tone problems even when the front of the machine looks dialed in.

Coil Quality and Material

Bad coils can make a tattoo machine run like absolute dog shit, and it almost always comes down to core material. A high carbon content in the coil core kills performance because it holds onto magnetism instead of releasing it cleanly. That's why we spec the finest grade low carbon iron alloy we can source, matched to an armature bar that completes the magnetic circuit without inducing hysteresis, so the field collapses fully on every cycle instead of choking the circuit down.

The Three Tuning Variables

Spring Tension

Spring tension controls power and hit depth, tighter for a sharper hit, looser for a softer one. Springs only get replaced when they're actually broken, not on a schedule. Adding tension is part of tuning, not a sign of wear. Most quality springs are made from either 1075 or 1095 carbon spring steel, and the difference matters. 1095 has a higher carbon content, giving it more snap and a faster return, but it's less forgiving and can fatigue quicker under heavy tension. 1075 is slightly softer, more forgiving over long sessions, and holds up well under repeated flex.

Spring longevity comes down to more than the steel itself. Over-torquing the screw that mounts the rear spring to the spring deck is one of the most common ways to cause premature spring breakage, that hardware needs to be snug and consistent, not cranked down. Springs that aren't properly deburred and smoothed are also prone to fracturing early, a burr is a stress riser, and a spring will fail at that point long before it fails anywhere else. And it's not just the machine. Your tattooing setup itself can break springs prematurely, the needle jiggling too much on the armature bar, rubber band tension that isn't properly adjusted, or simply tattooing too hard, all put extra load on that spring cycle after cycle. How the needle interacts with the tube, and the type of nipple used on the end of the armature bar, factor into this too. Consistency and maintenance matter as much as any single spec. I practice this in my own tattooing and log every spring, every setup, every failure, and I'll be putting that log up as a downloadable PDF on the site.

Resistance and Contact Screw Material

Resistance builds up over time as contact points oxidize, which is why a machine that ran great at 7 volts for months can suddenly feel weak. Keeping your contact screws clean is essential to staying ahead of this. Material matters too, silicon bronze and semi-hard alloyed silver are the only two contact screw materials I recommend. Brass, copper, and steel are inferior in my opinion and cause erratic-running machines.

Geometry and Armature Bar Alignment

Geometry is the ceiling on everything else. A bent frame or misaligned bar channel can't be fixed with tuning alone, which is why CNC machined frames hold their tuning better than cast ones.

Electrical Fundamentals

Your power supply converts AC to clean DC, and a poorly regulated one leaves ripple that shows up as inconsistent performance no amount of tuning can fix. The capacitor absorbs the electrical kick every time the circuit breaks, protecting your contact points from pitting. Your clip cord matters more than people think. Frayed internal wire adds resistance you can't see from outside the jacket.

Tools and Hardware

Using the right tool matters as much as any tuning adjustment. A lot of damaged screws and stripped hardware comes down to artists grabbing whatever screwdriver is lying around the shop instead of the correct size and blade for the fastener. Knowing the terminology is the starting point. A fillister head slotted screw is not the same as a round head or a binder head slotted screw, and each one seats and drives differently even though they all take a flathead driver. Using the wrong flathead width on a fillister head screw is one of the most common ways people chew up a slot that was never actually damaged before they touched it.

Machines with hex hardware need the correct Allen hex key size, not the nearest one that sort of fits. An undersized hex key rounds out the socket almost immediately, and an oversized one will not seat at all. Keep a full set on hand, in the small increments machine screws actually use, not just the handful of sizes that come in a generic kit.

Understanding thread specs matters just as much, including an 8-32 tap for machine work. Knowing which tap matches which hole, and re-tapping cleanly when a thread is damaged instead of forcing an oversized screw into it, is part of keeping a machine's hardware in good condition long term. Building out a proper toolkit, correct drivers, the right hex keys, the right tap, is worth the investment.

Precision Measurement

Maintaining a machine at a high level means being able to measure it, not just feel it. A micrometer is what separates a real adjustment from a guess. Knowing how to find the centerline of the frame, and measuring off that centerline consistently, is what makes alignment repeatable instead of eyeballed. Small deviations, a few thousandths of an inch, are invisible to the eye but show up immediately in how a machine runs, so being able to actually measure gap, bar straightness, and spring position against a true centerline is a core skill, not an optional one, for anyone doing real precision work on a coil machine.

Builder Versus Technician

These two terms get used interchangeably, and they shouldn't be. A tattoo machine builder designs and manufactures machines, frames, and components from raw material, machining parts, engineering geometry, and creating something that did not exist before. That means sourcing or specifying materials, cutting frames on a mill or CNC machine, setting tolerances, and making the design decisions that determine how a machine will perform before it ever gets tuned by anyone. A builder is responsible for the ceiling, the geometry and material quality that every future technician will be working within.

A tattoo machine technician works on machines that already exist, tuning, repairing, maintaining, and restoring them to correct running condition. A technician does not need to know how to machine a frame from billet, but they do need to understand diagnosis, how to read a symptom back to its actual cause, whether that is spring tension, resistance, contact point wear, or a geometry issue the builder baked in. A technician's job is to get everything the machine is capable of out of it, within the ceiling the builder already set.

A builder needs to understand manufacturing tolerances and design intent. A technician needs to understand diagnosis and maintenance. Plenty of people are both, especially in a shop like ours, but the skill sets are genuinely different, and conflating them undersells what each one actually takes to do well. Respecting that distinction is part of respecting the craft on both ends.

Maintenance

Wipe the machine down after every session. After using a disinfectant like Cavicide, neutralize the chemical, then oil the machine to keep it in good working condition. Check contact screws for pitting or buildup regularly, and make sure there's no corrosion. Don't over-tighten binding posts, but don't leave them loose either. Keep the machine dry, moisture is one of the fastest ways to get inconsistent performance or corrosion. Keep a simple log of voltage settings so you catch drift early instead of after it shows up in someone's skin.

Troubleshooting and Common Questions

Why does my machine sound different from my friend's machine even though we bought the same model?
It comes down to variables like spring tension and overall alignment, since each machine gets assembled slightly differently. Worth inspecting how the armature bar meets the front coil, the rear gap between the rear coil and the bottom of the armature bar, and spring tension, to make sure the hardware setup is repeatable machine to machine.

How do I know if I should tune my machine myself or send it to a technician?
For someone learning, it's smart to have machines tuned or rebuilt by a builder you admire, Feldman Tool Co. included, as a learning reference. As you acquire the tools and knowledge, you build the confidence to become your own technician. It's a progression, not a hard rule.

How often should I actually be tuning my machine, every session or just when something feels off?
Preventative maintenance roughly once a month to a month and a half depending on usage, cleaning contact screws and confirming spring tension holds steady. A spring tension gauge helps, but feel works too once you've trained for it. On top of that, there's reactionary maintenance whenever something starts to feel off.

My machine feels great for lining but terrible for shading, or the other way around, is that a tuning problem or do I need a different machine?
Typically you use different machines for different techniques. I don't subscribe to the idea that one machine should do it all, I don't think that's fair to the tattoo artist. Every craftsperson uses multiple tools to do excellent work.

I've only ever run rotaries or cartridge pens, why bother learning coils?
A coil is a self-regulating mechanical device, tried and tested and true to the craft. It gives you the leverage to maintain your own tools, whereas with a pen or rotary you're at the mercy of the manufacturer, domestic or overseas, which isn't always convenient and can leave a bad taste in your mouth if their customer service falls short.

What's the biggest mistake people coming from cartridge pens make when they first pick up a coil machine?
A lot of it is psychosomatic. The artist has to go in with the right mindset for the machine to work properly for them.

At the end of the day, whether it's a rotary, a coil, a pen, or a hybrid, the machine only has to go up and down to do the job. But there are minute details that set these things apart, and you can make a mistake going in either direction. Knowledge is the deciding factor.

It's worth saying plainly, machine preference across rotary, coil, pen, and hybrid styles is largely ad populum. Opinions get passed from one tattooer to the next, and that word of mouth shapes what people believe is better, based on opinion rather than settled fact. It's always been my belief that your own experience and knowledge give you the confidence to try something new, and an opinion earned that way holds up far longer than one you borrowed just because it worked for somebody else. Understanding the concepts, the basics, and the technical aspects gives you predictability instead of just following the crowd.

Bottom Line

If your machine feels off, you're not undertooled, you're under-tuned. Understanding what's actually happening inside a coil tattoo machine, the mechanics, the materials, the electrical fundamentals, and the maintenance routine, is the difference between fighting your equipment and working with one.

By Brandyn Feldman, Feldman Tool Co.

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