What does Machine Springs and Coils actually do, and
How strong do Machine Springs and Magnetism need to Be?

The answers to these questions, is probably the most important information about a tattoo machine that a tattooer needs to understand, yet is undoubtedly some of the most misunderstood information concerning the components and operation of a tattoo machine.

The most common answer to the first question seems to be;
To return the points to the closed circuit position as fast as possible, so the coils can be recharged with the electrical current that generates the magnetism.

This answer is only partially right, tremendously misleading, and grossly misunderstood.

The very first duty of the (rear) main spring is actually to pull the needle points from the skin, and in reality, only needs to be strong enough to do that. The main springs other duties are equally important, they hold the needles firm while allowing them to freely move in a very controlled, predictable, and repeating manner.

Repositioning the front spring and contact point to close the electrical circuit is a secondary action of the main spring, but albeit, necessary for the circuit to be complete and the cycle to repeat. But this fact and function is only a favorable coincidence, certainly not the main duty of the rear spring.

The front springs duties are slightly different, other than completing the electrical circuit that charges the magnet (coil cores) and helping the machine run smoothly, they have little to do with the actual penetration of the needle group going into the skin, and nothing to do with the needles movement out of the skin. The front spring of a properly tuned machine is actually nothing more than a shock absorber for the arm-bar. Being a contact point for the on-off switch is secondary.

Spring tension of both front and rear springs do have a combined effect on the "speed' of the tattooing process, but not in the most commonly understood method. The first issue of "higher than necessary spring tension" that needs to be understood is, high spring tension of either front or rear springs creates excessive force of the machine. Each spring has it’s own unique effect on the machines operation. But the effect of higher than necessary spring tension of either spring creates the need for excessive lateral hand speed. High hand speed becomes necessary to prevent overdose spots in the skin, but high hand speed also reduces detail and causes skin damage.

High spring tension increases the speed of the machine by first creating the need for the high magnetic force necessary to overpower the spring tension. If it takes more magnetic force to overpower the spring tension than the force necessary to push the needles into the skin, the needles will slam into the skin at a higher speed and force than necessary. A short stroked machine compounds the problem.

High (main) spring tension then creates a fast action on the needles return (pull out) stroke. Which may or may not have a negative effect on the placement of pigment into the skin. But when the points close and the cycle begins to repeat, the magnetism needs to over-power the high spring tension all over again. And once again causing the armature bar assembly to violently move toward the full stroke position. And once again the needles will slam into the skin with more force than necessary.

It is this excessive needle force that creates the natural urge to move your hand faster than the needles can be removed from the skin. Thus causing the needle points to be dragged sideways while they’re still in the skin. And the force the needles penetrate into the skin increases when hand speed increases. It becomes a never ending cycle that causes poor quality and unpredictable results, and limits your artistic input.

The first duty of the front spring is to cushion the impact of the closing of the circuit. The front spring provides shock absorption, which in turn allows the momentum of the spring, armature and needle bar assembly to change directions smoothly, and more in time with the electrical magnetic circuit and stroke length.

When spring tension, stroke length, and magnetic force are balanced to the tension of the skin and effects desired. The kinetic energy in the moving armature assembly will push the needles into the skin to the proper depth. Being able to control the needle in this way allows you to use bigger groups of needles to get the desired effects with ease.

When you adjust the contact screw, you are actually creating a harmonic balance between the front and rear spring tension, the magnetic force, the reciprocating kinetic energy, size of needle group and skin tension.

The springs want to return the armature bar assembly to the springs’ natural (straight) position, at the same time magnetic force is pulling the armature bar assembly out of the springs’ natural alignment. The magnetic pull over powers the springs with enough force to motivate the armature bar assembly towards the full stroke position.

The magnetic force begins building as soon as the contact points close, and continues to build for a millisecond, or so, after they open. The magnetism continues to build until all electrical current that was allowed to pass through the points while they were closed, has passed entirely through the winding of the coils. When the last of the current has passed through the coil windings the magnetism instantly subsides, releasing the magnetic pull on the armature bar. The magnetic force depletes just after the armature bar begins to move, it happens very fast. At the instant the magnetic pull is released from the arm-bar, the kinetic energy in the armature bar assembly becomes the force that should actually be pushing the needles into skin. I say "should be' because most tattooers and machine manufacturers don't understand that high speed, short stroked machines, with stiffer than necessary springs don't allow this to happen.

With a short stroke or high spring tension, the needle penetration into the skin is stopped by the armature bar hitting the coil core, or the holding back the needles by the tattooer as they rake the skin with fast hand speed. (not a very accurate way of putting pigment into the skin)

The excess power that pushes the needles into the skin, of an “improperly” tuned short stroked fast acting machine comes from the magnetic force and the force generated by fast hand speed, not the kinetic energy. Pulling the armature bar to the full stroke position with the magnetic force makes it hard for the tattooer to control the actual force of the needles as they are applied to the skin. (when there’s too much magnetic force, you’ll tend to speed-up hand movement and hold back the needles, which is a conflict in the process of tattooing)

With a long stroke machine, with proper spring tension and proper voltage, the needle penetration is stopped by skin tension, and the knowledge of the machine operator. Knowing how to place the pigment is paramount to getting it there, in the right dose without skin damage. Being able to control the “power” of the machines stroke at the needle point is equally as important as knowing how deep to allow the needle points to penetrate into the skin.

The electromagnetic tattoo machine, when properly tuned, is such a precise instrument that no other Man-made device will ever replace it as a tattoo tool for Professionals. Because this machine provides the best method of putting pigment into the skin there is ever going to be, you as a tattoo artist, should learn to control and manipulate every little detail of the machines components, and their combined effects on the operation of the modern Tattool machine.

The following description of the wire wrapped around the coil core is the most precise information you’ll need to understand in order to understand how the kinetic energy comes into play, and why we should use it to push the needles into the skin.

What should be happening with a properly tuned machine is, at the second the circuit breaks (the points open or separate) the electricity to the coils is turned off. Even though the electric current is shut off at this instant, the magnetism does not stop that suddenly. It actually subsides at a rate determined by the voltage being applied, and the distance from the open contact point to the end of the coil windings.

The diameter of the coil core influences the operation of the machine in several ways. The biggest influence the diameter of the coil core has, is on the overall length of wire that wraps around the core. It is the total length of wire, commonly measured by the number of wraps around the coil core, that determines the rate the magnetic force dissipates when the circuit is opened (points separate).

The difference in the time it takes for the electrical current to pass all the way through the coil windings, is the difference between a 6 wrap coils compared to the length of wire around a set of 8 wrap coils, compared to the length of wire around a set of 10 wrap coils with the same size core. The more wire around the coil core, the longer the magnetism pulls on the arm-bar, the shorter the wire the sooner the magnetism depletes after the points separate.

In reality the magnetic force generated by 6 wrap coils is strong enough to tattoo with.

But the distance the current has to travel through the coil windings is so short, the magnetism subsides too fast after the point separate, and that makes the armature bar assembly move only a short distance before the magnetism comes to an abrupt stop.This fast buildup and depletion of the magnetic force prevents sufficient build up of kinetic energy in the arm-bar assembly to be a usable amount. It is the speed the magnetism builds and depletes that renders 6 wrap coils inefficient. (A short stroke compounds all problems associated with fast acting machines.)

On the other hand, the length of wire in 10 wrap coils is so much longer (comparatively speaking) that the coils stay magnetized a much longer period of time after the point separate. This extended time the armature bar is being pulled toward the coil post causes the needles to travel a longer distance, maybe the entire stroke length, under full magnetic power. Thus making the needles penetrate the skin with unnecessary force. The magnetic force of 10 wrap coils is not that much stronger than 6 or 8 wrap coils. But the slow release of magnetism actually causes you to increase your hand speed to compensate for the extended time the needles are moving under full power.

And this prevents the tattooer from having total control of the needle tips. The extended length of time the coils stay magnetically charged, makes 10 wrap coils too slow for best choice.

It just so happens to be, that 8 wrap coils are naturally our best choice. The amount of physical difference between 6, 8, and 10 wrap coils is not much. But when you look at the length of time that the point gap is open compared to closed, you can see that everything has to work very fast and very accurately.

In order for the magnetism to buildup, and then subside fast enough to be completely depleted by the time armature bar and needles have traveled the very short distance from fully retracted, to the exact point where the magnetic force is no longer pulling the arm-bar, and the kinetic energy becomes the driving source, the length of wire around the coil posts needs to be within a certain length, 8 wrap coils provide the right amount.

(If we were moving the needles at 80 strokes per second 6 wrap coils maybe the right speed. At 40 strokes per second 10 wrap coils maybe the right speed of coils. But approximately 50-60 strokes per second seem to be the natural stroke speed we work with. 8 wrap coils provide the power and timing that go along with the natural hand moment of most tattooers, and the skins natural ability to accept the pigment at that pace.)

The force of your needle (including hand speed) going into the skin should not be any stronger than is necessary to push the needle group being used to the right depth. It is the same principle as our spring theory in the sense that you should use only enough spring tension to pull the needle from the skin. You should use “just enough force” to push the pigment in the skin.

This is where the details make the difference. If the armature bar was ringing a door bell, it wouldn’t matter that the magnetic force was in full effect when the armature bar hit the bell and bounced off. The bell would just ring louder.

But with the skin taking the brunt end of the force, and with the goal here to make a needle tip penetrate the skin, a very small amount, 0.030 - 0.050 of an inch or so. And the fact that we can’t see how deep the needles actually penetrate into the skin. We need an alternative way to prevent the needles from penetrating to deep. In order to keep them from completely over-powering the skin and penetrating too deep, the motion of the needles needs to be able to respond to a very small amount of resistance from the skin. This is why it is so important that you understand that it is the kinetic energy that should be pushing the needles the right depth, not your hand speed or the magnetic force.

This is how it works. As soon as the points separate the electric current is cut off. By this time the arm-bar assembly has already begun moving toward the coils magnetic force. Even though the electricity has been shut off, the current that is already in the wire has to pass all the way through the coil windings before the magnetism subsides. It is during this very brief period of time, from the time that the points are closed until the current has passed all the way through the coils windings that the kinetic energy becomes strong enough, that as soon as the last of the electric current has passed the end of the coil windings and the magnetism is no longer in effect, the kinetic energy (armatures bars momentum) becomes the power that makes the final push of the needles into the skin. Because this kinetic energy is not very powerful and depletes very fast, the skin tension can become an influence on the place and pace the needles come to a stop. This happens right before the main spring tension over powers the momentum of the arm-bar assembly, and reverses the direction of the needles, pulling them from the skin.

The smaller the point gap, and/or the stiffer the front spring tension, the faster things happen and the harder it is to get what I’ve just described to happen. If the point gap is wide enough and the tension of the front spring is such that the spring can bend a little when the points close when the machine pulls the needles from the skin under normal operating conditions, the time the points are actually closed is longer than they are with a stiff spring. And the motion of the arm-bar assembly changes directions smoother, similar to the way the needles should change directions in the skin. When the springs are strong enough to do the job, but not so strong that they over power the skin, you can work vary fast (relatively speaking) with what ever size of needle group the techniques being applied require.

And this is where it should become easy to see, that when you have a stiff front spring, like one with an O-ring, the spring doesn’t bend like a softer spring does when the points close under operating conditions. A stiff spring causes the arm-bar assembly to change directions quicker than a soft spring does. And this causes the points to open quicker, which actually shortens the time the magnetic force pulls on the arm-bar, which shortens the amount of time the kinetic energy can build in the armature bar assembly. This shortening of the time the magnetism is allowed to build-up, requires higher voltage to get the arm-bar moving in such a short amount of time. And this is where front spring tension starts requiring more power to run the machine than it takes to push the needle to the right depth.

The difference between a stiff spring and a softer spring can be like night and day when it comes to the technical effects possible. Soft long strokes provide a wide range of technical effects that are not possible with short stroked machines. Just knowing this, actually gives your imagination (and income) room to grow.

When every thing related is timed right, magnetism is a very predictable, controllable and precise energy source of which the cycle rate doesn't slow down when the voltage is reduced, only the power of the magnetic force is reduced when the voltages is reduced. And this is why magnetism will never be replaced as the main power source for professional tattoo machines.

As a comparative example to the other most common power source; When the voltage to a rotary machine is reduced, the power and length of the stroke stays relatively the same. Only the speed of stroke is reduced. The power the needles hit the skin and the length of stroke remains the same, because the motor still has to make a full revolution to complete the stroke cycle. This type of stroke movement limits rotary machines to a very limited style of tattooing. You might master the rotary machine and the limited techniques possible, but you will never master tattooing through using one.

On the other hand, when the voltage to a properly tuned electromagnetic machine is reduced, the machines speed will stay relatively the same, while the length of stroke and the power of the stroke is reduced by control of the operator. Giving the control of depth and power of needle penetration to the operator, not the machine. And this gives you the power to place the needle points exactly where “you” want them.

You’ll know you don’t have enough voltage power, or the stroke is too short if you feel that you have to “push” the needles into the skin, or rake the skin many times before saturation occurs. If your stroke is correct, turn up the power a little at a time until you don’t have the urge to push the needles into the skin, or rake the skin many times to get the needles to leave the right kind of mark.
If your stroke is too short, lengthen the stroke a few thousands of an inch at a time, and try again, and do this until you get the machine to leave the needle mark you want. Once the machine is properly tuned it should do all of the work, you should only have to drive.

It is the total resistance of all electrical components, and the mechanical tension and friction, this includes spring tension and needle friction in the tube tip, including the skin tension, that determines the voltage necessary (at the time) to push the needles to the proper depth in the skin for the effects desired.You’ll know when your spring tension is too much, or the friction at the tube tip is too great when the machine won’t run with less power than you can tattoo with. Even though your clients skin is the least influential component concerning the mechanical and electrical system, it is the single most important component in the fine art of tattooing, and desperately needs to be understood as such.

Regardless of the actual spring tension, if the main spring tension and the power that pushes the needles into the skin is not balanced to the skin tension, the needles will impact the skin much harder, (or softer) than necessary, possibly damaging the skin while depositing the pigment into the in the wrong area. Not enough needle force or penetration depth causes many scaring and healing problems. Tattooing an area a second time with the same short stroke set-up only makes things worse. With a mis-tuned machine you can easily find that you have developed a technique of chasing a problem you’ll never catch up to. And that is the probability of scarring the first few layers of skin cells of the dermis.

When changing the power(voltage) on a electromagnetic machine the impact force of the needles change, but the speed the needles are moving does not change more than approximately 10%. Which is only a slight change in the speed of the machine. It doesn't take much increase in voltage to greatly increases the power at which the needles impact the skin. A machine that is running too hard will cause the tattooer to inadvertently increase their hand speed.

And high hand speed causes the needles to drag through the skin. Dragging the needles side ways through the skin, while the needles are working the skin, causes sever skin damage. Resulting in under saturated pigment, scaring, and slow healing times, and may cause the pigment to appear to be faded or blown-out, or not to be there at all when the tattoo is healed.

High hand speed makes the tattoo process less controllable and causes most of the pain sensation experienced while being tattooed. It is this jerky hand motion that prevents, or at least makes it very difficult for the pigment to be feathered into the skin for a smooth transition of solid pigment to a transparent special effect. If you’re have trouble feathering in pigment, slow your hand speed down and lengthen your stroke.

When hand speed is fast enough to accommodate the, too fast and too powerful machine, holidays and overdose spots are created. High hand speed and the over powered machine also prevents the tattooer from reworking, or smoothing out the uneven pigment saturation, without the risk of over tattooing the skin.

When hand speed and the penetration rate is slowed to a more controllable rate, pigment saturation occurs quicker, easier, and special effects are easier to achieve. Healing time and discomfort (pain) is also reduced. Slow hand speed and low needle impact power allows for larger needle groupings to be used with great results and a wider range of special effects. Large needle groupings also provide better saturation, and smoother coverage. Slow hand speed allows time for the needles to deposit pigment into the skin in the amount determined by the tattooer.

Controlling spring tension is paramount to becoming a Master Tattoo Artist. The best method for adjusting spring tension on a k model machine is to start with adjusting the swivel head screw until the right stroke length is acquired, then
compress both springs by extending the point screw 1/2 a revolution at a time until the right spring tension occurs. Then reset the stroke length to the desired stroke length.
This tune up and spring tension procedure is good for all electromagnetic machines, but most easily applies to The K-Model machine Manufactured by Original TATTOOLS

Kelly Miller
Editor in Chief - Tattoo Artist
Published December 1, 2010