Coil Tattoo Machines 101

A Workhorse Irons Bulldog frame.

 I've been working on this blog for a little while now, mainly because I am about to share a very unpopular opinion in the tattoo community.  If you know what to look for, you can get quality a tattoo machine from a no-name, off-brand, or foreign manufacturer, and often save yourself hundreds of dollars.  The idea that you have to spend hundreds to get a good tattoo machine is promoted by tattoo studios for a variety of reasons, mainly in the hopes that they will keep tattoo machines out of the hands of untrained professionals.  If you take a look on Craigslist.org, you will see that the misinformation campaign is not working.  In fact, it has many professionally trained artists believing the propoganda and putting all their faith in the amount of money they spent being a guarantee of quality in the devices they buy.

 "You get what you pay for" is a popular anecdote about tattoos, and in most cases it is true.  Quality comes at a price, and if you are not willing to pay then there is a good chance you will not get quality.  However, we also all know that some artists are over-priced, charging more than their workmanship is worth or charging more than what a more talented artist might charge without the hype of a "celebrity" name attached.  It is no different with tattoo machines, and in reality those who malign tattoo machines from sources they consider unprofessional often own machines that are composed of components manufactured by those same overseas companies producing low-priced tattoo machines.

 That said, you have to know what you are looking for.  When ordering tattoo machines on-line, you are buying sight-unseen.  You won't know what you have until the machine arrives.  While the price-point is no guarantee of quality, a higher price does at least suggest higher quality materials and more precise manufacturing.  While I would argue against needing a $300+ tattoo machine to do a good tattoo, I would also look to a $25 machine as being the source of many problems a tattoo artist might have in executing a tattoo.  My $300 machines, purchased simply because I wanted them, tattoo no better than my $100 machines.

 If you don't know what you are looking for in a machine, you will always have problems with your tattoo that you simply cannot explain.  A solid apprenticeship should teach everything you need to know about a tattoo machine, but just like tattoos and tattoo machines, quality in an apprenticeship is not always a given.

 What I am offering here is just some basics.  You have to have some experience with a tattoo machine for most of this to be relevant.  Hopefully this will augment some of the things you are already learning.  Also, most opinions on tattoo machines are just that, opinions.  They are based on some science but mostly the experience of the individual artists.  Great tattoo artists have never been afraid to experiment with their machines; trying out different materials and configurations.  Most the information I offer here suggests tendencies in machine form and function.  Ultimately, the artists determines what type of machine works best for them based on what they are trying to accomplish.

 The ideal machine runs consistently with minimal adjustment.  It does what it is expected to do.  When an artist can rely on the machine to operate in a particular manner, and understands how that operation will effect the stroke the machine makes, he or she can be more confident in using that machine to execute a tattoo.  Cheap materials, poor manufacturing standards, and unnecessary adjustable components rob a tattoo machine of its consistency.

 Frames

 If a better tattoo can be expected from a better tattoo machine, then a better tattoo machine can be expected from a better tattoo machine frame.  There is much ado about frame materials; brass, iron, steel, zinc, aluminum, and even more exotic materials all have their own strengths and weaknesses.  Heavy materials, like brass or iron, tend to reduce vibration.  Lighter materials, like aluminum or zinc, tend to allow the tattoo artist to work longer (as holding a vibrating hunk of metal above your hand for hours at a time can be a struggle).  Conductive materals can have the coils make direct contact with the frame base, while non-conductive materials require a yoke to form the u-magnet with the coils.  If your frame heats up, there is typically a problem with the circuit and not the frame.  The magnetic-field of a frame has so little effect on the operation that other aspects of the machine overcome any concerns about the materials effecting the magnetism of the machine (although some materials can become magnetized themselves).

 The main concern about a tattoo machine frame is it's geometry.  This includes the machines frame base length (a longer machine tends to operate slower and lends itself to shading or coloring) and post-height (which makes room for different length coil-cores).  The most important aspect of frame geometry, however, is the alignment of the spring mount, the frame base, and the tube vice, or more precisely, the screw-holes and opening of the vice.

Two cheap frames, but the frame on the left was less expensive yet has far better alignment than the frame on the right.

 If the frame is out of alignment, there will always be issues with its operation.  Being out of alignment can cause the frame to heat faster during operation and can wear out springs faster.  The pull on the armature bar will typically be inconsistent since it is not aligned on the center of the coil cores.  The picture above shows two relatively inexpensive machine frames, but the alignment of the one of the right is so far off the center of the frame base and the spring mount is completely out of line with the coils and tube vice that it is essentially worthless.  You could tattoo with it, but you will more than likely run into problems in the quality of your work that would be less likely with frame on the left.

Note the cut-back post option.

 Front upright alignment effects the operation of the machine making it better for a particular function; running faster or running slower.  The front upright is typically either aligned with the front coil, or forward of the front coil.  The further forward the front upright, the larger the machine stroke and the slower the machine speed.  Frames designed for lining tend to keep the front upright close to or in alignment with the front coil, while frames designed for shading or coloring tend to be forward of the front coil.

 Cut-back frames allow for the position of the front binding post to be adjusted; meaning the frame can be configured as a lining or shading machine, depending on the post's position.  While this can be advantageous in some situations. most professional tattoo artists use several machines each configured for different function.  Cut-back frames have one more point where things can come loose and move with the vibration of the machine.  

Note the slight pitch of the spring mount on the right.

 A final aspect of frame geometry to consider is the pitch of the spring mount.  Generally, a spring mount should be flat or parallel to the frame base.  A mount that has a pitch can offer greater tension on the back spring, resulting in faster machine operation.  Some frames have even been designed that allow the pitch of the spring mount to be adjusted (which is again, one more moving part to vibrate loose).  The artificial tension on the back spring will make a machine tend to operate as a liner, but at the cost of greater wear on the spring itself.  

 Frames are typically produced in one of three ways; cast, wire-cut, and pressed-then-bent.  Frames which are cast are typically considered ideal; the metal for the frame is poured into a mold resulting in one solid and (hopefully) consistently stable piece.  Wire-cut frames essentially take a solid piece of metal and carve a shape out of the block.  The result is still a solid piece of metal (hopefully), with clean angles and lines.  This is common to machines that are massed produced overseas.  Equally as common are the press-then-bent machines.  These are less desirable because the process of bending the metal into shape creates inherent weak-points in the frame, and unless the cut was designed to take into account the final shape there may be alignment issues from the bending process.

 Frames to generally be avoided are frames that come in more than one piece.  Tattoo machines vibrate, which is why you want your frame to be as solid as possible  With a frame that is several pieces bolted together, the vibration loosens the parts which means changes in the machine's consistency and the need for constant re-adjustment.  The vibration of a tattoo machine can change the alignment over-time of a frame that was pressed-then-bent into shape, a wire-cut frame that is too thin, or a cast frame that is flawed or cheaply produced, but frames that are multiple pieces suffer from this draw-back more than others.

 Keep in mind that, except for the alignment, other aspects of the frame can be overcome by changing the other components of the machine to compensate.  For example, a longer frame can be sped up using higher guage springs or a small capacitor (among other methods).  Again, these aspects of machine design indicate tendencies, and it is up to the artist to determine what works best for them.

 Coils

 Coils generally come in 8, 10, or 12 "wraps" (layer of wire wrapped around the core) of 24 AWG red or green magnetic wire with a 150c heat rating).  The wire is wrapped around typically a 3/16 or 5/8 iron core or bobbin core.  The number of wraps effects both the speed of the machine (slightly) and the downward pull of the electromagnet formed by the coils.  Greater downward force tends to be favored in machines used for lining or coloring. 

 Ideally, coils have a consistent wrap.  That means no gaps between the wire as it goes around the core.  This is more easilly achieved with a machine than by hand (as one who has wrapped coils, I can attest to this fact), however when buying coils mass-produced you are again leaving yourself subject to the manufacturing process and quality controls of the producer.  Coils typically come wrapped in an insulator or sleeve that is opaque or features art of some kind.  Even with a transperent insulator, you would only be able to see the top wrap which could hide flaws in the lower layers.

 Moreover, some unscrupulous manufacturers pad their coils by adding additional insulator to the wrap, making the coils appear to have more wraps than are actually present.  Without cutting the coil open and unwinding it, the things to look for are smooth, straight insulator sleeves and to compare the coil-performance in a machine against what you would expect.  If the coils have a bloated appearance, that is an indicator that the wrap has been padded and your are getting a smaller wrap than indicated.

 Tattoo atists who buy machines from off-brand manufacturers almost always change the coils with sets they have purchased from a trusted source.  Even with reliable manufacturers, mass production can often result in flaws that would prevent consistent operation.  My experience has been about 50/50 with low-priced machines; they are equally likely to come with good coils as they are with bad.

 Capacitors

 The capacitor, along with the wire, solder lugs, and coils (in contact with a conductive frame or yoke), form the electro-magnet that drives the function of a tattoo machine.  The purpose of the capacitor is to regulate the "flow" of electricity through the circuit, making the machine more consistent.  47 uF (units of Farad) and 22 uF are the most common size capacitor used on all machines, but adjusting the capacitor size can change the way the machine operates.

 By increasing the uF, your larger capacitor will slow the circuit down, and may also increase the downward force.  A smaller capacitor is faster and has less force, typically.  Keep in mind that other factors may off-set the machine's function (force is more a function of the springs).  The second most usual culprit in a machine over heating is a bad capacitor, with the first most usual culprit being an untrained artist who thinks increasing the voltage on the power supply will increase the machine's power and speed.  Mechanically, the machine has an upper performance limit.  The voltage limit (v) is generally printed on the capacitor along with its uF rating.  Exceeding that limit can damage your capacitor and cause your machine to get hot (as well as burn/bore a hole through your front spring in extreme cases).  Most capacitors used have voltage ratings of 25 or greater, while machines are typically run at 12 volts or less.

 Tattoo machine circuits are typically sold as a single unit.  Capacitors tend not to last as long as coils.  A simple modification to the circuit can seperate the capacitor from the coils by putting the capacitor on its own line with seperate solder lugs.  This allows the capacitor to be changed out from the coils if an issue becomes apparent or if you simply want to try a different sized capacitor on your machine.

 Springs and Armature Bars

 The spring and armature bar assembly is the moving part of the machine.  When the electric circuit of the machine is closed (the front spring is in contact with the timing screw), the coils form an electro-magnet that pulls the armature bar downward toward the coil cores.  This opens the circuit, shutting off the magnet and releasing the armature bar.  The tension created by the downward motion of the assemby on the back spring is reversed, and the assemply moves upward until is makes contact with the timing screw, and the cycle repeats.  The cycle speed of a machine helps determine what it is used for.  Lining machines tend to run faster, like 120-140 (or more) cycles per second, shading machines tend to run from 110-120 cycles per second, and coloring machines tend to run 100-110 cycles per second (or less).

Armature Bar/Spring Assembly

 It should be noted that we are again talking about tendencies, not hard rules.  The use of a machine is determined by a combination of factors and how the tattoo artist tattoos.  There is no right or wrong speed.  A faster machine requires a faster hand.

 Armature bars are typically made of iron or another metal that is ferromagnetic (reacts to magnets).  Springs are usually made of (gasp!) spring steel.  Spring steel is an alloy that allows the metal to return to (or snap-back to) its original shape when it is bent or twisted. Armature bars come in different weights and lengths, with heavier a-bars helping to slow the machine's speed.  Springs come in different gauges; thicker gauges speed the machine up and increase the downward force of the assembly.

 A front spring is bent at about 15-25 degrees.  The greater the bend or "roll", the softer the force of the machine stroke (as the needle has a shorter distance to travel).  The gauge of the front spring (also referred to as the timing spring) impacts the speed of the machine; a thicker gauge results in a faster machine because it has less "give" when making contact with the timing screw than a thinner gauge.  Back springs are generally flat, and determine the tension of the machine and the assemby's downward force; greater the gauge the more force applied.  Lining machines, color machines, and large needle groups generally require more force than shading machines or small needle groups.  Tension can also be increased by slightly bending the back spring.

 Traditionally, springs have come in two pieces; front and back.  When I first purchased a machine with a one-piece spring, my thought was that the manufacturer was cutting corners.  One piece means a few less steps in the fabrication process and would be less expensive.  However, I have seen several reputable companies offering one-piece springs.  The advantage I could see from a one-piece spring is that the spring is in contact with the armature bar until the point where it is bent, making it potentially more stable.  The standard spring assemply leaves the front spring elevated by the back spring slightly above the armature bar.  The disadvantages include the point where the spring is attached to the armature bar being the tension point and weaker than the standard assembly.  With the standard assembly the point of tension is the center of the back spring.  It also offers less flexibility in customization; the one-piece spring is a single gauge throughout, while the tradional two-piece assembly allows for two different gauges depending on the artist's preference.

 Another innovation that I am more in favor of is the "Tru-Spring" system by Eikon.  Armature bars in this system are cut with a 15 degree angle and a seperate mount for both springs.  This means there is no bend in the front spring, therefore no weak-point in the spring.  Your spring potentially lasts longer than the traditional bent spring, but it also means that you have to buy your springs from Eikon or cut them yourself in order to have replacements.

 You may notice that I did not include an o-ring in my assembly.  It is my opinion that consistent operation should be the goal when assembling a tattoo machine, and that an o-ring reduces that consistency.  The o-ring can quiet the noise of the machine, as well as speeding up the machine by adding tension to the front spring.  This can be compensated for by making other adjustments if it is not desired.  However, since the o-ring is made of rubber, it breaks down faster and changes shape as the machine is used, changing the way it impacts the machine.  O-rings, like gommets, should be thrown away after each tattoo, but many artists fail to do so.

 When attaching the armature bar/spring assembly to the spring mount on the frame, there are a few points to be aware of.  You want the a-bar and springs to align down the center of your frame base, which should be aligned with your tube vice.  An alignment tool helps ensure your springs are aligned on your armature bar.  The armature bar jig is placed in the tube vice, with the armature bar pin sitting in the jig-slot, lining the bar up with the center of the tube-vice.  This should also be directly over the center of your coil cores on a frame with good geometry.

 The next point(s) of concern is the space, or gap, between the armature bar and other points on the machine.  Much of this article has discussed speeds and measurements that require a metered power supply to varify.  Without a supply that tells you the Cycles Per Second or Hertz (hz), duty cycle, etc, you will have to rely on visual adjustments and the sound of the machine.  The armature bar should flutter between the coils and the timing screw.  The noise a machine makes should be a consistent, smooth sounding buzz, with no "clacking" (which suggests the movement of the a-bar is incorrect.  

 There are three gaps to check; the point gap, the air gap, and the back coil gap.  The point gap is the space between the front spring and the point of the timing screw when the armature bar is depressed.  The wider the gap, the slower the machine will run.  The timing screw can be adjusted while the machine is running, allowing for you to check the machine visiually and by sound, or to see what the machine is doing on a metered power supply.  

 The air gap is the distance between the bottom of the armature bar and the top of the front coil core.  This gap determines the throw of the needle, or how far downward the needle will travel.  The air gap is impacted by the point gap, and vice versa, so a faster machine will have a shorter airgap and potentially less throw then a slower machine.  This can be compensated for by adjusting the tube in the tube vice and setting the depth of the needle visually.  The less throw a machine has, the fewer needles it can push.    

 The back spring gap is the space between the bottom of the armature bar and the top of the back coil core.  When the armature bar is depressed, the bar should touch the front coil core, but there should be a slight space between the back coil core and the armature bar.  If the armature bar touches the back coil, there is not enough room to allow for proper movement.  Too much space puts unnecessary tension on the back spring, which can snap.  Ideally, this space should be about the same thickness as a sheet of paper.   

 When buying a tattoo machine, these are all points to consider; frame geometry, material, and type, coil quality and size, hardware materials (binding posts, timing screw, armature bar, screws).  Machines purchased from a manufacturer almost always require some adjustment before use, if only to tune the machine to the preference of the artist.  When buying machines, it is worth while to also invest in additional spring sets, different weighted armature bars, other hardware, and coils so that if a part of a machine that is purchased does not meet your expectations it can be replaced.  If you know what you are doing, you can purchase an average machine and make it great for far less than purchasing an expensive machine and hoping it lives up to the hype around it.  While the information offered here should be of some help, there is still a great deal of information about machine assembly and adjustment to be discovered through a proper apprenticeship. 

 Jason Sorrell is a writer, tattoo artist, satirist, artist, and generally nice guy living in Austin, TX.  He loves answering questions about tattoos.  Shoot him a message at https://www.facebook.com/tattoonerdz/