Rotary Tattoo Machines

The following is a conversation I had with an artist via e-mail where we discussed many of the questions that I'm frequently asked. i asked for permission to post it here to be resource for others looking for the same answers. Please enjoy!

Hello joshua
Im a tattoo artist in France, I’ve been tattooing for 5 years and
I've always worked with coils. I've only tried a rotary neotat and a Hawk Thunder machines for a time but I dont like it, the machines dont have force to penetrate solid ,i miss the slap of coils.
I read aaron cain said that rotaries aren’t good for solid work.
I am a little confused. I see some tattooists that I like use your machines and your work looks solid, as you make both coils and rotarys can you tell your opinion please?
I like to buy one of your rotarys but im afraid that they don’t have force
Sorry my english

 

JB- In my opinion rotaries don't have the slap per say of a coil but they are more powerful. It's all about the stroke. Coil stroke starts off strong and then weakens as the needles move down. Which gives it that "snap" that your referring to. Rotaries carry the same force and roughly the same speed all the way through the stroke. Which makes it more powerful. Saturation is obtained by the ability to hang the needles in the skin just a touch longer so your hand movement opens up the skin a little bit more to deposit more ink with less holes. You have more ability to do this with rotaries because you have full control of needle speed, where with a coil your only controlling speed as a function of force, but mostly just adjusting force. 

So a rotary will feel less forceful than a coil when ran properly but is much more efficient. It should be avoided to turn the rotary up so far as to get the same hand feel as the coils your used to running. If you run a rotary too fast and too hard it won't open the skin at all and will just cause a lot of trauma.

 

S- Thank you so much for your help joshua
So maybe I guess that my mistake is that I always try to feel a rotary as a coil.
As you said we shouldn’t run a rotary so fast as a coil ,so we need a rotary with a motor with a very good torque,yes?
Because to get force in a rotary we need put more voltage,and more voltage/more speed
What the stroke you have in your machines is 4mm?
The neotat I try have 4.2mm

 

JB-  Every motor is different. One mistake that people make is thinking that a 4mm cam is going to react the same way on another machine as it did on the last. Every machine is built and designed differently, different motor, different offset and different frame geometry, etc. You don't need a lot of torque you just need the right amount of torque at the right speed. If the machine is too torquey at lower speeds then it will have too much torque at operating speeds and tear up the skin. If it doesn't have enough torque you will have to turn it up too much to get the torque you need to penetrate the skin, that increases the speed causing the machine to run too fast and will tear up the skin. 

There's no magic formula that works for every machine. I tune my machines to be ideal machines for tattooing because I understand tattooing, I'm less concerned with simply making a mechanism that makes a needle go up and down. Most rotaries on the market are just that, mechanisms that make a needle go up and down. By using the frame geometry, the cam offset as a lever and a couple other tricks I’ve developed I can create a stroke in the machine that slows down and responds to the skin at just the right spot in the machine stroke. This is how I tune my rotaries. 

 

S-  And about a direct drive rotary(circular movement) and a rotary with an up down movement ? Of course that depends of the machine. But some people defend that a direct rotary machine is better for solid tattoo, because the other rotaries with an up/down movement the needle spends more time in the down movement.
You agree?

 

JB-  I don't like direct drives unless your stippling with them or running cartridges.

 

S-  Sorry but,why is best for cartridges? Is a direct drive more powerful?

 

JB-  Because a direct drive can't really be tuned. There's no mechanism for modifying the stroke characteristic besides adding weight to the spindle mass, but this rarely offers any benefit to making a tattoo machine better at tattooing, it usually just adds a bit of force to the initial contact with the skin and then slows the movement down from there. Direct drives also cause a wobble in your needles since they have no mechanism for making rotational movement into linear movement. So the needles move side to side often times causing friction and rubbing on the sides of the tube. The use of cartridges with this system solves those potential problems.

These are questions a lot of people have, I would like to post this conversation to my website blog if that's ok, it would help answer a lot of questions for people.

Rotary tattoo machine stroke characteristics

I've been asked countless times what the stroke length is on my machines, if I can do custom strokes for someone who currently uses a 3.5mm and loves it and ultimately, why I don't do custom stroke lengths on my machines. In short, the stroke length on my machines are right about 4.5mm, I don't manipulate this because it is directly responsible for the tune and stroke characteristics that I've designed into my machines. Let me explain.

 Many people are mistaken that a shorter cam offset on a rotary makes for a faster machine. For example a 3-3.5mm stroke is meant for lining and anything above that is meant for shading. Because liners traditionally run faster than shaders, when not aware of the actual dynamics of the mechanism that logic may make sense. A smaller cam offset does not make the machine cycle faster however. The cam is not a gear, in that one rotation of the spindle will always equal one rotation of the cam, which will in turn one full stroke of the needle. So a machine that has a 3mm stroke running at 6v’s for instance will be running the same speed as the same machine with a 4mm stroke at the same voltage. That being said, cam offset does manipulate needle speed. This may seem confusing at first but think of it this way. A machine that is set up with a 4mm stroke running at the same voltage/ speed as a machine that is set up with a 3mm stroke the needle is cycling at the same speed as the 3mm, but traveling a greater distance in the same amount of time. So the needles are traveling faster but the machine is not cycling faster. This needle speed creates a snappy, punchy feel to the machine. A characteristic I like in my liners, and not as much in my shaders. In the same respects, a 3.5mm stroke will feel completely different on different machines. If you love your 3.5mm on your Neotat you wouldn't necessarily love a 3.5mm on my machines, There are too many factors to account for to make this generalization.

To break down stroke characteristics even further lets discuss responsiveness. Take into account that the cam is essentially a lever. The longer the lever extends from the center the harder the machine will have to work to move it against resistance. So a motor with a 3.5mm cam won’t be working as hard pushing a needle in to the skin as a machine with a 4mm cam. A DC motor unlike a coil machine however will always finish it’s stroke. Meaning it will always either go all the way around to complete a cycle or stall completely. A coil machine doesn’t have to finish a stroke. The magnets pull down on the armature bar, the needles engage the skin, when the resistance gets too great the downward motion stops and the springs pull the armature bar back up. When a coil machine is tuned and ran properly in the skin the armature bar won’t even reach the front coil on it’s cycle. The machine is being responsive to the skin, or the skin is telling the needles how deep to go, rather than vice versa. This is paramount in a well tuned machine, whether coil or rotary. This stroke characteristic allows the absolute most skin saturation, the least skin trauma and the fastest heal times. I use the coil machine example to describe a stroke characteristic that many rotary machine builders try to replicate with adjustable give. The way I allow for this with my machines is by pairing the ideal cam offset to the right motor. Every DC motor has a set torque rating at a set voltage/ speed. By pairing just the right offset cam to the right motor I manipulate the motor to slow down when meeting the resistance of the skin. By allowing the needles to slow down in the skin you allow the needles to open up the skin more. This allows for greater saturation, and a more efficient stroke with shading and lining. So without any adjustments, the machine is already set up and tuned to respond to the skin and to have the best stroke characteristics. Rotaries with a shorter cam offset often spend just as much time out of the skin as in the skin. This 50/50 stroke creates turbulence in the ink well of your tube rather than creating a nice flow of ink down to the skin.

The last topic I will discuss here is needle setup. So many artists I’ve talked to set up their machines how they were taught to do so by their mentors. A slight bend in the needle bar and adjust the tube tip to be even with the needle tip when the needles are fully retracted. This is absurd to use this as the rule of thumb for every machine you set up. Let me explain. If a machine only has a 3 or 3.5mm throw then this makes more sense, but I’ve seen so many people use this setup on a 4.5 - 4.6mm stroke machine. I only hang out the amount of needle I plan on using, I don’t care where the needles are in relation to the tube tip when retracted. Let me break this down. The further the needles are reaching out from the tube tip the further the ink has to travel to reach the skin, and the harder it is create a positive ink flow. This is even made worse when you consider that in this needle setup the solder band on the needle grouping never travels outside the tube tip, all but blocking ink flow completely. I like a longer stroke on my machines, not just because of the tuning it allows but because I can set up the tube to reveal as much needle as I want and the rest of the stroke travels in to the ink reservoir of the tube, and back out again picking up all that ink on it’s way down, creating a positive ink flow down to the skin. 

 

I hope this information is helpful, useful or at the very least inspires a new perspective when thinking about tattoo machines, more specifically rotary tattoo machines.