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Machine bog is when your tattoo machine slows down or bogs when the needles enter the skin. On coil machines the bog actually reduces penetration in to the skin. This bog is a good thing, it is important for a machine to respond to the resistance of the skin. On a coil machine it helps with blowouts and beating up and overworking the skin. On a rotary the function is similar but also has a different purpose. Before we get in to that lets talk about machine speed a little bit.

Machine speed is usually represented in cps, or cycles per second. That is the frequency with which the needles make a full stroke. The speed of the machine is often used to describe a machine and artists are relatively familiar with the term and concept. Liners run faster than shaders, etc. So machine bog is actually slowing the machine speed. When the machine comes under load, it responds to that load pushing against it slowing the mechanism as a result. This is all true but we need to look closer than this superficial level to understand why that bog is so important.

You can’t simply look at machine speed as the time it takes the mechanism to make a full rotation, tattoo machines are so much more dynamic than that. You must also consider the speed of the down stroke, the speed of the up stroke and their relation to each other. In coil machines the mechanism to create the downstroke is different than the mechanism that creates the up stroke. The down stroke is caused by an electromagnet and the up stroke is caused by a spring. That is different than a rotary machine because the downstroke and the up stroke are both created by the motor. The coil machine mechanism is so effective because you can essentially tune the down stroke and up stroke separately. You see in a tattoo machine the goal isn’t to have a machine that comes down as fast as it retracts, that causes low saturation and high trauma. The goal of machine builders has always been to create a stroke that comes down quickly to penetrate the skin and retract more slowly so that ink can be efficiently deposited in to the skin, this movement also pushes the ink down to the skin where it creates a pool around the needles on the skin. When this relation between down stroke and up stroke are altered you can get turbulence in the ink well which pushes the ink away from the needles, and worse yet a negative flow where ink is directed back up your tube.

On rotary machines builders that truly understand the process of tattooing find ways to manipulate that up and down stroke of the machine because it’s natural tendency is to be consistent down and up. I say machine builders because there are many tattoo machines and products on the market designed by engineers that just don’t know anything about the nuances in tattooing. I’ve had lengthy conversations with some of these people and trust me, the limited knowledge they have of the process would scare you. They’re employed to design a mechanism that makes a needle go up and down, that’s it. Well a tattoo machine needs to be more than that. So how does a machine builder design a rotary machine that has a faster downstroke and a slower up stroke? The answer is by manipulating the geometry of the machine and pairing it with a motor specifically chosen to respond to load in a particular way, at a particular speed window, at a particular force. DC motors are not all created equally. Each one has different specs that make them ideal for different purposes. You see bog only happens when the machine is under load or under resistance. There is no load on the downstroke until the needles reach the skin, so the needles speed down to the skin where the mechanism is designed to respond to that load, by slowing down. So in a sense we are robbing from that down stroke to give to the up stroke. So the needles spend a little more time in the skin and you still get a snappy down stroke. As a machine builder you don’t want the machine to bog too much or it will stall, which is bad. Bog too little and the needles speed out of the skin as fast as they go in not depositing ink efficiently and creating unnecessary trauma.

As a machine builder I’m always surprised when machines are marketed as not bogging down. That all this money and engineering was put in to creating this device, and no thought was given to why. It’s the equivalent of a beautiful handmade guitar that you just can’t tune. You could learn how to play it but it’s not gonna make it easy for you.

I guess that’s just my 2 cents for what it’s worth. I think it’s important to educate the industry and allow them to make educated decisions. Tattooing is a goldmine right now, lots of outside companies are dumping money and products simply marketing a brand, a label or just a shiny pretty machine with lots of features just trying to get a piece of it. It’s good for consumers to ask the question “Is it better, or just different”? And it wouldn’t hurt to ask the question “What does this engineer know about doing a a good tattoo?,” either.

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