Wednesday, 30 July 2014

Homemade rotary tattoo gun from salvaged parts

Andrea has spent the last few weeks perfecting his homebrew tattoo gun, made from parts salvaged from most of the kind of equipment found around the hackspace. In particular, he found a simple servo-motor (from a large all-in-one printer/copier) and stripped off the encoder disk (sorry, CNC Paul, just didn't think to ask if it'd be any use to you!) and built a laser-cut frame around it.

The first design was made almost entirely "by-eye" and just happened to fit the components that made up the rest of the gun. After being dropped on the floor a couple of times, the flaws and weak points in the design soon became apparent, so a bigger, better, fancier design was put together.

The new design is not only made from super-awesome edge-light acrylic, and engraved with a cool retro-looking tattoo pattern itself, but extra bulk has been added around potential weak points.

The two pieces of acrylic are held together using M3 nuts and bolts. It's important that the nuts don't crush the acrylic, but maintain a nice, firm grip on it. So each bolt has no less than three nuts - one behind the head of the bolt, then another as a "spacer" and the third holds the acrylic tight up to the spacer bolt.

Using this arrangement, the nuts can be done up quite tightly, to grip the acrylic, without fear of the extra stress on the plastic causing it to bend and shatter under strain.
The handle (or grip) holding the needle is disposable, so a collar with grub-screw is used to attach this to the gun. And a simple rubber band applies enough pressure onto the needle to stop it flopping around as the rotary attachment drives it up and down, but without restricting its movement vertically.

The actual rotary head is an aluminium pulley, modified by adding an M3 bolt, slightly off-centre. The head of the tattoo-ing needle is connected to this, and as the motor spins, it causes the off-centre cam to drive the needle up and down, inside the grip.

Here's a video of the gun in action. Compared to the noisy clatter-clatter of a coil-based gun, this one is incredibly quiet.

The final result is quite impressive.

In operation, Andrea said that there was very little vibration compared to a coil-based gun. It's obviously much, much quieter, and there's also very little "splatter" while drawing lines. The lines are very precise and - apparently - "skin burn" is much less than when using a coil-gun.

The gun is also pretty handy at shading too. Using just a single colour ink, it takes a pretty decent gun to be able to create like a greyscale shading effect. Something which the rotary-junk-gun handled well too:

The crescent moon in this photo was completed in just a few minutes but proved, as a simple test, that the gun performs well as both a "liner" and a "shader".

Unsurprisingly, Andrea is quite pleased with the great performance from such a simple device - made relatively cheaply from a few parts lying around, that would otherwise have been confined to the tip.
Look out for more progress reports (and more members of the Nerd Club sporting new tattoos) in the coming weeks and months!