A while back, my cousin Cammie got a cool mechanical heart tattooed on her shoulder blade. Several months after, I had the idea of making a tangible replica of it. When Christmas came around, I had presents for her siblings, but not her, so I thought, “Hey, why don’t I build that heart now?” It only took about 2 weeks of work, on and off.
So here’s the tattoo.
I wanted to capture the tattoo in the highest level of entirety that I could. So breaking it down into components, we’ve got: 3 gears, an exhaust pipe, a hook to hang from, and what could be interpreted as a switch/button in the top-right. Simple enough right?
Difficulty: Easy to Moderate
Time: 2 weeks, maybe ~15 hours total
- Drill press
- Soldering iron
- Hot glue gun
- Wire cutters
- Wood stain
- Carving tools
- Copper tubing
- 2x AA battery holder
- DC motor
- 2-position switch
- Dremel Hand-tool
I didn’t take too many in-progress pics (as unfortunately usual). I wasn’t expecting this to be something I’d document and post, but it was a pretty well-received present so I figured I’d show it off.
I had originally found the wooden pine heart randomly at Joanne’s Fabrics, leading me to think of the idea in the first place. Pine was a terrible wood for this project; it’s way too soft.
Also, luckily, I found 3 perfectly sized gears at work and they just happened to have the same toothing! Even luckily-er, I had a geared DC motor of my own from a previously disassembled project. After taking the motor out of the gear housing, I found its toothing matched the gears!
Awesome, so I had my main materials: Pine heart base, 3 matching gears and a matching motor to drive them.
The rest of the materials I either already had, took from work (Sorry!), or bought at Home Depot. These included: a 2x AA battery holder, 2-position switch, copper tubing, brass hanger, gold chain, key, miscellaneous screws and washers.
At first thought, I considered this a 1-night or weekend build at most. I was wrong. Not entirely because of the amount of work, but because I messed up a bunch early on.
As I said, pine is soft. Way too soft to hold gears in place perfectly stably. So my first wooden heart, I drilled and carved by hand, leading to angled screw holds, and overlapping holes. Not good.
The straightness of the mounting holes for the gears was essential to having them spin freely. The slightest tilt saw the gears rubbing against their wooden base, causing too much friction for the small motor to drive them. Weak. I bought 2 more hearts, and messed up the second by using my hand drill again. I’d need a drill press for this. Back to work.
Bringing the project into work afforded me the use of a drill press and our dremel. I drilled out the 3 holes for the gears, and dremeled out the cavity for the motor. Easy-peasy. Must invest in dremel.
In addition to straight mounting holes, adding washes to the gears made a huge difference in their spin-ability. Much less friction made the motor’s job a LOT easier. Finding the perfect tightness of the mounting screws took some finesse, but ultimately determined how well the gears would spin independently of each other.
To match some of the markings of the original tattoo, I carved some lines into the face of the heart. This was something I wish I’d done differently. Had I burned markings in with my soldering iron, I could have achieved a MUCH cooler look and been able to make a bit more intricate patterns. Lesson learned.
Oh yea, I also had to drill some holes for the copper tubing, chain, and mounting screws for the hook and switch.
Once all the drilling, dremeling, carving and gear placement testing was done, I gave the heart a good sanding and stained it. With the stain dried, I painted the carved channels black, to achieve that realistic, wood-burned look…/Sarcasm.
I put all the gears in first. Then I placed the motor in its cavity, aligned it to be in best contact with the first gear, and hot glued it in place. I then installed the hook, switch, chain/key, and battery holder. I hot glued the chain and copper tubing in place. The hook/switch are just screwed in. I used epoxy on the bottom of the battery holder, then used hot glue around the edges once placed.
The circuit is simple enough. It’s just battery positive –> switch pole 1, switch pole 2 –> motor positive, and motor negative –> battery negative. Done. I hot glued the wires down everywhere so they wouldn’t snag on anything at get ripped off. The connections at the motor were flimsy, so yea.
The Finished Product
Thanks for reading!