As we enter the final hours, I have completed what I thought would be impossible. The Tipping Tophat finally tips, bringing my kooky idea to reality.
When I first began work on the hat, I had a rough idea of how it was going to work, except that I had no idea of the challenges I would encounter as it all came together.
The biggest issue here was space. It turns out dolls aren't as small as you would think and getting half of one inside a hat, with room to spare, is quite a squeeze. Luckily I had almost exactly the right amount of space. Occasionally on the way up, he catches on the lid slightly but I can avoid that by being gentle.
My second crisis issue was that the servos I used didn't have quite enough power when running off the rechargeable battery provided in the kit. Fortunately, the kit also included a second connector and I had a spare 3xAA battery holder lying around, which was just enough to get it working reliably.
One thing that I hadn't thought much about in the beginning was a mechanism to open the hat. Working with a limit of only 3 data pins, one of which I reserved for the triggering button, meant I had to work with only 2 servos. This limitation force me to look into a pushrod system, where the raising of the main arm pushes a rod towards a hinged arm at the back, which in turn pushes up and opens the lid.
Getting the arm to move turned out to be a lot easier than I had imagined. The doll itself already had a simple shoulder that rotated, so with just a dab of oil, the tip of a servo horn and another push rod, I had my own little roboman. The servo for his arm is mounted into the main hinged lifting arm, so it comes up when he pops out of the hat.
Internally, this hat is far from glamourous. It's a mess of wires taped to the edges, with enough room to move as needed. While it doesn't look great, it gets the job done.
This was a fun competition, albeit stressful and frustrating, but ultimately I'm glad to have been part of it. I plan to release the 3d models for this build soon, but I think I'll finalise a few parts first.