Intro: Giant Mechanical Flipbook
Check out how fellow Instructables Artist In Residence Iris Gottlieb designed the animation, and the her process of etching out an image on anodized aluminum.
Step 1: Pick a Partner and Collaborate
This was a collaboration with fellow Artist In Residence Iris Gottlieb. She mentioned one day in a meeting that she wanted to build an animation, but lacked the mechanical skills to make it happen. She does some really beautiful drawings, and I was conveniently looking for my next project. We took inspiration from an existing mechanical flip book, but decided to go way bigger. And metal.
Step 2: Design Using Autodesk Inventor
I have attached the model in case you would like to build this yourself. Enjoy!
This was my first chance to learn Inventor. Once we settled on a scale, I started out sketching out concepts. I was initially thinking of having a handle on the front with a 90 degree power transfer, but I decided against it because it would impede the view of the flip book and was unnecessarily mechanically complex .
I went with a knob on the side and a sprocket connecting the hand crank with the drive shaft. I realized that all the panels were going to be out of anodized aluminum, so would be quite heavy. I did some gearing calculations and decided on a 4:1 gear ratio to get maximum torque.
The design consists of a large half inch thick acrylic box, with a spindle that holds the panels in a sort of rolling cage. The spindle would be connected to a sprocket which is driven via chain from the hand crank. At the top there is a piece of plastic to hold the panels in place.
Now it was time to make the design a reality. This was my first major moving mechanical project, and an excuse to use the waterjet.
Step 3: Choosing Bearings
For the shaft, I used plastic flanged sleeve bearings to have each end sit within the acrylic and spin freely. I lathed down the ends of the 1/2 in shaft to fit a 3/8in bearing, so it would hold itself in place.
Step 4: Cutting the Parts on the Waterjet
The hardware was custom cut using Pier 9's Omax waterjet. It cuts quite well through .25in aluminum.
Step 5: Waterjet:0, Tablesaw: 1
I couldn't get the water jet to cut my bolt hole patterns. It turns out that 1/2in acrylic is a very brittle material, and there is a special setting that ramps up the pressure up slowly. I tried every possible combination of settings, but the jet kept clogging. So in the end I ended up cutting it on the table saw in 15 minutes. Since it was all done by hand, the holes had to be hand drilled as well.
Step 6: Aluminum Side Brackets
Initially, I thought a tri-corner miter would be a good idea, but it turned out to not be worth the hassle. I miscalculate the thickness of the metal and they ended up shorter on all sides.
I also didn't realize that I ordered aluminum side brackets with an inside radius, so I had to grind them out so that they would sit flush on the panels. Always learning?
Step 7: Building the Box
This was the most time-consuming part of the entire project.
The aluminum side bracket holes had to be drilled using the mill to get a precise distance between the holes. I then used the existing metal holes as a pilot to drill through the plastic. It was assembled with 8/32 machine screws.
Step 8: Assembling the Spindle Cage
The spindle resembles some sort of wacky birdcage. It holds the panels in place as they rotate. The bars were 1/8in stainless steel shaft, ordered from McMaster Carr.
Once the parts were cut on the waterjet, I drilled holes only partially through the .25in aluminum and pressed in bronze bearings. These housed the steel shaft and allowed it to rotate freely when turned.
Step 9: Inserting the Panels
Time to test it all out. The box had to be partially disassembled to insert the shaft and bearings, but it fit in quite nicely. The panels were attached using Chicago Screws. Make sure to add loc-tite to your screws or one will rattle off and cause some damage.
Step 10: Drive Chain
I used ANSI #25 chain, and various combinations of sprockets to get the ratio right. Here you see the attachment of the handle, and the layout of the chain. I found it's important to keep a bit of slack on the top driving portion of the chain so that it doesn't hop off. The handle mount hardware had adjustable sliders to get the perfect chain tension.
Step 11: Insert the Flapper
I chose .25in delrin because it's flexible and incredibly strong. Its purpose is to hold the top panel up and then flick the next image into place when the spindle is turned.
The depth of the flapper is critical. It has to sit at the very tip of the panels, and run perfectly parallel to the shaft.