For my midterm I created a windmill. I found the mechanics on 501 mechanical movements and decided that I liked the way that it all came together, so I used that movement for my 2D drawing homework and expanded upon it for my project. To begin, I created an adobe illustrator file for my pieces. I knew that I wanted the machine to have two distinct parts- a windmill portion and a support structure.

The windmill would sit on top of the support, with a steel dowel connecting the two.

The support structure was designed with four legs to maximize stability, all while holding the dowel securely in place. The windmill portion was designed to sit above the supports, suspended by locking collars above and below. I used bearings throughout the windmill to ensure smooth rotation that wasn’t dependent on wood sliding past itself, which I have seen fail in other pieces. The bearings will also be more long-lived than wood joints.

I created the windmill part from aluminium using the plasma cutter and the support from laser cut wood. After plasma cutting the aluminium, I sandblasted it to post process it after heavy filing. I prefer the sandblasting due to its ease, speed, and final product.

To begin creating my design, I created a prototype of the support structure and the auxiliary parts of the windmill. I cut cardboard first so that I could test the finger joints within the support structure.
Here we can see the slot joint for the support system, which I had to tighten a little bit. I pretty much did all of the tolerance tightening by eyesight, and for the cardboard that worked well. Once I got into the wood, however, my tolerances were definitely off on the versions of the piece shown below. I don’t quite know what went wrong but I cut it once and it fit perfectly, then the second cut on the same piece of wood 10 minutes later led to a bad fit. Below you can see the cardboard, beneath that, the wood version.
The laser cutter was busy by the time I figured out these didn’t fit, so instead of cutting new ones I just sanded down the pegs to be able to slot in and get press fit. Was it perfect? No. Did it work? Yes.

Ok back to the prototype.
Once put together, the prototype looked like this. I liked the support network, but decided to slim it down by cutting out the extra parts of the circles and stabilize it by adding additional slots on the horizontal rings to prevent any sort of sliding. It should be noted that I used a steel rod as the center axle. The changes are shown below. You can see the horizontal supports are now crosses as opposed to circles, and the joints to the vertical have both slots in the horizontal piece as well as the vertical. This creates a much more stable connection that can move neither vertically nor horizontally. The steel rod is also press-fit into the wood, keeping it very secure to prevent rattling in the wind. 

Here again we can see the prototype. This prototype went well but required a few re-cuts. I was planning on using bearings to promote easier spinning but they hadn’t come in yet so I left those slots open. It was time to move on to the final product. Once the bearings came in, I had to file down the aluminium asterisk to allow the bearings to fit snugly.
After filing the aluminium down, I epoxied the bearings into the aluminium. This was successful and resulted in a tight binding of the bearings to the aluminium base, with no issues surrounding usability of the bearings. A downside to the epoxy is that it didn’t end up looking very good, and didn’t always dry with the bearings totally flat in their holes. I mitigated the aesthetic issues by putting all of this goop on the bottom side of the rotary piece, so the top is totally clean. After placing the bearings into the aluminium base, it was time to start cutting the wood. The first cuts weren’t perfect, and required recuts. I took notes on the old wood to allow me to alter the future cuts easily at the laser cutter. Once I was happy with all the cuts, I post processed the wood by sanding it then using beeswax to give it a nice sheen.
Hand sanding these pieces made my arm extremely tired, so I threw together a tool to make it a bit easier!

After adding the beeswax, which was really convenient because it only took about 20 minutes and looked really nice, the wood turned out like this. I learned that finishing the wood is always the right move with laser cut pieces.

Before post processing, I partly constructed the pieces to give it a quick check, but I mainly focused on the support, without trying the windmill. This was a big mistake as I had accidentally made the dowels connecting the panels to the aluminium too short. This was an easily fixable mistake if I had just recut the panels with the peg holes closer together, but since the panels I had were already through an hour long post process I decided to just make it work. The dowels weren’t stock either, and had to be sanded carefully to fit into the bearings at the ends of the rotary part of the windmill. Because each dowel took about 10 minutes to make, I was loath to redo all of them since they were too short, so the easiest solution would have been to recut the panels. Instead of doing that, I just made it work by shoving them together and dealing with the weird angles created, which didn’t end up affecting functionality, but did affect aesthetic.

After all of this was together, I joined the windmill to the support via the locking collars and there it was! My windmill! I wasn’t able to make it work quite right with my lungs, but once I got a hold of a fan, woo-eee! It was SCHWEET! Here is a video showing it working, notice how the panels swing out of the wind to avoid slowing it down, but back into the wind to get pushed. For some reason only turbulent air worked… Here is a link to the video. IMG_3090-2luv8an

This puppy was ExPeNsIvE. At least 2o work hours, at $40/hr that’s $800. Plasma and laser cutter time would run me at least $100 at a local makerspace. The wood cost $10, plus $5 of dowels, the aluminium $20. The bearings were $25, the epoxy was $30, the locking collars around $8, and the steel dowel was $10.  Total $1,008

All in all, it was 35 individual pieces to make one doohicky, and I’m extremely happy with it, it is definitely the most complicated thing I’ve ever built!