Introduction

For this project, Justin and I embarked on making an escapement mechanism out of laser-cut wood, glue, a little metal, and a lot of hard work. We knew the road would be tumultuous, yet we still gave it our best and ended up with a product we are both mildly satisfied with.

Gate 1: Designing and Brainstorming

Our first step was the pick which mechanism we wanted to make. After scrolling through the 507 mechanical movements website, we settled on number 303: a dead-beat pendulum escapement. Justin had wanted an excuse to make a clock for a while, and I thought it was a neat idea so we started looking at how we’d go about making this mechanism, as it is quite difficult to get right. We recognized we needed a counterweight to spin the pointed gear, a pendulum to drive the mechanism, and gears to control how fast everything moved. I got to work on sketching up the gear ratios and Justin started making a CAD model of the mechanism.

• Left is the gear ratio to slow the fall of the mass needed to rotate the pointed gear.
• Middle is the escapement mechanism itself.
• Right is to slow the rotation of the clock face. (Image is very compressed for some reason)

<–CAD model of escapement mechanism

Gate 2: More CAD and Conceptual Thought

Justin made a preliminary CAD model of the escapement mechanism so we could ensure the gear ratios were correct and could fit together in a reasonably sized footprint. As you can see in the photo below, the gears do not perfectly fit in the box at this point as the gears are massive. For reference, the structure is over two feet tall to provide ample room for the pendulum to swing and the counter weight to fall. In this design, we also had the escapement on the outside of the box which we later slide inside the box since the pendulum has to have a way to touch the pointed gear.

<–Justin’s awesome CAD model

Gate 3: Construction Time!! 

We now started cutting gears out, making dowels, and utilizing our outside resources to get nice bearings. Laser cutting everything out probably look close to an hour and half since the project was so large and required a lot of gears.

We then realized that none of the dowels in the OEDK fit the smooth bearings Justin brought in, so we started looking at methods to make them fit. First we tried getting a box cutter and whittling down the ends by hand. When that didn’t work we tried using the belt sander and rotating the dowels manually. This made the dowels sit in the bears as an angle, so we needed a way to both rotate the dowel and sand at the same time. We thought of the genius idea of putting the dowels in a hand drill and taking it to the belt sander… do not do this it doesn’t help at all. The actual solution, though very tedious, was to put the dowels in a drill press, turn up the RPM, and hand sand them down until they fit. 

 

Notice, Justin wears safety glasses so this is safe  —>

We then went into spacing out the gears on the new, sleek dowels. Initially, I just eye-balled where they were supposed to go, and after a while I realized the CAD model already had measurements that theoretically worked. So I put the gears in order and taped them down to keep them in place and avoid slip between the gears and the dowel. This remained a problem for the duration of the project, but we found a smart way to mitigate the effects of no having perfect a perfectly fitting gears.

For the structure, we used the very large dowels and laser cut a base. With all the components laser cut and gears on the dowels, we started putting the structure together and ensuring the weight could move the gears so the mechanism could spin.

 

 

 

We ran into a little problem of the gears being too big for the box, so we used a dremel cut out a portion to make it ensure there wasn’t any rubbing. 

 

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We then figured out that the gear ratios and weight we used did not work, so we decided to downsize and start testing the gear sizing and counterweight mass using a setup on the right.

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^^Video of the escapement mechanism working for a little bit (we were very happy to get this on tape)

Final: Putting a Bow on This 

Following Gate 3 one of the issues we noticed was the pendulum would lose energy too quickly. We believed this was due to the pendulum not being weights so we planned to fix this by water jetting weights to attach to the bottom of the pendulum to make it heavier and move its center of mass further down. However the water jet was down so we had to wait all the way till Monday (the day the device was due…) to water jet the counter weights. We water jetted the counter weights out of brass for a variety of reasons: it matched our steampunk aesthetic, I was a good weight to weigh down the pendulum without breaking it, and it was one of the few sheets of metal to cut out the weights from.

Following this our device was ready and just needed to be post processed, assembled, and then the final tweaks/touches. Joseph and I had planned on doing the post processing and final touches Monday evening – Justin had a robotics competition Sunday and an exam Monday morning :(. However at approximately 4pm we realized that the device was due at 6pm Monday not as 12pm Tuesday when we thought it was. What proceeded was some of the fastest post processing I had ever seen.

We quickly cut out the name plate and vinyl sticker to attach to our final device. We then planned on staining the gears and spray painting the other components. However we ran into quite a few problems while staining. The stain was much thicker than what we had previously used for the crate and it struggled to absorb into the wood (especially the dowels). We also applied too much stain and the stain added slight but non-trivial material to the parts. This caused problems since the gears no longer smoothly moved together and a good deal of friction. In hindsight we should have spray painted and not stained and moving components since that would have not added as much material.

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Stained gears and dowels^^                                                   ^^Spray painted escapement and structure

This extra material also caused issues when fitting the gears onto the dowels because the snuggly fit gears were now too tight. We used a heat gun to slightly melt the stain so the gears could be adjusted but this was far from ideal because it caused difficulty aligning the gears.

The good news is the structure of the device worked without issues. We spray painted those components silver and the spray paint did not interfere with the tolerance so everything fit together snuggly but smoothly as designed.

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Reflection

While the device does not fully work as we hoped we are still very proud of the project. While troubleshooting we came up with a list of improvements that will hopefully get the device to function –

• Water jet the escapement mechanism out of aluminum to prevent the tips of the teeth from breaking
• 3D print the gears in the gear box for the following reasons
  • The gears could be 3d printed onto the axle to ensure they do not become uncoupled
  • The gears would be better aligned in the 3rd dimensions
  • The gears could be made much wider to prevent them from slipping off of each other
• DO NOT DO any post processing that adds noticeable material to any moving/rubbing parts

After so many hours put into this project we might implement these improvements after the assignment is finished to finally get it to work.

Cost Analysis

Laser Cut Wood – $36.08

1” dowels – $23.94 ($5.98 each)

⅜” dowels – $5.04 ($1.26 each)

Bearings – $9.99

Stain – $5 (less than one can)

Spray Paint – $1 (less than one can)

Brass– $218

60 hours of labor at $10 an hours – $600

Total Cost: $899.05

Clean Workspaces—>