For my 2D drawing, I selected Mechanical Movement #68 from the website 507 Mechanical Movements. This mechanism caught my attention because of the gears’ unusual shapes, particularly the way in which the right gear’s teeth hug the left gear. This stops the right gear in a way that is integral to the system, holding it in place while it is not being driven. I was also interested in how the mechanism creates brief, intermittent motion, something like the ticking of a clock. Below are the two images of the system provided by the website.

 

 

 

 

 

 

The mechanism’s description is as follows: “The single tooth, A, of the driving-wheel, B, acts in the notches of the wheel, C, and turns the latter the distance of one notch in every revolution of C. No stop is necessary in this movement, as the driving-wheel, B, serves as a lock by fitting into the hollows cut in the circumference of the wheel, C, between its notches.”

In recreating this design, I began by loading the sketched design into Adobe Illustrator and using Live Trace, but it was immediately clear that this tactic wasn’t going to work. As shown on the right, the lines break in several places, and many areas are thicker than others. Refining this drawing into something usable would take longer than simply drawing the mechanism from scratch.

However, I decided to give Live Trace another shot, this time using it on the animated version of the design. Given the fact that this image was clearly created on a computer, I thought that it would have fewer inconsistencies in line width and continuity, etc., so tracing it should yield a more meaningful result. Most of the different types of Live Trace actually produced results that were even more incomplete, but the “Silhouettes” trace (shown on the left) held promise.

Nevertheless, upon inspecting the silhouette trace’s curves up close, I found that there were still many inconsistencies in line width, as well as strange curve abnormalities as shown on the right. Considering the amount of time that would be required to manually fix all such inconsistencies, I decided it was finally time to stop searching for workarounds and simply draw the mechanism from scratch.

I began by importing a .png version of the animated design into Illustrator, locking it in place, and creating a new layer on top of it. I used the locked image to trace the system onto the new layer, thereby ensuring that all components were recreated at the same scale as one another.

I started with the left gear, creating circles that marked its main outer edge as well as the front and back edges of the tooth. I then traced the sides of the notch to the left of the tooth with the pen tool, and I used the reflect tool to copy those lines to the right side of the tooth. With a few uses of the scissors and join tools, I had a complete single-toothed gear.

Moving on to the other gear, I started with a circle to capture the inner edges between each notch. I then traced a tooth of the gear, using a copy of the previous gear to ensure that the new tooth fit snugly against the old gear’s edge. I used the rotate tool to copy nine identical and evenly-spaced teeth around the circle, and with a few more uses of the scissors and join tools, the second gear was complete.

In preparing the file, I positioned the two gears apart rather than snugly pressed against each other so that the file could be more easily laser cut, if need be. I also refrained from the large, double-circle bores cut through the gears in the animated design, instead settling for a single circle with a 0.5-inch diameter, as I figured a smaller bore would be more appropriate for most laser-cut applications. Lastly, all of the strokes in my Illustrator file are 1pt so that the curves would be easier to see and work with, but if this design were to be laser cut, the user would need to change the strokes to 0.001 inches, in addition to possibly rescaling the design or altering bore diameters to fit the particular application.

The final Illustrator file is shown below and can be downloaded here.

This Illustrator exercise was interesting, and it taught me that you certainly can’t rely on tools like Live Trace for everything. Sometimes, the fastest way to do something is to do it from scratch. I also gained experience with the reflect and rotate tools, which helped ensure consistency throughout my gears. I’d be very interested to laser cut this system and see if I traced my gears well enough that they’d fit together well enough to function properly. Regardless, I feel considerably more comfortable using Adobe Illustrator now, and I am excited to use it on future projects.