http://507movements.com/mm_152.html
The way this works is by the two studs going in and out of the cross piece with rectilinear movement. The bar has two studs, one going in the x-direction and the other going in the y-direction which travels the indented middle part of the cross. The end of the bar is attached to a pencil so the ellipse can be drawn.
When the studs line up in the major axis, the movement speeds up because that is when the middle stud(x-direction) comes to its end and the other stud runs through the y-axis. When the studs line up in the minor axis, it slows down because of the stud going in the y-direction makes the turn.
The key point of this mechanism is the different linear velocity that the studs move by. While in the x-direction is in constant velocity, the stud in y-direction is not at constant velocity as it speeds up as it is going up and down and slows down as it is at the ends trying to change direction. This is what makes the pencil draw an ellipse and not a circle.
I chose this design because I was simply astonished by the idea to use mechanics to make a ellipsograph. Also because I liked how this used something very simple and fundamental like studs but by combining the linear motion of two directions, it made it possible to design such mechanism. I was reminded of how important the basics is when it comes to engineering and how its more crucial to understand how each and every part works to make something fully functional.
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http://507movements.com/mm_376.html
Just a large-scale one that uses literally horsepower:)
http://507movements.com/mm_270.html
This mechanical movement is a pulley with an anti-friction bearing but I couldn’t quite understand what makes it anti-friction…
This is a super cool mechanism! I also love ellipsographs. Its interesting to read about the mechanics behind it. Looking at the picture, it was a little difficult to understand the movement of the mechanism but your description really helped!
I looked at this mechanism too! I really like how you described the inner workings of the mechanism and spoke about the physics behind its movement.
This is a great example of how different mechanisms can look from one another, this one having no teeth at all! The way you explained the movement made it much easier to imagine.
Wow, I haven’t thought about this in years, but I had this toy/fidget as a kid (Fig. 6), maybe it helped me become an engineer 🙂
http://americanhistory.si.edu/collections/object-groups/ellipsographs
For your last link, it’s not literally “anti-friction” but roller bearings, assumed by the animator, generally minimize friction as compared to a more traditional pulley. See more here: https://en.wikipedia.org/wiki/Rolling-element_bearing