I have made a few ramp walking toys, not always successful, mind you. It seems to be a matter of luck and persistence.
Many years ago, in my travels around Australia, I saw an example of a ramp walking wallaby.
It was quite small, about the size of a matchbox, and all you had to do was to touch the tail to get it to walk down the ramp.
A short history of my journey into the art and craft of making ramp walking toys. Also known as passive dynamic walker.
As much as I like making things, enjoy making things that move even more.
It all started with the Ramp Walking Rhino, a design by Robert Lou Ma. I made one, and it kind of worked. I think the problem was a small hinge, which I did not have, so I used a piece of piano hinge instead.
The challenge with these toys is to minimize friction, and the hinge was not sturdy enough to prevent the back leg rubbing on the body.
Tried making a different kind of hinging mechanism, but that ruined the geometry and I lost interest.
No hinges in this one, and I recently bought a scroll saw, so this seemed to be a good pattern to practice on.
It worked pretty well this time, but not being able to leave well enough alone, decided to figure out how and why it worked. If I can observe and describe the action, then I have a better understanding of how it works.
So here goes:
I made a copy in AutoCAD and pin pointed the center of mass of the body in relation to the pivot point and the center of mass of the legs, as shown in the image above.
Using movie maker to pause the video and take a screen shot, cropped each frame to remove the background distractions.
On the horizontal, this is the natural resting position. On the
ramp, give it a little shove and it starts walking.
The legs have hit the back stop and it is about to tilt forward.
front paws, about to tilt just a little more to allow the legs to
rotate forward. If the ramp is slightly too steep, it does in fact
tilt onto it’s nose. Makes me think the front paws need a little
The legs have come forward and hit the front stop. It is about to rock backwards.
Tilting backwards and the tail hits the ramp. Starts to slide forward.
Wonder if I should put a little wheel in the tail?
Starts all over again – very much the same as frame 2 – The legs have hit the back stop and the tail is lifting off the ramp.
And so it goes. If the ramp was long enough, it would go on forever.
A ramp walking toy made by Roberto Lou Ma.
I have made a line drawing template that you can print onto a piece of paper and paste it onto a piece of wood and cut it out with a scroll saw.
This design is my first attempt at making a ramp walking toy. Designed by Roberto Lou Ma, retired civil engineer, cartoonist, automata & toy maker.
In response to a request from Eric, I went looking for ramp walking duck plans.
There are many images of ramp walking ducks that you can buy, including a few videos you can watch, but alas, not too many actual plans or patterns to make one.
Here is another scroll saw pattern for a ramp walking duck.
At the moment it is a work in progress, as they say.
I encourage you use the templates to conduct your own experiments.
This is a whirligig scroll saw pattern that I found on Azwoodman.
I think it would make a great ramp walking toy.
My brain cannot handle this stuff, but here is a poster which should serve as an introduction to how ramp walking toys work.
By Meghan Murray and Professor Chris Lee.
Famous at last.
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