Walking Tapir Automaton
After making a simple snake automaton, I decided to build something a little more elaborate and challenging. So I present to you the ‘walking tapir’.
Tapirs are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk; but they are actually related to horses and rhinoceroses. Tapirs are endangered animals found in places like jungle and forest regions of South and Central America and Southeast Asia.
This Instructable shows you how to make the walking tapir automaton. If you wish to design a different walking animal you can replace the tapir body and legs with your own design; just copy the hole pattern into the correct positions.
Supplies
1/8" plywood, 1/4" hardwood e.g. maple
1/8" and 3/16" dia dowels, about 20" length needed
1/2" oak dowel for the handle, 7 inches
CA glue, wood glue
Laser cutter or scroll saw
Drill press
Design
First I did several prototypes of the automaton to optimize the design and figure out the best way to put everything together. As with many of my projects I designed the walking tapir using Fusion 360 software. This gave me a playground to tweak various design parameters and visualize the resulting movements. The mechanism is based on the Jansen's linkage. From the software I could also export the files for all parts to be cut on my laser cutter. You could use the same files to lay out the parts to be cut with a scroll saw, or even 3d print the project. I have included all files as well as an animation of the walking tapir.
Cutting the Parts
I cut most parts from 1/8” (3mm) thick plywood. The body however is a piece of 1/4” thick hardwood (maple). Axles are made from 1/8” and 3/16” diameter dowels. For glue I used CA glue with a spray-on accelerator.
You will need:
1x tapir body
8x long link, short link
4x triangle link
2x spur12, spur9 (these are the spur gears)
4x spur6
2x fore leg, aft leg
2x crank
30 (+) washers, have some extras handy
20x 1/8" dowel axles for the linkages, various length
5x 3/16" dowel pieces for gear axles and crank
Assembly
There are a few tricks to make everything work smoothly during assembly. I first assembled and tested the gear train. I then attached a 7" long 1/2" dia oak dowel to the body to serve as a handle. Make sure the axles (dowels) fit snugly thru the holes but still turn easily. ‘Lubricate’ all moving surfaces and axles with candle wax to reduce friction. Frequently test during the assembly, e.g. after adding another linkage to confirm everything still moves freely. It takes a little tweaking to have the mechanism function smoothly, so don't give up. When you assemble the second side of the tapir mechanism be sure to offset the drive gear (spur12) by half a turn so that the left/right legs move in proper relation to each other. Use washers as spacers to keep the linkages aligned. Glue the washers to the end of the axles to keep all linkages and gears secured, but be sure the mechanism still moves freely. Trim the axles flush after full assembly, gluing, and testing.
Lastly, I made a stand for the automaton, a simple piece of 1" by 1" by 8" wood with a 1/2" hole to hold the handle. The stand makes it easier to operate the walking tapir!
Enjoy!