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Picture of Torus Drawing Machine

This is a machine which draws a torus. It is based on a ruler, two modified servo motors and some 3D printed parts. One of the motors has a 3D printed wheel attached with offset mounting holes. The marker slider is attached to this wheel with a metal linkage. As the 3D printed wheel turns, the marker slider moves back and forth linearly across the ruler. At the same time the other servo drives the entire machine in circles around a center pivot using a skate wheel. These two simultaneous movements ultimately move the marker and draw the torus design.

This was created to help support a 7th grade curriculum, but surely can be used at other grade levels. See the attached lesson plan for how you might use it in the classroom to explore area and circumference.

If you are looking for a machine for younger students that demonstrates simpler mathematical and engineering principles, check out the Circle Drawing Machine.

Step 1: Materials

Picture of Materials

(x2) Continuous rotation servos (modified for direct drive)***
(x1) 12" Ruler
(x1) 3D Printed sliding marker bracket
(x1) 3D Printed servo skate wheel hub
(x1) 3D Printed offset wheel
(x1) 3XAA Battery Holder
(x3) AA Batteries (not pictured)
(x1) Sharpie marker (not pictured)
(x1) 76mm Skate wheel
(x1) 3/8-16 x 3" Bolt
(x1) 3/8-16 Nut
(x20) 3/8" x 2" Fender Washer
(x2) 1/4-20 x 3/4" Thumbscrews
(x1) 1/4-20 Nut
(x2) 1/4" Shaft collars
(x1) 10-32 x 3" Threaded rod
(x1) 5.5mm male screw terminal power plug
(x1) 5.5mm female screw terminal power socket
(x4) Rubber adhesive feet
(x2) Self-adhesive zip tie mounts
(x3) 8" Zip ties
(x4) 4" Zip ties
(x1) Large sheet of paper (at least 12" square)

*** See Step 3 for more details about modifying a servo.

mtairymd5 days ago
Very cool....nice job!
stoppi715 days ago
Hi! I don't really see the sense in making this project with my class? What do they learn from this except drawing a torus?
As already commented by Naevus Spirograph produces similar curves (hypotrochoids?) and with gearing it closes the curve, achieving a precise pattern, whereas your machine would - I suspect - eventually fill in a solid black ring, if left to run
Any chance of adding a video of it performing?
Naevus6 days ago
When I was a kid, I had this:
Amazing project Randy! This goes to my personal list of projects to build one day!
AussieAlf9 days ago
Hi Randy,
Got a video? Would love to see it in action.
Cool project
randofo (author)  AussieAlf9 days ago
Here is one I made while testing:

Perhaps I will make a better one eventually and put it in the Instructable.
That's so cool..nothing wrong with that display.