Wednesday, June 8, 2016

Building a Harmonograph for Science Fair

Difficulty Level (Easy, Medium, Hard, Insane):

For our second annual home schooling science fair, we decided to introduce our son to harmonics and machining by building a harmonograph. I had seen my first harmonograph many decades ago in a science museum in Switzerland and having a significant background in mathematics I have always been fascinated by those machines that create beautiful, yet mathematically predictable pictures.

Aside from teaching him how harmonics work, how two one-dimensional axes (x-axis & y-axis) can interact to make a two dimensional image I wanted to introduce him to work on the lathe as well as to teach him how to be consistent, determined and “suffer” through the “boring” spots in the creation of a project.

There are several people online that have created these out of wood and i have made a few of these myself with small sticks of wood joined together by rubber bands, but this time around I wanted him to create something a little more substantial.

The pendulums were made from ½” solid round bar, the pivot points were made from 1” diameter teflon held together by 1/8” roll pins. The table was made out of 5/8” MDF and the horizontal arms that joined the pendulums to the pen were made out of ½” wood dowels.

The first thing we had to do is cut two 1” pieces of 2” diameter pipe, then drill and tap two holes on oposite sides. The next thing was to cut two 12” pieces of metal and turn a pivot point in the end. Then, we had to thread a ½” by 13 TPI thread to connect the pivot point pieces to the round pipe.

The next thing was to cut two ½” pieces of solid round bar and thread one end to a ½” by 13 TPI thread to connect to the second hole in the round pipe. After that, we cut up the wood dowels and drilled two holes for the cotter pins.

Then, we had to turn three pivots and a pen holder out of teflon. The last thing was to create two pendulum weights with a brass adjusting screw.

After cutting a 32” round table with the router and the circle attachment I made from some plexi glass many years ago it was ready to put together.


Nate cutting off the first two pieces on my metal band saw
Working hard at tapping the 1/2" by 13 TPI female thread
Ninja Nate
The two cut, drilled and tapped pieces
Proud boy
Turning a pivot point in one of the pendulums
Working the lathe
The first pendulum finished
He said he was Loki with his weapon. What a kid!
Close-up of the pendulum suspension method
Making the pendulum weight adjustment knob
Getting ready to mill the teflon pivot connectors
Drilling the holes on the mill
I think he liked it
Some of the samples
Some of the exhibits from the story above
Nate making some pictures
The judges from Mad Science observing his project
Nate demonstrating how it works to the judges
Some participants trying it out for themselves
The award ceremony
The price he won for his participation
Close-up of one of the pictures
Another one
Another one
The pen mounting contraption
A triple color picture
Metal Band Saw
Metal lathe & accessories
Measuring tape
Drill press
Drill bits
Cordless drill
De-burring tool
Angle grinder
Bench top grinder
Center punch
Circle attachment for router

2” of 2” diameter pipe
6’ of ½” solid round bar
8” of 2-1/2” solid round bar
4” of 1” diameter solid round brass
12” of 1” round teflon
3’ by 4’ of 5/8” MDF
8” of ¼” by 1” flat bar
Three 1/8” roll pins
4’ of ½” wood dowel

$35.00 (for the MDF; I didn't have any on hand)

20 hrs

The project was a great success and we had so many kids absolutely fascinated that two pendulums could create such elaborate drawings with no electricity!


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