Friday, June 22, 2012

Tada! Homemade Shake Table

Isn't it so pretty?  I am so excited about completing this shake table lesson plan, as it was a favorite of mine as a kid.  It actually took some engineering thinking to completely enclose it and give me all the features I wanted.  I also got some much needed practice soldering.

Here's what I did:

1. Based my design around the Exploratorium's homemade shake table - mainly a 1.5-3V motor spinning an offcenter weight (wingnuts and washers), with a potentiometer to vary resistance and shaking speed, which runs off of 1-2 D sized batteries.  I kept the same base and shake table sizes, along with the square edge lining.  The top is still attached to the bottom via rubber bands.

The innards of the raised shake table
2. Completely redesigned it to stand on 4 pillars (~3 inches tall), so I could mount the motor on the underside. I super glued milk caps (instead of film canister lids - who has those nowadays anyways?) to the pillars to house the marbles the shake table sits on.
3. Adapted the circuit so it can run off of batteries or AC (plug into a household socket).  For this I got a power adapter that goes down to 3V.  I found a plug for that adapter and bought an extra plug of the same size, which I soldered to a plastic 2 D battery holder.  Since I want to do this in places without running electricity (like the park tomorrow) and I didn't want to waste batteries if I go into schools or do this at community centers, it was an important feature for me to have both options.

4. Added an on/off switch to the circuit.  Who doesn't like turning on a switch and being in control?

On/Off switch + variable resistor (potientiometer)
5. Since I wanted it enclosed, having rubber bands sticking out in the bottom wasn't going to work, so I took small eye screws that came in a wall mounting kit we bought moons ago.  I opened each hook up slightly (enough to insert a rubber band without breaking it).  I mounted four screws on the underside of the shake table ==> one at the halfway mark of each side.  I made sure they were mounted directly under the piece of wood on the end of the shake table.  Four more screws were placed on the plywood base, 3 inches back from each side on the mid-line.
6. The motor was mounted on an extra block of wood I had leftover from raising the table up 3". My husband made a custom mount piece using his 3D printer.
7. For the enclosure, I created a drawing of what I wanted and cut 0.25" thick alder board with the laser cutter in a puzzle-like interlocking pattern.
8. To keep the top from falling down, I super glued small metal L brackets/corners on the side piece which allowed the top to be flat but not glued to it (I want to be able to remove the top pieces).
9. The two sides with electronics on it were fixed to the plywood base and each other via wood glue.
10. The two remaining sides were attached to the fixed sides and each other via cabinet magnets.  I wanted to be able to remove the top and access the underside of the shake table if anything (like the rubber bands or motors) decided to poop out on me.

Then of course Big J and I tried out the marshmallow structures before the kids and successfully made ~12 inch structures out of 40-50 toothpicks.  Mine was taller and was stable on the shake table, buuuut, it collapsed on itself overnight which is fine - it did what it needed to do.  I called it the giraffe (on the shake table below).


  1. Honestly, my first thought was that it looked very pretty! Nice work!

    1. I was asked multiple times in the park today if it was a kit. Maybe I should think about making it a kit :-)