Saturday, January 7, 2017

LogoTurtle Bump Sensor

I designed a bump sensor bracket for the LogoTurtle that you can 3D print and add to your LogoTurtle. The model was designed for the laser cut version of the chassis. However, with longer battery holder screws it could easily be attached to the 3D printed chassis as well.

The bump sensor is built around a small rocker switch.

I soldered two wires to the switch and soldered the wires to the LogoTurtle board. The ground connects to pin A2 on the Metro Mini through a 10K resistor. The positive wire from the switch connects to the positive rail on the LogoTurtle board.

The switch sits behind a tongue depressor that has two one inch springs behind it. The switch activates if the bumper is pressed nearly everywhere along its length. The sensitivity of the switch can be configured by moving the rocker switch closer (or farther) from the bumper.

A simple Logo procedure can be uploaded to the LogoTurtle to have the turtle drive until the switch is activated. This example backs up 200 then turns somewhere between 10 and 360 degrees before going forward again. This procedure could be made more "sensitive" by having the LogoTurtle drive a shorter distance before it polls the switch data.
to startup

to bump
ifelse a2 > 1000
[bk 200 rt random 10 360]
[fd 100]
This addition to the LogoTurtle adds functionality to this robot: in addition to making beautiful art, the LogoTurtle now can be programmed to behave as a roaming, autonomous robot capable of navigating flat terrain with obstacles. 

3D print yourself a bracket and upgrade the functionality of your LogoTurtle!

Tortoise and Hare Automaton

Over winter break from work I built a "Tortoise and Hare" automaton, based on the nursery tale. I used some of my 3D printed automaton parts that I used in my "The Cow Jumped Over the Moon" automaton, refining them slightly.

Again, the automaton was housed in an upcycled cigar box. These boxes are well made, inexpensive, and are the perfect size for a small, hand-held automaton.

This automaton used an oblong cam, a round cam, a round cam follower, and a pivot to produce two different movements from the hand-cranked mechanism.

The parts were 3D printed in ABS at .3mm layer height, 10% infill.

The tortoise and hare models were remixed to size them and to add an attachment for the dowels.

I used square dowels to insure that the cams do not slip. The pivot is connected to a push pin.

The grass obscures the dowels a little and adds to the narrative of the automaton. It was programmed in TurtleArt then imported into Tinkercad for extrusion and sizing.

I decoupaged the cigar box with the TurtleArt blades of grass design. I printed the design on an inkjet printer then put it into the freezer overnight so it would not smudge when I put the Mod Podge on it.

The finished automaton is whimsical and fun to play with! The box top slides open to reveal the mechanism, or can be kept closed to preserve the mystery of the movement.

The movements complete the narrative: the tortoise plods along while the hare spins freely on the cam and gets nowhere fast.


It was fun to revisit the nursery tale theme for automaton inspiration. I had fun with my first decoupage project and can see doing more of this fun craft. The 3D printed parts I developed earlier were helpful in rapidly constructing this project. 

Friday, December 16, 2016

Cardboard Pinball Game

Inspired by a build at CMK16, I decided to build my own cardboard pinball game. It took me only a few hours, with a few improvements added in the following days.

The flippers are build around pencils, a piece of balsa wood, tongue depressors, and rubber bands. The balsa is glued to the inside of the box (I managed to give myself a second degree burn with the hot glue attaching this piece). This piece helps keep the pencils properly aligned.

The tongue depressors are attached to the pencils with rubber bands. An additional rubber band pulls the flipped toward the player, so there is a return to the flipper when they are flipped.

The marble launcher is built around a chopstick, a spring, and another piece of balsa. It is super powerful!

My boss suggested adding a flap since the marble had the tendency to end up back in the chute.

A small flap of cardboard catches the marbles that the player misses as they roll off the platform.

This was a fun and easy build that has me excited to perhaps build a wood version of the game over the holidays.

Thursday, December 8, 2016

Interactive Displays

When I interviewed for my job they took me on a tour of the school. I was struck by the five enormous tanks they have in the middle division science lab, and I wondered about the different organisms that lived within. 

When I was hired one of my first thoughts was to collaborate with a science teacher to build displays to identify the animals in the tanks so everyone could learn more about them. I found a willing collaborator in 7th grade science!

I started by designing 3D printed brackets in Tinkercad. These brackets would clamp onto the window uprights in the hallways outside of the science room (the tanks are visible from both inside the lab and in the hallways). 

The beams were made from 36 inch balsa, which is light and flexible. A second bracket was added to make sure the beam did not flex too much.

The original display was prototyped in cardboard. It contained a paper circuit switch that closed when the photo of the organism was pressed. When the circuit closed an LED in the bottom the box lit up.

Once the prototype proved to work, I went to the Columbia University Maker Space to use their laser cutter to fabricate boxes from wood. I used to generate a PDF of the box. The second prototype was fabricated the same size as the cardboard box.

Mounting the wooden box on the beam revealed that the box was too far from the windows, causing the beams to flex too much. Considering the amount of use the boxes might need to withstand, I redesigned the brackets to hold the beam closer to the window. I also revised the box design, reducing the depth to one inch.

After leaving the display in place for a couple of weeks, the beams were not holding up to the daily use. I decided to double up the beams during construction.

The seventh grade researched the organisms that reside in the tanks and wrote short paragraphs about them using a prompt.

I pushed into the class and helped the students assemble the boxes. They started by building the circuit in the box then finished by assembling the boxes. The beam ran through the back of each box, securing it to the beam.

The students measured the spaces between boxes to cut secondary beams. They were glued and clamped to the primary beam.

The switch has a piece of sheet protector glued to it. Since there are more organisms than boxes this allows the teacher to rotate the students' work into the displays.

Overall, this was a great hands-on project that improved the tanks immensely. The students worked hard on assembling the boxes and writing the informational text. The entire school benefits from the information!