Archive for the ‘Drawing Machines’ Category

The Gathering for Gardner 12

I was privileged to attend the 12th Gathering for Gardner.  This is a biennial conference celebrating the interests of Martin Gardner.

He penned the Mathematical Games column in Scientific American for 25 years and also wrote about science, skepticism, magic and philosophy.

Here are a few pictures, I’ll post more details later.

 

 

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The Hill Country Science Mill Opening

Valantine’s Day was a great day for the Science Mill opening in Johnson City Texas.

http://www.sciencemill.org

The Science Mill is a new science museum geared to middle and high school students and their families.

The mission of the museum “… is to ignite the curiosity, ambition, innovation and problem-solving potential of the next generation through an innovative, immersive experience that enhances the community’s understanding of, and appreciation for, science, technology, engineering and math (STEM).”

I was privileged to show both a new Van de Graaff generator and my  Lissagraph drawing machine at the opening.  Enthusiastic Members of the Texas 4H did a great job of demonstrating the Van de Graaff generator as you can see in the gallery below.

My drawing machine and Van De Graaff generator were temporary exhibits for the opening.  My wife, Sally Weber has three holograms which are part of the permanent exhibits at the museum.

Please support the new Museum!

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Heading to Houston Mini Maker Faire on Nov. 1st

Houston mini maker faire

 

I’ll be showing my Lissagraph II drawing machine.

Come by and say hello.

 

Yea,the word your trying to remember is Spirograph… its not that, but kind of like that only motorized and huge.

Otherwise, just like that.  It’s resemblance to any mouse-like cartoon character is purely caused by design constraints driven by gravity.

(Scroll down below the picture to read some design details.)

Craig_techshop

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Lissagraph Construction Details

By Craig Newswanger

Mechanical Details

The X and Y cranks are driven through toothed belt drives with a 5:1 ratio. The large turntable for the paper uses a direct friction drive with a rubber drive roller attached to the stepper motor. The friction drive method was chosen for the large turntable to avoid backlash effects that would be visible in the drawings. The turntable is a disk of 1/2” MDF that was cut with a router with a long compass arm.

The drive ratio with the 1 1/2” drive and the 48” diameter disk is roughly 32:1.  I carefully calibrated each motor in the software to compensate for the imprecise turntable ratio and differences in the motor drive clock crystals.

There is a single idler roller opposite the motor that supports the turntable and three hard rubber casters on the back. The 20 degree tilt on the machine insures that the turntable disk is stable and rotates freely. The friction drive roller and idler were purchased from McMaster Carr.

Gravity is very dependable! You can quote me on that!

Motors and Controllers

The drive motors for the X and Y cranks are M062-FD8103 made by Superior Electric. I purchased them from Surplus Sales of Nebraska. The larger motor driving the turntable is a Nema 34 motor. I bought that from a friend.  The controllers are Mforce drives, made by Schneider Electric

http://motion.schneider-electric.com/products/mforce_overview.html

I used two Micro-drives for the x and y motors and a Power-drive controller for the larger motor.

The communications to the motors is through RS-422 serial link.

I use a usb to RS -422 adapter from Digikey # 768-1044-ND

Software

My original code for the drawing machines were created in PureData, a data-flow language usually used for audio synthesis.  I then wrote new code using Processing and G4P user interface tools.  The software really only sends speed commands and Go and Stop commands to the motors. While the machine is drawing the computer is idle.

Speed Ratios and Sensitivity to Initial Conditions

I have been experimenting with this sort of pattern drawing in various forms for many years. I have learned what works to make interesting patterns. People ask if I know what a pattern will look like before I run a particular setting. I have a good idea of the type of image that I will get but there are often surprises that arise from small differences in the starting conditions.

One could refine the hardware so that starting states and phases could be precisely controlled but I’m not sure that would be as fun.

I have also not been interested in pre-visualizing the results using the computer. It is more interesting to see the pattern develop gradually. Observing the machine work is captivating to most people.

Although controlled digitally, the machine can be seen as an analog computer whose output is a direct graphical plot of the algorithm on a piece of paper.

 

 

 

 

 

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It’s Alive!

I’ve installed and programmed the new motor drivers.  I used two Mforce Microdrives and one Mforce Powerdrive modules from Schnieder Electric:

http://motion.schneider-electric.com/index.html

My local distributor for Schneider Electric is Olympus Controls:

http://www.olympus-controls.com/

Here is a drawing from the new Lissagraph machine:

Lissagraph Drawing X=3,Y=5, T=1

Lissagraph Drawing
X=3,Y=5, T=1

I’ll post some pictures on Saturday during the East Austin Studio Tour.
Cheers!

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