Archive for the ‘DIY’ Category

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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New Drawing Machine Coming

I’m working on a new Drawing machine. Lissagraph 2
Though similar to the last machine, it will be larger and a free standing machine that draws on paper up to 4 feet in diameter.

I’ll have pictures of the work in progress real soon.

Cheers.

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Six Pack Tesla Coil

Introducing the 6-Pack Tesla Coil

Image of a small Tesla coil

I was invited  (and encouraged) to write an article for Make Magazine for an introductory Tesla coil project. This one is a simple spark gap coil using beer bottles for a tank capacitor and a small Neon Sign Transformer (NST).  It doesn’t play music it just makes loud sparky noises.

The article is meant to teach the basic skills and practices to build and tune a Tesla coil using common materials that are readily available. I wanted to provide enough detail and instruction so that a beginner would be successful.  The coil is made to be modular so that the maker can experiment easily and change out bits as they learn how to get bigger sparks out of their coil.  I hope to post a few improvements after the article gets out so folks who wish to, can get a bit more spark length out of their coil.

The print article will be 18 pages and will be in issue 35 of Make Magazine. The web version of the article includes more detailed instructions and is available here.

I hope a few people actually try to build the coil.  The interns at Make built theirs and were thrilled when they got it debugged and tuned up. Here’s a picture of their coil:

Test coil built by Make Magazine staffPhoto by Sean Ragan

Note that they had to add a bottle to tune the coil so its even better than a Six-Pack!

Thanks to Sean, Keith and the rest of the Staff at Make for the opportunity to write an article.  I’m looking forward to the next, maybe simpler, article.  Thanks to Steve Ward for proof reading the article and making sure I got the technical stuff right.

A special thanks to Bart Anderson for his fantastic JavaTC program and his website. Its a great resource for coilers!

Cheers,
Craig

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New Drawing Machine

Hello all
It’s been ages since I posted anything. This is mostly because I was not able to get much time in the shop over the last few months.  I’ll try to keep up with the blog a bit better.

I built this stepper motor driven drawing machine based on an idea from a toy from the 1920’s. The Toy is called the “HOOT-NANNY”   Yes, really, that’s it’s name.

I scaled it up to create complex guilloché patterns on paper.

Guilloché is the word used to describe intricate repetitive patterns often used in security printing and fine metal working. The machine uses three micro-step motors that are controlled by a program written in PureData. Careful control of the motor speed ratios and positioning of the pen arms results in complex patterns. Some of the best patterns are the result of setting the speeds very near but not quite on specific harmonic relationships. The pen traces a Lissajous curve and the paper rotates beneath the pen, thus tracing out the complex pattern.
The patterns take from 10 minutes to and hour to create.

Puredata is not really intended for motion control but I found it really easy to manipulate the ascii to create the strings for the motors.  If I tried to do this in C or Python It would taken much longer to program.  In puredata sliders and buttons are a snap.  Opening two serial ports turned out to be easy as well.

Special thanks to Olympus controls in Austin.

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Got it done!

Thanks to the help of some friends I was able to deliver a working artillery game to the Dorkbot event last Friday night.

Amazingly to me, the code came together Friday morning with lights a-blinkin’ and speakers a-beepin’.  The machine came to life at about noon on Friday.  I think the game was well received by all the people who took a try.  One young fellow pictured here, really got into it!

Special thanks to Angelo Fancello and Oliver Greaves for late night assistance.  And thanks to my wife, Sally for her help and patience with the crazy schedule I’ve been keeping.

I’ll post the details here soon, including schematics and “code” (it ain’t pretty but it worked!).

Thanks to RadioShack for the opportunity to produce something fun with RadioShack.

Craig

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HD 3d Camera

Here are some photos of a full HD Stereo video camera I built using two Kodak Zi8 pocket cameras.  I built the case out of birch plywood and maple.  I choose the Kodak Zi8 camera because there was an optional remote control.  The cameras are linked to the remote with plastic fiber optics embedded in the frame.  This let me control both cameras with fairly accurate timing.

The width of the cameras was about 62 mm which is just about the right interocular distance.  I ended up with a final Interocular distance of about 65mm.  The cameras are quickly removable by lifting the hinged wood clamp.  Magnets are used to hold the clamp in place.  Rubber pads contact the camera at three points to get repeatable accurate positioning.  The pockets for the cameras were made carefully to get a nice close fit so that the stereo images would be as closely aligned as possible.  The two camera views are parallel and do not “toed-in” or converging. The tripod is attached at a point centered between the lenses using a 1/4-20 t-nut in the base.
We are using a free Windows program called stereo movie maker, which you can see here:
http://stereo.jpn.org/eng/stvmkr/

Here is a great primer on shooting 3d video from Tim Dashwood.

Sally and I presented the camera and some example videos at Dorkbot Austin on Monday January 24th at the at UT.  I built the camera for a project Sally is working on at the TACC visualization lab at UT.  http://www.tacc.utexas.edu/ The folks there have put together some fantastic visualization hardware and tools.  Check it out.  I’ll be adding a post soon with details on how I created the anaglyphic 3d video for the talk.

Here is a link to the video:http://www.youtube.com/watch?v=_UxQPMykqPo

See  http://www.dorkbotaustin.org for details. Don’t miss the next Dorkbot!

Craig

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Harmonograph for the 2010 East Austin Studio Tour

Thanks to everyone who dropped by at our studio for the East Austin Studio Tour last month.  We had a nice stream of visitors at our gallery space where Sally and I had some of our art work displayed.  We sold a few pieces as well.

At the last minute I decided to build a harmonograph in the shop since I didn’t have another project ready to show.  After a few years of EAST,  people come by and expect to see something interesting.  On the Thursday before the first weekend, I started building a rather complex harmonograph.  I had an idea for a linkage scheme to combine the motions from two pairs of pendulums.  The whole thing would fit nicely on my big worktable.

I did not have enough time to build all the degrees of freedom into the linkage so I hacked away and ended up with a complex gadget that had too much friction and didn’t work!  On Saturday morning I started to quickly  simplify the thing.

My friend John drove out from Houston for the weekend.  He arrived at about 10:30 am and joined me in re-working the harmonograph into something that worked fairly well.  Lots of people came through and spent some time watching the drawings form.  It was hypnotizing.  Some folks hung out for over an hour and took turns creating patterns.  We added a third pendulum which moved the paper in one axis and that’s the way it stayed through EAST.  After the second weekend of EAST I modified the harmonograph again and added a fourth pendulum so the paper was driven by two pendulums and the pen by two more.  This is what you can see in the YouTube video.   I hope to design a nice portable harmonograph so I can have one to demonstrate at schools and such.  A few people asked if I would build them one.  I’ll ponder that idea.

Here are a few results from the harmonograph:

( Click on the images to see them big.)

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