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Make Your Own Non-Transitive Dice at Home

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I recently discovered a YouTube channel called “Numberphile” where a documentary filmmaker Brady Haran does a series of short interviews and clips with different mathematicians and physicists about numbers.  Since my short description simply does not do this series justice – please take a few minutes and watch this recent video of theirs about how Richard Feyman defeated every government safe in Los Alamos.

Many of the videos in this series feature James Grime, a mathematician who recently invented a new kind of non-transitive dice as well as several games you can play with them.  That is, several games you can play with them and always win.  Non-transitive dice are designed in such a way that the first die will always tend to beat the second, the second will always tend to beat the third, and the third will always tend to beat the first.  Efron dice designed by American statistician Brad Efron and feature the same “circular pattern of victory” – but with four dice.  Grime dice by Numberphile star Professor James Grime feature five dice which have a similar “circular pattern of victory” with additional interesting properties.

Encouraged by Professor Grime’s infectious enthusiasm, I designed three sets of printable non-transitive dice (three non-transitive dice, four Efron dice, and five Grime dice) which you can print on your MakerBot at home – either as dice where you color in the pips or which you can print with dualstrusion.

By the way, my favorite part from any of these videos is where Professor Grime talks about how he thought up these dice in his mind, and now they occupy a real physical place in the world since he had them created.  This video includes a refrain any Thingiverse citizen is familiar with…  “I made a thing!”

(Also, please don’t use these dice for evil.  Remember that with great power, comes great responsibility.)

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New Favorite MakerBottable Home Upgrade – Switch Locks

Light Switch Lock by Yllonnoce

Light Switch Lock by Yllonnoce

I’ve got three switches in my home that pretty much need to be in the “on” position 99% of the time. The consequences of having one of these switches flipped “off” ranges from minor annoyance to zombie apocalypse. One switch goes to our front porch light, one that my laptop is usually plugged into, and the last goes to our wireless router. For a while now I had wanted to create a little cover for the light switch – basically a hollow rectangular tube that would fit over the switch and prevent someone from accidentally flipping it. While I liked the idea, I never got around to actually making it.

And then a few days ago I saw Light Switch Lock by Thingiverse citizen Yllonnoce.  The design is so simple and elegant that I knew I would be printing it immediately.  It permits temporary uses of the switch, all the while discouraging accidental usage.

As a result of someone flipping a switch I have literally lost hours of work when my laptop battery ran out of power.  Once, as a result of a laptop losing power the hard drive never started up again.  So, from now on, this is literally going to be the very first thing I install into any home I live in.  At less than 3 grams, each one would probably cost about $0.12 in plastic that will absolutely save me hours of annoyance, frustration, work, and potentially even hundreds of dollars.

A simple light switch lock like this could even be used to discouraging the accidental use of a garbage disposal, power tool, or some other appliance.  Since these switch locks work upside down, it could even save money by discouraging the accidental flipping of attic or outdoor light switches.  Not bad for a $0.12 investment.

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OpenSCAD Design Tips: How to Make a Customizable Thing

Posted by on Wednesday, January 23, 2013 in Uncategorized
You can customize this awesome cube right now!

You can customize this awesome cube right now!

Chances are you’ve been following along with the newest developments over on Thingiverse and have seen people uploading “Customizable” versions of their OpenSCAD designs.  ((For the latest information on how to make a customizable thing using the Customizer you’re going to want to check out the documentation for this Thingiverse app.  Since you have to authorize the App to be able to use it, there’s no way at the moment for me to provide a direct link to the documentation.))

If you’d like to give the Thingiverse Customizer a shot but aren’t sure where to begin, this tutorial is for you.  Before you get bogged down in the details, just know that I’ve created a “Customizer template” you can use as a starting point for creating your own customizable Thing.  I would suggest first playing with the settings in this template to see how Customizer changes the object.  Then, when you’ve gotten the hang of it, read through this tutorial on how to make a Customizable OpenSCAD file.  Finally, download and check out the template itself in your favorite text editor or OpenSCAD.  Add your own designs and see how you can make your own customizable Things!

  • Design!
    • Create your OpenSCAD thing just as you normally would.
  • Create Options
    • In order to give Thingiverse users the option to customize your designs through the Customizer App, you’ll need to create options for them.  There are three kinds of user-definable options you can include in  your OpenSCAD file: text boxes, drop down boxes, and numerical sliders.  I’ll discuss each in turn.
      1. Text Box
        1. Simple Text Box.  To add a text box, all you need to do is create a variable.  Like so:
          1. text_box = 10;
        2. Text Boxes with Explanation.  Options are very nice and well, but without an explanation they may be hard for a user to interpret.  Here’s how you would create a similar text box with an explanation:
          1. // This is the explanation text
          2. another_text_box = 10;
      2. Drop Down Box
        1. Drop Down Box of Numbers.  A drop down box can be included by simply including a “//” to comment out the space after a variable and list options like so:
          1. // This creates a drop down box of numbered options
          2. number_drop_down_box = 1; // [0,1,2,3,4,5,6,7,8,9,10]
        2. Drop Down Box of Text.  A drop down box can also include text as possible choices, like this:
          1. // This creates a drop down box of text options
          2. text_drop_down_box = “yes”; // [yes,no,maybe]
        3. Labeled Drop Down Box.  Sometimes it is useful to show the user text labels, but have a numerical value for each text label.  You can do so in this manner:
          1. // This creates a drop down box of text options with numerical values
          2. labeled_drop_down_box = 5; // [1:small, 5:medium, 10:large, 50:supersized]
      3. Numerical Slider
        1.  Once you’ve mastered the text box and the drop down box, the text slider is almost trivial.
          1. // This creates a slider with a minimum and maximum
          2. numerical_slider = 1; // [0:10]
      4. Notes
        1. Not every single variable you reference inside the Customizer start/end section will be included as an option.  If any of your variables use any mathematical operators or other variables in its value, it will not appear as an option.  This can be useful for including “hidden” options within the customizable section – by just multiplying a given variable by 1.1  For example, the following will not appear as an option:
          1. // This option will not appear
          2. hidden_option = 100*1;
        2. Neither will this:
          1. // This option will also not appear
          2. // another_hidden_option = 101;
  • Optional Libraries
  • Upload to Thingiverse
    • Once you’ve finished your OpenSCAD file, you just need to share it on Thingiverse.
    • Once it has been uploaded, just tag your Thing with the word “customizer”, publish your Thing, and you’re done!
  • Limitations
    • Right now there are a few limitations for Customizer.  They are:
      • Your Thingiverse entry can only include on OpenSCAD file.
      • Your OpenSCAD file can’t import any external OpenSCAD code, STL’s, or DXF files.
      • Your OpenSCAD code can only be compiled to a single STL file.

The MakerBot team is continually improving the Customizer, so check back with the documentation frequently so you can find out about the newest features!

  1. Such as:  “this_will_not_appear = 30* 1;” []
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How do you find out the volume inside an STL?

Posted by on Monday, January 21, 2013 in Uncategorized
A Beaker is useful for determining volume

A Beaker is useful for determining volume

A few days ago I started designing a new case for my new Polargraph drawing robot brain.   ((Joe Penniston via Compfight))  My goal was to design a simple to design, simple to assemble, and sturdy box-like case.  ((One of the reasons I am interested in a box-like case is to make sure it is easy to mount on a wall or inside a larger project box.))  However, I was stumped when it came to figuring out whether my new design conserved plastic better than the other Polargraph case design from Sandy Noble on Thingiverse.  After experimenting a little, these are the two easiest ways I found to figure out the volume within an STL file.  ((While particularly simple, I suppose if you had a really large beaker and a certain volume of water, you could print your STL file, submerge it, and compare the results.  However, this seems impractical for a lot of reasons.))

  1. AdMesh
    1. Tony Buser was kind enough to suggest an application I had never heard of before – AdMesh.  AdMesh is a free command-line tool created by AMartin1 which can provide all kinds of information about an STL file.  After fiddling around with the program a little bit, I found this command gave me the best results:
      • admesh –normal-directions –tolerance=0.01 –exact %1 >> stl-stats.txt
    2. While AdMesh worked pretty well overall, it had problems with some STL files and was unable to provide statistics.
  2. NetFabb
    1. Alternatively, NetFabb also provides some ways to find out the volume inside an STL file.
      The little button circled in red

      The little button circled in red

      1. NetFabb’s cloud-based STL repair service provides information about the repaired file including surface area, triangles, and volume.  Just submit your STL file for repair (even if it doesn’t really need it) and get back a link to your fixed file along with the relevant statistics.
      2. NetFabb’s “NetFabb Studio Basic” is a free downloadwhich also provides detailed statistics about STL files and basic mesh fixing tools.  Here’s how you do it:
        1. After you open NetFabb, “Control-O” will give you the option of selecting an STL file.
        2. Keep adding as many STL files as you would like.  It won’t matter that they are all overlapped.
        3. Click the third icon from the left, a little cube frame with a circled “i” on it.
        4. A window will pop up providing information, including volume, for each of the STL’s you have imported.
      3. I found the Studio Basic version of NetFabb’s offerings to be more useful.  The statistics seemed to be more consistent than the values from the cloud service and Studio Basic also allows you to import numerous files at once so you can compare the numbers “side by side.”

Do you have a suggestion on how better to figure out the volume in an STL?  If so, let us know in the comments!

  1. Sorry!  I couldn’t find your full name! []
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Living on the Cutting Edge with Dualstrusion

Posted by on Tuesday, January 8, 2013 in Uncategorized

Hopefully by now you’ve heard about MakerBot’s newest 3D printer, the Replicator 2X.  While 3D printing opens up a new world of possibilities, being able to print with a second plastic extruder at the same time takes it to another level entirely.  There are a lot of things that become possible with a dual extruding 3D printer that are simply not feasible by any other means.

  • Colors
    • The most obvious, and by far the simplest, use of dual extruders is to enable two color printing.  Although a single-color object could be painted, there are times when painting a particular object would require a great deal skill or be very time consuming.  While printing a plastic sushi set for my daughter I used dualstrusion to add black plastic “soy sauce” to white plastic dishes.  Sometimes, painting an object might even be impossible.  Imagine an object such as a bottle, vase, or an egg where you want to have an image or design inside.  While it might be impossible to paint inside such an object, the interior image could be printed inside the object as it is being created.
  • Dissolvable Support
    • Dual extruders allow for printing with a dissolvable support material like PVA.  Being able to print with a water soluable material means your robot could print entire mechanical devices complete with moving pieces.  PVA is still very experimental and fussy as an extruded material and at the extreme forefront of dual material printing.
  • Varying Densities
    • With two extruders it would be possible to create an entirely solid plastic object with a customizable density.  This could be used to make trick dice, a balancing toy, a toy that can’t be knocked down, a toy that can’t be stood up, or maybe a boat that is difficult to sink.
  • Mechanical Properties
    • Different extruded materials, such as ABS and PLA plastics, tend to have different physical and mechanical properties.  ABS tends to be more flexible and PLA tends to be more rigid.  A 3D printer with dualstrusion can combine the two plastics into a single object that is both flexible and rigid.
  • Simultaneous Dual Printing
    • One of the more exciting developments with dual extruder printing was a recent contribution by Thingiverse user thorstadg.  Thorstadg created a method for operating both extruders simultaneously – allowing the printer to print two objects, one with each extruder, at the same time.
  • Variable Resolution
    • Two extruders means you have two nozzles at your disposal.  However, there is no particular reason for both extruders to have the same size nozzle aperture.  With one very fine nozzle aperture and one relatively large nozzle aperture, a single object could be printed with quick printing coarse features and very high resolution features that take more time.
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Favorite Tools for Finishing

Posted by on Thursday, January 3, 2013 in Uncategorized
Favorite Tools - files, pliers, and putty knife

Favorite Tools – files, pliers, and putty knife

While at the local hardware store over the weekend I picked up a cheap set of files on impulse.  These have quickly been incorporated into my 3D printing toolbox.

  • For years I’ve been using sandpaper and a precision screwdriver set to sand and “file” away plastic.  However, I found the above set consisting of a flat metal file, triangular file, and circular file for less than $7.  Since this particular set was originally designed for sharpening metal saw blades, they make quick and easy work of plastic.  If you haven’t picked up a set like this yet, I’d highly recommend it.
  • The needle nose pliers are useful for cutting filament, handling hot plastic, clamping/fitting/or forcing small parts, and sometimes for scraping excess plastic.
  • The putty knife is useful for scraping excess small pieces of plastic off a printed object, but mainly for separating printed objects from the print bed.
  • Not pictured, I also use a variety of sandpaper.  While the metal files have been proving more versatile and durable than the sandpaper, the finer grades of sandpaper are indispensable for that really polished look.

What do you use to help a printed object look its best?

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Saving Christmas, one headband at a time

Posted by on Monday, December 31, 2012 in Uncategorized
Broken headband, fixed headband

Broken headband, fixed headband

Days before Christmas my daughter brought me her favorite headband.  With teary eyes and a quavering voice she explained that something had rolled over headband, cracking it.  The green ribbon had unraveled and the broken plastic interior had a clean break and was clearly beyond repair.  After helping her dry her eyes I told her I would see what I could do.

After about five minutes of measuring the broken pieces and some quick and dirty OpenSCAD design, I had a file ready for my Replicator1  I had my daughter sit with me as I unwrapped the ribbon from the broken plastic insert and re-wrapped it around the new printed headband insert.  I ended up having to twist and destroy one of the larger pieces of the original plastic insert to get it completely out of the tightly wrapped ribbon.

Besides learning with her about how her headband was manufactured and what could be done to repair it, we discovered how easy it would be to create an entirely new headband using another plastic insert and some ribbon.  I think my favorite part of the process came when I told her that I would have to destroy the remaining part of the original insert in order to “remake” the headband.  While a simple clean crack was enough to evoke tears, she didn’t flinch at the prospect of watching her headband further deteriorate so we could create a new one.

  1. Due to the size of the headband and its low footprint, I had to use several “mouse ears” to keep it adhered to the build platform while printing.  If you’re not designing your parts with these handy little additions, you may want to give this a shot. []
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Crayon Maker and Sharpener by CodeCreations

Posted by on Tuesday, November 13, 2012 in Uncategorized
Pouring custom crayons into printed molds!

Pouring custom crayons into printed molds!

I’ve wanted to make a MakerBotted crayon mold for about as long as I’ve owned a 3D printer.  Now this is a reality thanks to Thingiverse citizen CodeCreations.  CodeCreations1 has shared his STL’s, OpenSCAD source code, and detailed directions for making crayon molds.

CodeCreations’ method involves using a printed container into which plaster of Paris is poured.  When the plastic is removed, it leaves a plaster mold with triangular crayon “troughs.”  Then it’s a matter of melting crayons, pouring the wax into the mold, and waiting for them to cool.

Error - could not find Thing 34274.
  1. Who has one of the awesomest profile picture evar! []
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OpenSCAD Design Tips

Posted by on Thursday, November 8, 2012 in Uncategorized
Voltron, victorious

Voltron, victorious

As you may know, I’ve mentioned wanting to print a Voltron several times before.  I even tried to design one once.  Even after uploading a shoddy version, I kept on jabbering on about it.

Finally I’ve designed a printable Voltron of which I can be proud. It’s designed totally in OpenSCAD using just about every single OpenSCAD trick I know.  Additionally, I designed a hinge connector system that, I think, compliments Tony Buser’s Pin Connectors v2 system nicely. In fact, some of the connector pieces for this model are basically a Buser pin connector on one side and a hinge/joint connector on the other. The result is a snap-fit highly articulated/poseable model.

I wanted to share some of these design tricks with you over the next few posts.  Here’s a quick preview:

  • How to sketch an object with OpenSCAD
  • How to easily make regular solids – other than cubes and cylinders, like hexagons, pentagons, octagons, etc
  • How to easily make symmetrical solids
  • How to easily make irregular, but symmetrical solids

Stay tuned for these ideas!

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Jason Welsh’s Awesome Portable Folding Arduino Electronics Lab

Posted by on Tuesday, October 23, 2012 in Uncategorized
The Folding Arduino Lab by jasonwelsh

The Folding Arduino Lab by jasonwelsh

Thingiverse user Jason Welsh just shared this awesome MakerBottable Folding Arduino Lab.  This printable case is essentially a mobile electronics lab that has two drawers for holding parts and can fold up for easy storage and transport.  I suspect like many others, my electronics projects can get pretty unruly.  It would be really great to have a small case that could hold all the parts for a project in one place.  Whether you want to hold an Arduino and some parts or an Arduino with a shield on top, this folding project box was clearly well-designed to suit your purposes.  What I particularly love about this Thing is that once you’ve finalized your designs, the folding case would make a fantastic ready-to-go instant permanent project box.

If you’ve got three minutes to spare, definitely check out Jason’s video showing off the versatility of this box.

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