Category Archives: Design

Design tips for creating 3D digital models for printing on a MakerBot

The cake was a lie

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So, I’m just learning OpenSCAD when Tony Buser leaves this comment:

This should be in the next version I believe, see: http://gitorious.org/openscad/openscad/commit/d479fca855688c92f4a9f72f4ec18d655c3b351d

Also, you can set variables on the command line like this:
http://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Using_OpenSCAD_in_a_command_line_environment So you could set a variable to a random value in a shell script too.

Unfortunately, since variables aren’t really variable in openscad, it’s often easier to write code in another language that writes out openscad code. :(

Okay, what the hell.  “Variables aren’t really variables”?  What does that mean?  Yes, yes, OpenSCAD is written using a keyboard, but not really a keyboard.  T, are you just messing with me or what?  How the heck am I supposed to learn this language with this kind of nonsense?!

Amusingly, Tony is the second person to mention that sometimes it’s easier to use another language to write OpenSCAD.  Kidding aside, I kinda get that.  I use PHP to write custom javascript and MySQL all the time, since I sometimes have need for more dynamic-ness than those languages can accommodate. 1

  1. And, as we all know, I’m ever so dynamic [↩]

OpenSCAD and randomness

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A quick google search tells me that OpenSCAD doesn’t have a random number generator.  That’s a bit of a bummer.  I was just thinking how cool it would be to have an OpenSCAD file that would give you little variations on itself every time you generated an STL.  I’m thinking snowflakes, giant fingerprints, and other things that have a little bit of chance and chaos built in.

Or, perhaps some kind of Mad Libs-esque system where you tell it to create an alien or monster figure and you get a random number of eyes, heads, noses, arms, legs, and tails.

Now, I figure with CloudSCAD it wouldn’t be terribly difficult to add a little bit of javascript that can include a random number with given parameters…  So, it’s at least possible.

Playing with OpenSCAD / CloudSCAD

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Inspired by MaskedRetriever‘s last few Thingiverse blog posts on OpenSCAD I tried it out again.  Well, to be fair, I’ve been trying Tony Buser’s CloudSCAD.  I’ll get around to actually installing OpenSCAD, but playing with CloudSCAD is so dang easy.  It is limited by the power1 of my netbook.

I have always enjoyed the ease and immediacy of Sketchup.  Complex objects and forms are easy.  Amusingly, sometimes the smaller simpler bits can be more difficult to tame. 2  But, CloudSCAD does appeal to my programmer/hacker nature.

In any case, I’ve managed to conjure simple forms – spheres, cubes, boxes, cylinders, and cones.  I can assemble and subtract forms from one another.  But, it appears that more complex or irregular polygons are more difficult.

What CAD program do you use and why?

  1. Or, lack thereof [↩]
  2. Wouldn’t you agree Chris? [↩]

Printable Voltron!

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Leonardo Voltron!

Leonardo Voltron!

I’ve mentioned wanting to print a Voltron several times before.  It was Tony Buser who mentioned modifying the Leonardo Robot by jrombousky.

Well, I finally got around to designing it!  All you have to do is print up the parts from Jrombousky’s Leonardo Robot and then this single plate of parts.  Swap out the bits, paint to suit (or print in the color of your choice).

Yay!

It was called a “Tracer Gun”

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Tracer Gun from collect-antiques.net

Tracer Gun from collect-antiques.net

Despite my best efforts I could not locate an image on the interwebs for the kind of disc shooter I remember playing with as a kid.   Finally after much googling, I found a picture and the actual name of the type of toy.   Apparently they were known as “Tracer Guns” and were produced circa the 1960’s through 1990’s.  (Image of a Tracer Gun at right from collect-antiques.net).  Whenever I searched for these online I only found references to larger disc guns that shot larger foam discs from cylinder mounted on top.

A variation I had not seen as a kid, but desperately wanted, was disc shooter that had a removable and re-loadable clip.  In the pictures to the right you’ll see a grove about halfway down the barrel, just above a protuberance.  That protuberance would house about 20-25 discs depending upon the gun you had.  In order to load/reload the gun you would have to slip each disc under the firing pin one at a time.

Once I discovered the name of this type of toy, Wikipedia filled in the rest.  They had some pictures of a tracer gun which had been taken apart to expose the insides.  The best part is the gun depicted has a clip loading mechanism!

Having taken apart the non-clip version as a kid, I recall it having a similar metal spring as a source of power. 1  I believe the rubber band on the trigger is merely to keep it in place.  The protuberance on the non-clip version and the clip on the clip version of the toys both contain springs for advancing the next disc into place.

To be clear, I am not looking to duplicate, copy, or replicate this toy.  I don’t want that toy.  Rather, I would love to print a toy of my own, or a collaborative, design that will shoot harmless plastic discs.

Tracer Gun, clip removed - from Wikipedia

Tracer Gun, clip removed – from Wikipedia

Tracer Gun, exposed - from Wikipedia

Tracer Gun, exposed – from Wikipedia

  1. They were quite breakable, unfortunately. [↩]

What kind of crayon molds would you like to see?

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I like the idea of making a crayon mold with my MakerBot.  I even have a draft design sitting on my hard drive.  However, what’s a good shape for a crayon mold?  Triangular crayons, square crayons, fat crayons, thin crayons, flat crayons, smiley face crayons, Christmas crayons, Halloween crayons, Valentine’s Day crayons, Easter egg crayons…

If you could have any1 shape crayon, what shape would you choose?

  1. PG-13 [↩]

Bearings

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I’m working on designs for MakerBot printable bearings.  The proof of concept tests so far have been very promising.  I’ve printed one that’s a little larger than a 608 bearing and turns quite well.

The secret is that I’m not using printed ball bearings, just the printed casing.  :)

My final proof of this part will be to install it in place of one of the bearings holding the Z axis in place.