Category: Tips

Tips learned from experience building a MakerBot

OpenSCAD tutorial, take II

So, I’ve been working on some OpenSCAD tutorials over at the MakerBot blog.

What did you think of them?  Are they too high-falutin’ or too basic?  Are they too serious?  What would you like to learn next?  I’m probably going to cover 3D forms next.  Do you want to see more tutorials?  What other things would you like to learn besides OpenSCAD?  (That will give me a good excuse to learn it too!)

Do you want to learn OpenSCAD with me?

I’m really just learning OpenSCAD right now.  I can make some basic shapes, put things together, and whatnot.  I was thinking about putting together some super super basic tutorials that would take a user from knowing nothing about OpenSCAD to knowing as little about OpenSCAD as I do.1  Is this something you’d be interested in?

Please leave a comment and let me know.  What would you like to know about it?  What would you like to learn?

  1. Perhaps even a little less! [↩]

ReplicatorG v0023 error

“This should never happen, deltaX in addValueSegmentToPixelTable in euclidean is 0.”

And, really, this is just one of MANY such errors.

Also, Marty was kind enough to slice it up in Zaggo’s Pleasant 3D software.  He took a look at the OpenSCAD code and didn’t see anything nasty in there.

I dunno.  Do you?

OpenSCAD, ReplicatorG, why can’t we all just get along?

I need to bolt some shelving to the wall.  Yes, I know the shelves came with some hardware for doing that – but I own a 3D printer and I can design BETTER hardware.  I whipped something up in Sketchup and printed off some brackets.  Next, I needed a slight variation in order to bolt two shelving units to each other.  (Something for which their hardware wasn’t designed).

Unfortunately, ReplicatorG just puked all over itself as soon as I tried to slice the bracket.  I had been tinkering with OpenSCAD for the last week or so, so I figured I’d give that a shot.  Here’s what I tried:

  • First, I tried building the bracket up out of just rectangular boxes.  This was okay, but cumbersome.
  • Next, I tried to design a really really complex polyhedron in the shape of my bracket.  This was a nightmare.  To do it properly, you need to design your object such that you’re defining each of the triangles that make up the object.  If you get set up the triangles by putting the numbers for each corner in the wrong order, in a less-right order, or did some other benign thing, it would make a mess.
  • After chatting with Clothbot, I tried to define a cross section of my bracket as a flat image in Sketchup (again), then tried to expert it to a DXF through a plugin.  I just couldn’t manage to extrude that flat DXF into a 3D image.
  • So, I went back to Sketchup and tried to tinker with the file again, fixed it in CADSpan, exported to STL again, fixed it up with NetFabb again, and ReplicatorG still barfed it up.
  • Back to OpenSCAD (again).  This time I tried to assemble a 2D cross section of other shapes.  This didn’t work as I tried to tinker with the “linear_extrude” function.
  • THEN, finally, I tried to define a polygon (not a polyhedron) based upon the coordinates I had used originally to describe the bracket when I was attempting to build it out of triangles.  This worked to describe a flat 2D section of the bracket.  I tried the “linear_extrude” function again and it worked well.  I then punched a few holes into the bracket with some small cylinders and exported to an STL again.  It’s my understanding that OpenSCAD makes quality STL files – without holes or other cleanup required.  While that may be the case, you guessed it, ReplicatorG tossed its cookies when it saw this bracket.

So, what is it? Is it the bracket?  Sketchup and ReplicatorG?  Is it OpenSCAD?  Suggestions?

Added Flattr

The interesting thing about Flattr is that in order to be eligible to receive funds, you need to be willing to share funds.  In any case, I’ve added a Flattr button to this site as well as to my MakerBlock Thingiverse page.

Because I’m such an optimistic guy, I also just ordered an extra large wallet from Amazon. 1

  1. And tore up my ticket for tonight’s lottery.  Pretty sure I won’t be needing THAT… [↩]

The cake was a lie

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

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

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? [↩]