Tag Archives: digital design

Oh, OpenSCAD…

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One of things I really like about OpenSCAD is how anything I make in it is guaranteed to be manifold.  It’s a solid modeler and by manipulating, adding, and subtracting solids – I should always end up with another solid.  I exported two of the parts necessary for a Pez Powered Disc Shooter only to discover that OpenSCAD refused to compile one of the parts – because that part had some polygons with an incorrect winding order.  Mind, I had no problems exporting the part in the first place – but importing it back?  Nope.

Oh, OpenSCAD, is our love affair over so soon?

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

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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?

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? [↩]

Designing with a MakerBot

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After playing with this puzzle for a few days I’m really happy with how it turned out and I think the above improvements will make the next version a little bit better.  This reminds me of Forrest Higgs’ recent commentary on engineering with a RepRap in the design cycle.  It’s so easy to test out a new design that I don’t hesitate to whip something up, print it off, SEE and FEEL how it works and any unintended nuances of that design, and then redesign with these revelations in mind.