Adam Harris
FabAcademy Projects

February 5th 2014:    CAD Design Software

The discussion today focused on Design software for both 2D and 3D designs. Neil showed some examples of the types of features too look for in a CAD package and demonstrated some of the really neat software he ad his students have written.

Homework:

• Test out a bunch of the CAD packages mentioned in class
• Draw a 2D and 3D CAD drawing of our final project

My design files for this week are available for download here.

In the past, I had tried many of the commonly used CAD packages and am well aware of their pros and cons. Most of them I did not like due to the user interface. I find that some tools are intuitive while others are really not. I've listed below my thoughts on the tools I tested:

Software I like the most:

• Moment of Inspiration (MOI): This is a software that wasn't lisited on the FabLab page, but I came across it years ago when it was first starting and found the program very easy to use and intuitive. It exports DXF and STL formats among other 3D modeling formats. I have lost touch with it (now that it costs $300) but I liked it very much.


• OpenSCAD: I like this a lot! You can program your 3D objects and use boolean operations on 3D shapes. I've used it in the past for 3D printing stuff and really enjoyed it.


• SketchUp: Is my favorite in that it is scriptable, free, and works on many platforms (with the help of PlayOnLinux or Wine). I am still not an expert at it, but I find the controls very intuitive.


• Kokopelli: I could not get this working on my computers. The error states " importing koko.glcanvas Error: libfab not found "  Which is odd since "libfab" is a folder in the kokopelli directory.  To fix this, I searched around until I found a solution that worked. It turns out there there is an extra step required in some cases.  I had to install PyOpenGL from the 'pip' program as root before running kokopelli.   $ sudo pip install PyOpenGL
  
  Then I could run finally kokopelli from a terminal in that directory.:  $ ./kokopelli  I got  it running, however I didn't know much what to do with it. It looks like it uses python and a custom visual grammar, but I couldn't find any guides on how to use it.


• Antimony I couldn't get this working on my computer either. After making and what-not I kept getting the "PySide import failed" error. I am not sure how to fix this either. Using $sudo pip install PySide  does NOT work!!!  and neither does: $sudo apt-get install python3-pyside


• FabServer / Fab Modules: The Fab Modules are an awesome set of scripts! I love that this tool exists! It solves so many problems!  Fabserver is a bit tricky to use for me at this point. I will have to read up on it more before I am able to do much with it. I want to add to it!

The following are software packages I did not like very much, but I can see where they fit in in the zoology.

• Rhino: This software is great for all sorts of projects from game design to machining. Ti is very polished and fairly intuitive. There are also plugins you can install (which is a must for CAD in my opinion) The biggest drawback is that it is not completely free and there is no linux version.
  


• Blender: You have to have a PhD in Blender to be able to use this software, I have tried multiple times to no avail. You cannot just pick it up and use it. Otherwise it is great because it supports many formats, is basically a game engine and has tons of plugins. It is also cross platform.


• FreeCAD: FreeCAD has been described as a free AutoCAD. It is free and open source. It has a Python API so scripts can easily be written. The software is overall fairly intuitive and it isn't a chore to use. It is cross platform, supporting any machine I might be working on at the time. The bad news is that I have experienced bugs in the past, especially when trying to install in linux.


• Art of Illusion: This software seems to geared more towards rendering. I have used it once a few years ago for something tangentially related to my MS Thesis project. I didn't like it that much for no particular reason other than it reminded me of M$ Paint.


• TinkerCAD: This is an online editor. That's the main problem I have. I personally dislike creating IP in the cloud ever since Thingiverse changed their licensing a while back. Any online service usually has it in their terms of agreement that they can change the terms at any time, and that might include owning your IP... I am always wary now.


• 123D: Same as with TinkerCAD. I don't trust other people who can change the rules and have copies of your work.


• Solidworks: This software is great, but takes a few days/weeks to get the hang of. It is not free, but it is a professional-grade software. Really powerful. I made a quadcopter design in this package last summer.


• Creo: This used to be called "Pro-E" and there is even a student version of this. Years ago I used Pro-E to make an engine that runs on compressed air. I found it more intuitive than Solidworks but still it has its own eccentricities.

   I drew my design in Inkscape and then imported it into Sketchup and made a quick 3D render. I chose Inkscape because of cross platform ability, and since I will be laser cutting the design, that's the software I would need anyway. I looked around for some examples of "Living Hinge" and "kerf bending" samples online to see if I could find a calculator or something to give me an idea of how to do that. I couldn't find anything like that, so I found samples of actual items other people have made on Thingiverse, and used those as a guide. I looked at material thickness and the radius of the bend of three main versions of "living hinges." I found that it seems it is a lot of trial and error to get a good kerf bend.

 Here's what I came up with for Inkscape 

And here is the Sketchup 3D version. You can see it is meant to be a 2-ply design. high tensile wire will run into the thumb, index and middle finger. The ring and pinky fingers will move together as in a human hand so they will only use a single servo for the pair.  The servos here are actual size and so is the battery pack.  I assume the circuit to fit on top of the battery pack.  I may add joints in the palm to move with either the ring/pinky pair or the thumb. This will allow the hand itself to curve around objects for a better grip.