Mechatronics Zone

Alibre now offers inventors, hobbyists, and entrepreneurs Alibre Design PE, a $99 version of its 3-D CAD tools. I know some individual inventors, entrepreneurs, students, and high-end hobbyists use 3-D CAD tools. And anyone who requires CNC machining or rapid prototypes must use a 3-D CAD tool. But are such tools right for students and people on a small “start-up” budget of money and time? The Alibre Design PE looks attractive at under $100, but is it really worth the price? About two years ago my son and I discussed building some “Skinner boxes” for his animal-behavior class. He wanted to have students feed mice small amounts of food when a mouse pressed a lever or responded to an LED. Commercial Skinner boxes exist, but the ones he looked at cost too much or involved shoddy construction.

We devised a way to have a solenoid dispense powdered food and decided to create a dimensioned drawing for our prototype. (We planned to build a dozen boxes.) I downloaded a trial version of Alibre and found it maddeningly difficult to learn to use even when a tech-support person gave me help over the phone. I dropped back to using graph paper and created a 4X 2-D drawing in about an hour. I did not try to use Alibre again. We machined the needed Nylon and aluminum pieces based on the drawings and had no problems.

A few month ago I wanted to create an illustration for this column and thought the free Google SketchUp software might do the job. The drawing required some tubing connected to a block of material with a few holes drilled in it. I could create a freehand drawing, but a SketchUp drawing would make it look more “professional” and I could give SketchUp a try. I gave up. SketchUp wouldn’t let me easily create the tubing. Instead, I had to create a cylinder, create an internal concentric cylinder, and then “remove” the material from the internal concentric cylinder to create the tubing. Why not simply specify a tube with a given length, diameter, and wall thickness? After all, when I need tubing for a project I don’t buy solid rod and drill it out.

Is it just me, or do some mechanical design tools seem counter intuitive and more difficult than necessary to learn to use? –Jon Titus