Picking parametric fingers

This post is intended as a set of “guidelines” to creating a parametric design in OpenSCAD.

Last Sunday afternoon was spent working out a parametric design for printable prosthetic fingers.  Using the OpenSCAD function “hull” it’s relatively easy to crank out a nifty organic appearing design.  Admittedly, you have to have a working knowledge the basic union/difference/intersection function first.  However, once you do it’s really quite easy.

The feature of the design I’m most proud of is the “nail” part of the finger tip.  I designed the “nail” by using the OpenSCAD function “intersection()” on two cylinders.  The little “nubs”1 consist of a small cube, rotated so a corner is pointed straight up combined, with an identically situated cube rotated slightly.

When I’m designing something to be parametric, I usually don’t really start out designing it that way.  I first strive to create a form in OpenSCAD that resembles closely the thing I wish to design.  Then, I poke through the design code looking for those elements that are related to the design aspects I’m interested in changing based on parameters.  Once located, I replace those parts of the design code with variables that can be specified when the module is called.  I realize this is kind of a “high level” description of my design process for parametric things, but it’s still the best description.

Since last Sunday I’ve really done a lot with the design.  Some simplifying and a lot of improvements.  In the next post I’ll go over these features.  I’m really excited to show these off.  :)

1. Meant to give the finger grip and texture [↩]