Reuleaux triangle

If you think this looks like just another useless desk, toy, you are sooo wrong! It’s actually a sample to demonstrate  my plastic cutting capabilities. I was perusing Thingiverse looking for inspiration, and found this version, which at number 1082 appears to be a pretty early thing.

I liked the Reuleaux triangle because it incorporates some interesting geometrical concepts. Here’s a diagram to illustrate:

It just so happens that this shape rolls around nicely inside an appropriately sized square, as the following animated gif illustrates:

It’s a  principle which has actually been utilized to drill square holes. Click here to see the Wikipedia entry. Reuleaux, in spite of his French-sounding name, was actually a German engineer who did pioneering work in kinematics.

Here’s one last macro shot of my sample, showing the chamfer cut on the recesses where the nuts fit:

The nuts which fit in these recesses are 10-24 thread size, and are 3/8 of an inch across. Those toolmarks on the bottom are from an eighth inch diameter bit.

The plan is to put promotional engraving on these, check back for examples!


stuff you can’t do with a laser

Lasers work well for cutting plastics- they’re fast and accurate, and leave a nice shiny edge, which is usually a good thing. There are however some drawbacks. Those nice looking shiny edges can develop cracks when glued, because they have stress “baked in” by the laser.

And you also can’t  add 3D features like this nut pocket:

With a router you can also add bevels to the edges of a part like this:

The part  in the picture above is made from extruded acrylic. It doesn’t machine quite as nicely as the cast acrylic in the first two pictures, but with good sharp tools and appropriate cutting strategies it can be cut quite well.

If you have parts that were already cut on a laser and need some additional features added to  them I can definitely help.