Cubism: Using a 90 degree bit to make cubes with Shapeoko.

An exploration of interesting experiments

Getting started

So I have had in mind for a while, the idea of making cube shapes out of 1/4 inch material on the Shapeoko. Most of this came about from a combination of fiddling with a 90 degree bit and realizing that basic math says a cube is just a bunch of 90 degree angles. Maybe I could have some fun with that...

The Basics

The basic structure of the cube is a set of six identical sides cut with a 90 degree bit. Which means that each of the angles you see in this image are actually 45 degrees.

In this case, I was cutting 3 inch square sides out of sapele that was a little less than a quarter inch.

This entire design is just 6 squares in Carbide create and the 90 degree bit just traces the outline (and yes it could be simplified).

This would fold up into a blank wooden cube, which is a little boring but you can do some interesting things from this starter design.

Etching the Faces

Since our cube is currently just a set of flat surfaces, we can use Carbide Create to mill designs on each of the various faces.

The trick is, getting consistent alignment across all the faces. To this end, I created a very simple jig by bolting down a piece of 3/4 MDF to the center of my wasted board. I used a set of dowel centers (like these from Rockler http://www.rockler.com/dowel-centers) to position the holes for attaching the jig to the waste board and then drilled them out by hand. Once the MDF is attached, I then cut a 3 inch square recess in the center to hold the individual sides.

By keeping everything centered on the waste board, I can quickly set the X and Y of the machine by clicking Rapid Position in Carbide Motion and selecting the center dot in the bed (This is also the quickest way to locate the center of the waste board). Once I have my X and Y setup all I have to do is set my Z axis and Bob's your uncle.

The little circles at the corners of the jig help me get the piece back up once milling is finished. If you have a snug fit, you don't even need tape. I have also cut versions of this type of jig where I installed clamps to help hold the pieces down.

I mark the front of the jig so it's easy to swap in and out as needed. I have a small circle in sharpie on the center of my waste board to help me line things up.

Finding the Right Cube

My first test was downloading some files from the Intarwebs and tracing them with Inkscape. I chose the cube from the movie "Hellraiser" as it's  a rather iconic cube.

This one was done in 1/4 inch MDF and finished in a similar fashion to the ubiquitous Aztec Wars project that seems to be a right of passage for CNC users. Check this video for an in depth look at the finishing technique: https://youtu.be/rmqtZjZHpYM

The cubes look a bit dingy in places, but that sort of fit with the effect I was going for, sort of a recently dug up artifact.

Clear cubes

The next idea was to try a new material and see what happened. I had some acrylic laying around and so I cut a cube and used the same pattern with a diamond drag bit to etch. The whole thing is put together with Weld-On Acrylic Adhesive.

One word on the adhesive, if you get it, take the applicator bottle with needle and throw it as far away as possible. It creates a sloppy mess and fogs the glass. Use a small bristle brush and apply a thin coat to the edges. The brush has much greater control.

I also had some mirror acrylic which I etched from behind with a circuit pattern, removing the mirror portion so that light shines through. It makes for an interesting effect.

These photos are simply lit from below with a single iPhone. I am working on a base to edge light the cubes and I will post more images when I do.

The shadows they throw are really wonderful.