Making A Turner's Cube

I saw these on the CNC Cookbook and CNC Zone, and decided that I had to try making one too. I had just started to learn SolidWorks and this was a great first project.

SolidWorks Design

I knew I was going to start with a 2" cube and that I wanted the smaller cubes to each be half an inch smaller than the larger cube - i.e. the four cubes will be 2", 1.5", 1", and .5" per side. The inside cube dimensions are determined by the counterbore depths, and how much of each edge is revealed is determined by the counterbore diameter. I got the idea of using an overlap parameter from Robert Warfield of the CNC Cookbook.

You can see the three calculated diameters based on the scale factor in the left hand window pane. I then rounded the calculated values for the final diameters for the three counterbores (Cut-Extrude1 to 3). This modeled the counterbores on the front face, which then had to be patterned on to the other five faces of the cube. That was done using the two circular pattern (CirPattern1, 2) features. The first circular patteren copied the counterbores on to the sides and the back, and the second circular pattern copied the counterbores on to the top and bottom (the two circular patterns are based on two perpindicular axies).

Here's a screen capture of my SolidWorks design file:

Click HERE to download my SolidWorks design file.

Lathe Face Plate

The CNC lathe I use has both a 4-jaw chuck and a face plate. However, both of these are huge, heavy, and great for large parts; but don't work so well for small delicate parts like a Turners Cube. I made my own face plate for some small square parts in the past and it worked perfectly for this project as well.

The face plate is composed of two parts; a stem and a top plate.

These get bolted together:

The T-slots fit the same T-nuts as the shop milling machines.

The brass plug helps center some parts (but it wasn't used here).

The face plate is clamped in the 3-jaw chuck and two pieces of right angle Aluminum act as a reference corner. A dial test indicator and the four adjustment screws on the chuck are used to center it.

Machining

Square a 2" cube of 7075 Aluminum. Drill 23/64" and ream a 3/8" hole through each axis. Then put a 5/8" diameter .730" deep counterbore in each face.

First counterbore:

Third counterbore:

Finished cube:

Make another!