Making the Perpetual Calendar Blocks

The Perpetual Calendar Blocks (Purchase a set here) are based on a ratio of sizes such that the blocks fit together neatly.

The months are 2 units square and 12 units long. The weekdays are 3 units square and 12 units long. The numbered blocks are cubes 6 units on each side. For my set I used 3/8” as my unit. This makes the months 3/4”x3/4”x4 1/2”, the days 1 1/8”x1 1/8”x4 1/2”, and the numbers 2 1/4” on each dimension.

After a lot of experimenting, I learned that the key to making the set look good is to have very precise dimensions. I achieved this by initially cutting the blocks 1/16” to 3/32” oversize then sanding them down on a drum sander. I checked the dimension with a caliper after each pass on the sander.

It took some trial and error to determine the numbering scheme for the number blocks so that I could form every number from 1 to 31. One block has 0, 1, 2, 3, 4, and 5 on its 6 sides. The other block has 0, 1, 2, 7, 8, and 9 on its 6 sides. The 9 also serves as a 6 for the numbers 06, 16, and 26.

After carefully creating the blocks, I need a way to hold them in position for engraving. I created a jig to hold the blocks.

I made the box with the MakerCase website. It’s a great website for creating all sorts of boxes. I highly recommend it.

The Lightburn file for the blocks is available here. The box is available here. I cut the box from 1/16”. The Lightburn settings work for my 60W OMTech laser; you may have to vary them for your laser.

The blocks are in the Lightburn file in layers. You will have to output and show each layer in the Cuts/Layers window one at a time. Because there are 4 engravings on the months and days blocks and 6 sides on the numbers, there are 6 layers total. By setting the layers to cut and show in the Cuts/Layers Lightburn window, you can engrave all the blocks in 6 steps.