7-segment die/dice

thingiverse

One of the key problems in making a die 'fair' (equally likely to roll each face) is that if you remove different amounts of material from the sides to form your dots (the 'pips'), then you're very slightly changing the die's center of gravity. The obvious solution is to remove the same amount from all sides, and the simplest way to do that is to make all sides identical. This is a die that, instead of having recessed pips, has a recessed 7-segment number. You fill the recess with nail polish or other paint to form the numbers (see the net diagram included with this Thing, which I grabbed from Wikimedia Commons). The number is underlined so that you can differentiate 2 from 5. I have tested multiple printed copies of this design using the simplified chi-square test described by 'Delta', and found them to be fair (or more accurately, probably-not-unfair) at α = 0.05. Print Settings Rafts: No Supports: No Resolution: 0.2 Infill: 75-90% Notes: If you print the die flat, the bottom face will become squished and unreadable. The solution is to rotate it 45° so that it is resting on only one edge. You will need a brim. Generating support is also a good idea so that the die does not wiggle while it is being printed. You should set the amount of solid plastic in all sides to be more or less equal. If I was laying down two perimeters, each 0.6 mm thick, for example, then I would want 5x 0.2 mm top layers (not 6, because there is some perimeter overlap). I highly recommend printing with a brim to prevent the die from warping. Post-Printing Fill the recess with paint and allow it to dry. Follow the cube net diagram I've attached to this Thing. I suggest making the bottom of the print the #1 face simply because the bottom of the print gets a little squished out and a simpler shape works better there as a consequence. Changelog 20 Mar 2016 Initial release. Tinkercad source document https://www.tinkercad.com/things/5Dy4I7B7V65-numbered-dice