Extensible Burr Set
This is a modular collection of pieces for making classic six-piece burr puzzles. It encompasses several well-known burr sets, modeled with identical dimensions to make them interchangeable. You can print one or more individual sets, a "comprehensive" set that includes 125 pieces, and/or individual combinations of pieces as necessary. Models are also included for trays that can store the pieces in a convenient display (see photos).
Six-piece burr puzzles are among the oldest and best-known interlocking puzzles in the world. A good overview of this type of puzzle is given by Rob Stegmann on his puzzle pages; Stegmann also provides 284 specific examples. In the Extensible Burr Set, each burr piece is printed with an identifying number (its "Kaenel number") stamped on the end; this numbering scheme is identical to Stegmann's, so his puzzle pages can be used as a handy reference for making puzzles out of this set.
To print, choose a set and a tolerance, download the appropriate .zip file, and print all the .stl files within. Each set is provided in three versions, with 60 micron, 75 micron, and 90 micron tolerances. 60 microns will be the tightest fit, and 90 will be quite loose. I strongly prefer the 60 micron version; I like the snug fit, especially with holey burrs. But I am printing on a Prusa i3 MK3 with PLA+ filament and 0.1mm layer height, which gives a fair amount of precision; depending on your printer, filament, and print settings, 60 microns may be too tight. I've included an example six-piece burr (e.g., example-60.zip) if you want to try out a particular setting before printing out a full set.
Some of the pieces use "snap joints" so that they can be printed without supports. After you print pieces containing snap joints, first connect all the joints before using the pieces. Align each male connector with the corresponding female connector (e.g., the male connector labeled "A" should align with the female connector with the matching "A" label on the interior, so that the "A" labels come into contact).
The joints are designed to be tight, and depending on the printer and filament used, you may need to hammer them together. If they come out too loose or too fragile, a drop of superglue on the base of the connector will make them more solid (but I've found this to be unnecessary with many filaments). The snap joint concept is discussed further in this blog post: Adventures in 3D Puzzle Printing.
Here are the specific burr sets that can be printed:
- Example - A set of just six pieces for making a typical burr puzzle (use this as a sample for testing)
- 42-Piece Burr Set - A very well-known set for making solid assemblies
- Ultimate Burr Set - 27 pieces, all distinct, that can make a range of interesting puzzles
- 42-Piece Level 5 Set - A nice set that can make a number of challenging level-5 puzzles
- Comprehensive Burr Set - Includes all of the above, and many more - a total of 125 pieces that can make nearly all named puzzles of this type
Trays are included in three sizes, 4x5, 5x6, and 6x7. I've found that larger tolerances are necessary for the trays, so I've generated them with 150 micron and 250 micron tolerances. Again, I prefer the tighter setting, as it holds the pieces firmly in place; but force may be necessary to remove them.
Also included is an OpenSCAD module that can render all of the above, or any particular subset thereof, or any others of the 837 physically distinct burr pieces. Options are included to adjust the tolerance, beveling, or the stick length of the burr pieces (the default is length 6, but you may wish to create length 8 or longer modules). There are instructions in the attached .scad file. You will need the puzzlecad library in order to use it.
Finally, the burr-tray.scad module can be used to generate trays of custom sizes or tolerances.