Combination Lock Puzzle

thingiverse

This is a six piece interlocking puzzle designed by Stewart Coffin in 1997, it is his design #128. Combination Lock is the successor to Rosebud, all six pieces are different. One would think this would make the puzzle more difficult than Rosebud, but this is not the case. Six piece coordinate motion is required to assemble it, but the coordinate motion is much easier than for Rosebud. I can assemble this puzzle without a jig. The difficult part of the assembly is because the pieces are all different, not from the coordinate motion. I like to print this puzzle in three colors. The pieces are composed of multiple parts which snap together like Legos. I include the PuzzleCAD file in case you want to change the offset or size of the pieces. Note: This puzzle requires a precise fit of both joints and pieces, which can vary with the printer and filament. You may wish to print out test pieces first to check the fit using your printer. On my printer, these joints are quite tight, I use eSUN+ PLA for added strength and have not had a one break, despite repeated snapping and unsnapping of the joints. The orientation of the joints can also significantly affect their fit. Note that the joints all face different directions. To make the puzzle shown in the photos: (1) Print "coffinCombLockPieces.stl" in black. This gives you the base of all 6 pieces. (2) Print "coffinCombLockTipsL.stl" in yellow. Six (left) tips that snap onto base parts. (3) Print "coffinCombLockTipsR.stl" in red. Six (right) tips that snap onto base parts. No support is needed. I recommend 3 perimeters for added joint strength. Now snap all the parts together, each connector is labeled to show where each goes. If the connections are loose, you can glue the parts together with superglue. I like to glue them regardless, because you do not need to take them apart to assemble the puzzle. You can use Stewart Coffin's instructions to aid assembly (warning, spoiler).