March 1, 2026
Description
This is Stewart Coffin's puzzle "Overdrive", the most difficult in his series of "gear puzzles". It is STC design #117. WARNING: This puzzle is difficult to assemble! Fortunately, it has a second solution which is easier to assemble.
I have modified this design slightly from that described by Coffin. He made the star ends flat, when modeled in BurrTools the ends can't be flat. This gives the final shape a different look.
Print 3 copies of the R piece and 3 copies of its mirror image (L piece). No supports are needed.
Assembly is another matter. This puzzle is related to Rosebud and requires 6-piece coordinate motion. Fortunately, it is not as difficult as Rosebud to assemble, but it is still quite challenging. I managed to do it without a jig, but it took me nearly an hour the first time. There is also a second easier assembly of the 6 pieces which goes together in halves (see the last photo).
Unlike Rosebud, this puzzle can be tricky to get apart. It is difficult to initiate the coordinate motion. It is too easy to pull too hard and have the whole thing fall apart.
I include the puzzlecad file in case you want to change the sizing or offset. The pieces I exported use: $burr_scale = 25.74; $burr_inset = 0.14; $burr_bevel = 1.0;
Printer Brand:
Prusa
Printer:
I3 MK3S
Rafts:
No
Supports:
No
Resolution:
0.2 mm
Infill:
15%
Filament: eSun PLA+ Pine Green and Fire Engine Red Category: Puzzles
License:
Creative Commons — Attribution — Noncommercial