Impossible Screw | Direction-Changing Threads

Impossible Screw | Direction Changing Threads

At first glance, this looks like an ordinary bolt and nut; but once you start turning it, you'll quickly discover something isn't quite right.

The thing that makes this design unique is the alternating thread direction, forcing you to forget the motto “righty tighty lefty loosey”. It is a simple but fun mechanical curiosity that's become my go-to for fidgeting while working.

Whether you are an engineering enthusiast, a puzzle lover, or just somebody looking for an interesting desk toy, this print is sure to start conversations.

I designed this after wondering “What is a design that breaks the traditional rules of engineering”

Print Specs (Designed and tested on a Bambu Labs P2S)

• Multicolor 
  • ~1hr 15min print time 
  • 15.87g Bambu PLA Basic
• Single color 
  • <30 min print time 
  • 6.03g Bambu PLA Basic

Print Settings (Designed and tested on a Bambu Labs P2S)

Material: PLA recommended (Watch out for warping with other materials)

Layer Height: 0.2 mm

Nozzle Size: 0.4mm

Supports: None

AMS: Optional (for multicolor versions)

Included Plates

1. Clockwise Thread
2. Counter Clockwise Thread
3. CW + CCW Thread
4. All Parts

If you print this model, I'd love to see your make! Feel free to leave a rating, share a photo, or leave a comment with your thoughts.

Thanks for checking out my work! If you enjoy engineering puzzles, mechanical curiosities, and practical 3D prints, consider following my profile to see future designs.