Spiral Cam Filament Clip

After watching this video from Zack Friedman about unusual printing problems, I finally got an answer to why I've had some problems with other filament clips. While there are existing alternatives that will clamp filament in multiple places so it can be kept wound tightly on its spool during storage so it doesn't break, I thought it would be interesting to borrow from the woodworking world and use a spiral cam to pinch and hold the filament. Plus, it looks cute (should I add a nose/mouth?).

These each use 3-4g of filament and take 12-20 minutes to print depending on style, settings, and how many you're printing.

Printing tips:

• 3mf files were exported from Onshape for convenience of 3-part prints.
  • If you have a multi-material printer, you will probably need to correct the slicer assignments to ensure all 3 parts print with the same extruder.
• Bridges and gaps have been designed to print at 0.2mm layer height.
• I print these with any of the 0.2mm profiles in Prusaslicer, with:
  • Increase top solid layers from 5 to 6,  to reinforce the section of the cam that grips the filament.
  • Staggered inner seams (I don't know if this adds strength, but it doesn't hurt).
• Once printed, wiggle the levers a bit until they move feely.
• Filament:
  • So far, I've had the best luck with Printed Solid Elixir.
  • PLA from various brands seems ok.
  • PETG may be a bit soft, as my tests with Printed Solid show it remains dented where the cams press against the filament.

The default version should be fine in most cases. It still takes a bit of force to clamp down but a lot of filament can be slippery and pull out even with tight clamp. Print the tight versions if you have trouble or concerns with filament slipping out (you may also find the “wide” and “very wide” lever variations help a bit here, too).

Usage:

• Feed two loops of filament through the clip, pulling the filament as tight as you need it, and clamp down the levers.
• The cam is oriented to provide the most secure clamping if you feed the filament through with the end pointing the same direction as the levers.
• When you're ready to print, simply open the levers and remove the end of the filament from the clip, leaving one loop of filament still threaded through the clip so you don't lose it.

Updates:

• 2025-11-12: even more variations
  • Four sizes of levers:
    • slim
    • default (flush with front face; formerly: wide)
    • wide (new!)
    • very wide
  • So many variations for faces, plus some arrows.
    • Face/arrows are now only on the “up” side that faces out/away from the filament. This helps as a reminder so you benefit from the a small clearance gap between back of the levers and the filament below/behind.
• 2025-11-11: more variations and a brighter disposition
  • Three sizes of levers, for those who have trouble with the original slim version.
  • Now includes versions with a smile (though my family still insists on the original because it looks a bit like Hollow Knight).
  • Change some angles and smooth some corners so it prints more cleanly and is less likely to poke vacuum bags.

Alternatives:

• Zack recommends a great little 3-part screw clip that @ZombieHedgehog has at Makerworld (sadly, not here) but after printing a couple I decided they were a bit fiddly, especially since I didn't see a version that could stay attached to the filament while it's being used (this helps prevent my cats from stealing them).
• I have been a long-time fan of K2 clips but they can be a bit sharp to use with vacuum bags if you don't get them positioned just right. I've also bent/broken filament trying to get the clip latched in (or removed from) two places to hold things tight, which is one of the things that convinced me to explore other designs.

As with most of my designs, you can find the parametric CAD source here at Onshape. And feel free to leave me messages here with questions or requests for modifications.