How to Embed Magnets in 3D Prints
Model a pocket about 0.1 to 0.3 mm larger than the magnet and press or glue it in, or pause the print at the layer above the pocket, drop the magnet in and let the printer seal it over. Popular sizes are 6 × 2 mm, 6 × 3 mm, 1/4 × 1/8 Inch and 10 × 2 mm discs. Mark the polarity before you start so every part attaches the right way round.
Method 1: Press-Fit or Glued Pockets
- Size the pocket. Make it 0.1 to 0.3 mm wider than the magnet; most FDM printers print holes slightly small. Make it about 0.1 to 0.2 mm deeper than the magnet so it sits flush. See pocket clearance for 3D prints for press-fit, glued and resin values.
- Print a test coupon with a few pocket sizes and keep the one that fits snugly.
- Check polarity against the matching part before inserting (see below).
- Press the magnet in with a flat tool or a bench vise. Don’t hammer it: neodymium is brittle and can chip.
- Add glue for permanent parts. A drop of super glue or epoxy keeps magnets from pulling out over time. See adhesives for magnets.
Method 2: Captive (Print-In) Magnets
- Design a closed pocket about 0.2 mm taller and 0.2 mm wider than the magnet, with 2 to 4 layers of plastic above it.
- Add a pause in your slicer (“pause at height” or an M601 command) at the first layer that covers the pocket.
- Drop the magnets in when the printer pauses, checking polarity. A tiny dab of glue stops a magnet from jumping toward a hardened-steel nozzle or steel screws in the print head.
- Resume. The printer bridges over the pocket and seals the magnet in.
Keep the Skin Thin
Every layer between the magnet and its partner is an air gap. For a 6 × 2 mm N52 magnet against steel, a 0.4 mm skin leaves about 45% of the pull and a 1 mm skin about 21%, by our estimates. Thinner skin, or a thicker magnet, holds better.
Best Magnet Sizes for 3D Printing
| Magnet | Pull force | Good for |
|---|---|---|
| 6 × 2 mm Disc, N52 | 1.6 lb | Gridfinity bins and baseplates, lids |
| 6 × 3 mm Disc, N42 | 2.0 lb | Thicker walls, a little more reach |
| 1/4 × 1/8 Inch Disc, N52 | 2.9 lb | Boxes, enclosures, tool holders |
| 8 × 2 mm Disc, N52 | 2.4 lb | Wider, flatter pockets |
| 10 × 2 mm Disc, N52 | 3.3 lb | Panels, covers, mounts |
| 3 × 3 mm Cylinder, N42 | 0.6 lb | Small hinges, articulated models |
| 1/2 × 1/8 Inch Disc, N52 | 8.15 lb | Wall mounts, heavier lids |
Getting Polarity Right Every Time
Keep your magnets in one stack and, as you slide each one off the top, mark its top face with a marker. Every marked face has the same pole. Decide once, such as “marked face out on bins, unmarked face out on baseplates”, and write it on your design. A Pole Detector helps when you’re unsure.
Heat and Safety
PLA softens around 60 °C, and standard magnets are rated to 80 °C (176 °F), so prints left in a hot car can loosen or weaken. See can 3D printer heat damage magnets? Small magnets are a serious hazard if swallowed: seal them in fully if children might handle the part.