Magnets for 3D-printed applications
Short answer: there are two ways to put magnets in a 3D print: (1) in an open recess 0.1 – 0.2 mm larger than the magnet, secured with a drop of glue or a press fit, or (2) fully enclosed by pausing the print, inserting the magnet and continuing printing. Leave 0.4 – 0.8 mm of material between the magnet and the outside: that costs little force. The most popular sizes are Ø6 x 2, Ø8 x 3 and Ø10 x 3 mm disc magnets. Always mark the poles before installing.
Which magnet for which 3D print project?
| Application | Advice | Holding force (approx.) |
|---|---|---|
| Small lids, miniatures, model making | disc Ø5 x 2 or Ø6 x 2 mm | 0.6 – 0.7 kg |
| Boxes, enclosures, flaps | disc Ø8 x 3 or Ø10 x 3 mm | 1.4 – 1.6 kg |
| Wall holders, tool holders | disc Ø15 x 5 or Ø20 x 5 mm | 4.3 – 4.9 kg |
| Square recess or tight corner | cube or block | depends on size |
| Rotating parts, hinges | diametrical rod magnet | – |
| Screwing into the print | magnet with countersunk hole or ring magnet | depends on size |
Design tips
- Tolerances: diameter + 0.1 – 0.2 mm for a press fit, + 0.3 mm with glue. Depth = magnet thickness + 0.1 mm. Print a test piece with a few variants.
- Distance: every millimetre between two magnets costs a lot of force. 0.4 – 0.8 mm (2 – 4 layers) is a good balance. See force through plastic.
- Poles: mark the top of each magnet with a marker before installing. A reversed magnet repels.
- Pausing the print: add a pause (for example M600 or M601) at the layer above the recess. Make sure the print bed or nozzle is not hit by a protruding magnet.
- Glue: superglue for PLA and PETG, two-component epoxy for stronger joints. See how do you mount a magnet?
- Handling small magnets: use a magnet dispenser.
Temperature
PLA already softens around 55 – 60 °C, well below the 80 °C limit for standard neodymium. So the magnet is rarely the weak point. In a car in summer, though, PLA can deform and the magnet can come loose; then choose PETG or ASA.
Frequently asked questions
Should I use N52 for 3D prints?
With very small magnets it helps: a Ø3 x 2 mm N52 is more than 50% stronger than N35. With larger magnets, a slightly larger size makes more difference. See what do N35 to N52 mean?
Does the hot nozzle damage the magnet?
A brief pass over an enclosed magnet is usually not a problem, because there is a layer of plastic in between. Do not let the nozzle rest directly on the magnet.
