Introduction: No-glue Magnetic Joint or Box Lid Catch in Lasercut Sheet

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Not many steps to this one - just an easy way to make a semi-permanent joint in lasercut acrylic or wood. This would be ideal to hold a lid onto a lasercut box, for instance. The aim is to embed rare earth magnets inside each piece you want to join together, and because most (cheap) laser cutters make slightly chamfered cuts, you can do this without glue. The holes I cut on my laser cutter are always slightly larger on the top face of the sheet material than on the bottom face (when placed in the laser cutter).

You will need:

  • 5mm diameter rare earth / neodymium magnets
  • Acrylic or plywood sheet that can be lasercut - 3-6mm thickness will work best
  • Lasercutter
  • 2D or 3D CAD software (I use SketchUp to make designs for my laser cutter)

Determine the size of the holes you need to cut in the sheet material to hold the magnets

1:15 In your CAD software, design a test piece like the one shown at this point in the video, with a few circular holes of different diameters. The each hole should vary from the stated diameter of your magnets by a few fractions of a millimetre. Cut that piece on your laser cutter, using the same cut settings as you'll use on whichever project you're working on.

1:45 Try pushing a magnet into each of the test holes. Find one that's big enough for you to push the magnet in all the way, but small enough so that the chamfered edges hold it in place. Referring to your CAD design, make a note of the diameter of that hole. If you don't find a suitable hole, design another test piece with larger / smaller holes.

Add the holes to your CAD project

0:31 In your CAD software, add holes of the diameter you found using the test piece, to each face you want to join together. The holes should be positioned so that they line up when your semi-permanent joint is assembled. The most important thing to remember when cutting your sheet material is that the lower face of the sheet, when placed in the laser cutter, should be the face of the joint. That's because the chamfered holes need to have their smallest opening on the face of the joint, to stop the magnets being pulled out.