Magnetic coupling for dry box

prusaprinters

Magnetic filament coupling with ring magnets to get a easy access to the filament or detach the dry box from the printer.The goal was: keep it simple and easy.4 mm ptfe tube fits snuck into de hole of the magnet.The petg cap gives you a firm grip on the coupler.You need neodymium ring magnets with a proper chrome or nickel coating : 4mm inner hole, 10 mm outer diameter, 6 mm height, N48 strength. It is a common standard available magnet.I used the magnetic cap from my other project with the same ring magnet.I use the join-stop if the filament is not linked. This also has a ring magnet so that the drying box remains tightly closed. The size of this ring magnet is smaller: 6mm diameter, 2mm inner diameter, 2mm height, N50 strength. To print the join-stop I entered a pause command, the printer stops to put some blue tag in the cylinder here. After this, the printer can continue. This blue tag ensures that the filament sticks to the stop. Here this blue tag is known as poster buddies from Henkel, it is white in color instead of blue.I used 5 degr. higher temperature on petg for a good adhesion of the layers and on the bed. I also increased the extrusion factor to 1.05.Chamfer the tube a little bit on the outside to get more easy the tube in the magnetic ring. Do not cleanup the inner hole of the magnet, it will damage the magnet, it is very brittle and will start to oxidize the neodymium without the protective coating.Before you put completely the magnets in the cap/join/stop, check if they attract each other (it's sound stupid, but it will happen). The magnet should not stick out the caps, but be on the same height, so you get a strong magnetic attraction and some protection of the magnets when put together.