Prusa i3 Mk3S extruder indicator

This little extruder indicator was inspired by others with a similar design. They did not fully meet my needs, so I made my own.

My design specification included:

• indication needs to be unique over a 360° range, i.e. no repetitive pattern (which is really helpful if you watch via a camera live stream with limited frame rate)
• needs to have a little extra thickness between the magnet and the plate, to require only one magnet (not several to gain some height)
• as PETG is notoriously hard to glue, it shall have a somewhat uneven surface to glue the magnet on
• 8mm round shape in the middle, to adjust a 8mm magnet exactly in the center
• 42mm diameter to fit to the size of a NMEA17 stepper motor
• completely round and even on the outside diameter to avoid anything getting caught
• as little mass as possible at the outside, to keep rotation inertia low
  It may not be as aesthetically pleasing as other designs, but it is very functional and does exactly the job for me.

Hope you like it. Happy printing and please post a picture if you use it.

Print instructions

Print in the color and material of your choice (PLA is much easier to glue in the next step)

Glue a 8mm round neodymium magnet on the 8mm round part on the backside. With PLA you can use superglue. With PETG use glue that you have found suitable for that material. A glue that grips into the little relief on that surface should work best.

Make sure the glue is completely dry and the magnet does not come loose easily

Snap the magnet to the axis of your extruder stepper motor

Have fun watching and be amazed how hard your extruder works going back and forth