Updated filament sensor with jam/oversized diameter detection.

An update to my jam detecting filament sensor, now using a PINDA probe and magnets from the Prusa Mk3s. 

My original filament sensor eventually wore out when the filament wore through the switch. With the many Mk3s printers due to be upgraded to Mk3.5/3.9 there will be a bunch of PINDA sensors and magnets available, so I decided to develop a more robust sensor. 

This sensor works the same as the older version. It will detect when filament is present, and will also trigger when filament is present but jammed due to either the small kink often found at the end of spools, or oversized diameter.

• Print using a 0.4 nozzle.
• All prints are in the right orientation for printing.
• Supports needed for the lever arm (Just a small enforcer for the two pivot arms).
• Supports from the bed also worth doing for the base and the lid.
• Run a 2mm drill bit through to ensure the filament hole is the right size.
• Likewise a 3mm bit for the normal screw holes.
• The magnets are hard to insert (intentionally). Make sure you have a set of pliers ready, especially if you use glue. 

• Uses 3x m3 nuts, and 1 m3 square nut.
• A few M3 screws (2x20m, 2x10mm, 1x6mm)
• M4x6 (or maybe 8) and boat nuts to attached to 2020 extrusions.
• The 20x6x2 and 10x6x2 magnets from the Mk3s.
• A PINDA sensor
• A 10x3mm bearing (4mm wide).