18mm sensor mount for Prusa MK3s extruder (eg. LJC18A3-H-Z/BX)

Despite capacitive sensor is probably not the best idea for MK3s extruder due to weight and lower precision, my personal experiences are good. Mine is LJC18A3-H-Z/BX. I like it as sensor do not touches bed (unlike bltouch) and will trigger on all materials include glass (unlike inductive/PINDA). I was just missing mount for my custom-made printer with Prusa mk3s extruder.

Simpliest PINDA to 18mm reductors were not good enougn as design was too "jumpy" and gets loose over time. It is because 18mm dia sensor is quite long and works like lever. So I created new design with proper solid mounting.

Of course design works with any 18mm sensor with similar design.

You just need to sacrifice existing extruder-body component to remove PINDA clamp. Same screw will be then reuse for modified extruder-cover mounting. You can also print my modified extruder-body which is pre-prepated.

Modified extruder-cover has exactly the same mounting as original. Just instal sensor as per picture. Do not forget to print and insert spacer "sensor_insert.stl" between clamps so nuts can be properly tightened. I believe that picures are self-explanatory.

Extruder-cover is based on latest Prusa R5 design which prevents melting.

Tips for precision improvements of capacitive sensors: Set sensitivity to lowest as possible, place sensor to almost same Z as nozzle (when nozzle touches bed, sensor should be as high as thickness of credit card). Then adjust desired Z home position via Marlin menu in display (Control->Movement->Z Offset). Also bed temperature may change triggering point little bit - recommended to do bed leveling on hot bed (via initial g-code in slicer) and recalibrate in case of print of materials which require siginificantly different bed temperature setting (eg. PLA vs ABS - difference may be up to 0.1mm). As long these factors are keep on mind, repeability and precision is pretty fair and bed leveling works pretty good on all surfaces.

Print instructions

Printer Brand: Prusa

Printer: I3 MK3S

Rafts: No

Supports: Yes

Resolution: 0.2

Infill: 20%

Filament: [ DevilDesign black PETG ]

Notes:

Use PETG as Prusa standard, infill 20% is ok just suggest add extra perimeters (eg. 4) to increase durability.

Also recommended to add few supports to overhangs. Easy to remove after print.