Probe Arm And Endstop Switch Feet For OpenFlexure Delta Microscope

Note

The probe arm assembly has been replaced with the much more accurate Mk 2 design. The endstops are still good, however. 

Overview

These are for turning an OpenFlexure Delta Microscope Stage into a very small 3-axis CNC device. Basically you can move whatever is clamped to the stage into a static probe and poke things with it.

The replacement feet for the delta stage contain a microswitch that is actuated when the stage drivers reach their lowest position, allowing standard GRBL firmware to implement endstops. A portable Python GUI that drives the GRBL hardware (and GRBL settings) can be found at https://github.com/VikOlliver/RepRapMicron where my successor to this OpenFlexure prototype, Maus C, can also be found.

The probe substage allows a hypodermic needle to be used as a probe tip, and fixes to the multipath lighting platform on a reinforced indirect lighting multipath microscope stage which can be found at https://www.printables.com/model/797699 together with adaptors allowing standard NEMA17 steppers to attach to the stage.

Assembly

The probe arm takes a standard hypodermic needle socket - I bend about 4mm of the tip down at a 75 degree angle to make the probe. The arm part of the probe is attached to the probe base with 2 sliding sets of 10mm M3 screws and nuts. The probe body fixes to the lighting stage using 2 x M3 nuts in the stage cavity into which 2x M3 50mm screws are driven. M3 wing nuts and washers apply pressure to the top of the probe base, and two 5mm x 13mm light springs allow compression and movement to be controlled.

Microswitches

The microswitches are 12.8 x 6.2 x 5.8 mm lever switches. I've had a couple of different lever sizes come with them, and if the lever extends past the switch casing I have cut the end off.