LED print bed levelling indicator

thingiverse

I have been using, from time to time, the trusted paper feeler method to manually tram the Ender 3V2 printer bed and also create a bed levelling mesh. The manual tramming method depends on a good and consistent sense of touch, a suitable piece of feeler (paper or metal) and fumbling with both hands. I believe that there must be an easier way of doing this. At first I used a dial indicator with a mount attached to the X-axis carriage (thing:5346325). This works well except that the instrument, small as it may be, is cumbersome to attach and manipulate. Moreover, the test point is offset from the tip of the nozzle by quite a few centimeters in both the x and y directions, skewing the test points towards the front and right sides of the hotbed. I eventually made this mechanical probe with an led indicator. This probe is equipped with a cantilevered rod with its tip positioned directly below the nozzle. The rod activates a miniature microswitch to light up a small led connected via a 300Ω resister to two small hearing-aid battery cells (AG-7 or similar, not critical). This probe conists of three printed parts: the probe housing, the switch lever and a battery holder cover. The switch lever is hinged onto the housing with a 22mm M3 screw. The assembled device is installed by sliding onto two M6 brass standoffs screwed into the pre-tapped X-axis hotend mounting plate holes. It can be easily removed just by sliding it off. Use is easy and simple. Move the hotend over the desired position with the probe rasied a few millimetres above the bed. The probe is then lowered manually or using the Z-axis control. As soon as the probe makes contact with the bed, the led lights up. I then back up until it turns off again. This method only needs the hotbed to be heated. Because this is an aid and not a mounted accessory, it is not designed to make contact with the axis microswitch stops. Therefore DO NOT home the machine when the probe is in use, otherwise you risk crashing and breaking the probe and potentially (though unlikely) damaging the printer. Material PLA (or PETG with suitable settings) Temperature 195/60° Nozzle 0.2mm Layer height 0.12mm (super quality) Infill 20% cubic Support yes Adhesion brim 8mm Electronic parts used: Mini microswitch (from old mouse) 3mm red led 2 20mm x 6mm brass standoff rods (from old gadget) 1 40mm x 1mm steel rod (from old disk drive) 2 AG7 1.5v silver batteries (or similar) Some AWG30 connecting wires 1 22mm x 3mm Allen screw