Why I made this?

Because I has a Z-offset floating problem caused poorly made original mechanical endstop. At X and Y-axis this small imperfections on measurement are not crucial, but on Z-axis depends to first layer adhesion.

How I designed this?

I want to stay with tffmh's "z braces", which I had mounted on my printer. And this was good starting point to build bracket for optical endstop.

Base for mounting an "optical flag" is "stolen" straight from oldcyclist's project.

I need to cut X-Axis gantry cover for 3mm from bottom, to align original x-axis endstop in factory posiotion.

I designed new interrupt plate which fits on oldcyclist's base and my location of sensor. I make 5mm slot for additional z-offset regulation. It will be crucial in case of swapping different build plates.

What is needed to make this mod?

Parts:

• Optical endstop - I think every cheap optical enstop for 3D printers are all the same
• 3 x M3 screw - If this isn't your first printer mod or you build some PC's you probably have some in spares
• 1 x M3 nut - See up
• 6 x M4x10 screw
• 6 x M4 (v-slot, hammer?) nut
• Some filament - I print this with PETG because I will place my Ender in enclosure. PLA may deform at about 50°C.

Tools:

• Set of Allen keys
• Soldering iron and all electrical isolation stuff

How it works?

Everything goes well and all parts fits perfect in places. Now I may once set bed level and z-offset and don't touch this. Once set, my first layers are very consistent. Now I use this for 3 years, and I don't check my bed level or z-offset even when I remove glass for cleaning. It really solve the problem.

How to mount this?

Hmmm xD Because in this project I use tffmh's "z braces" it's not easiest mod to install. To mount sensor bracket you need to disassembly whole gantry to pieces. Just Ender things.

To wire new sensor you need to find 5V source on yours board. On my Creality V4.2.2 board I simply connect VCC input from sensor to VCC UART output near to display connector (See wiring diagram) I think you may connect this to 5V output for BLTouch, but in this socket pins are shorter and connecor won't stay at place. I know that not every Creality board have soldered pins for UART, then you also may solder this pins, or use buck converter to down voltage from 24V output for hotend fan. Your choice.

Links to desings which I modify:

• Z Gantry braces by tffmh - thingiverse.com/thing:4405701
• Ender 3 opto endstop by oldcyclist- thingiverse.com/thing:3131499
• X Gantry Cover by PJ_Dutchie - thingiverse.com/thing:4641568

If you don't know what you doing - Don't do it! Messing with electricity may cause damage to your printer or fire which may burn your house.