I wanted klipper on my MK3S+, but couldn't find any LCD configurations that replicated the default interface closely enough. So I made my own :D.

The following instructions were 80% written by AI. Hopefully it makes sense. This repo is based on charminULTRA/Klipper-Input-Shaping-MK3S-Upgrade and Mithrandil/klipper-config-prusa-mk2s.

I am assuming you have some experience with klipper, mainsail, and ssh.

All changes were made by AI. (So there are likely nonsense comments in the cfg files. I looked over comments in printer.cfg though, so those ones should make sense.)

Warning: I increased machine limits and driver current. Use with caution.

There are still some bugs and visual glitches, but nothing too serious.

Prusa MK3S+ Klipper Config

A complete Klipper configuration for the Original Prusa i3 MK3S+ focused on performance while aiming to replicate the familiar stock Prusa interface.

Features

• Nearly-replicated standard MK3S LCD interface + enhancements
• Increased MK3S machine limits (more dangerous :D)
• Live Z-offset adjustment with automatic persistence without SAVE_CONFIG
• Exclude-object LCD support
• USB Gcode support with automatic disk mounting and file sorting
• Automatically restart Klipper when MCU reconnects (no need to press "Firmware Restart" when MCU boots after Klipper)

Installation

1. Install Klipper + Moonraker + Mainsail/Fluidd on your host

Follow the official Klipper install guide for your host (e.g. Raspberry Pi, or a client install that runs Klipper but flash via USB). That guide covers obtaining an OS image (MainsailOS) or installing via KIAUH, building and flashing the micro-controller to the Einsy Rambo board, and setting the [mcu] serial path. Don't repeat those steps here.

2. Clone this repository

cd ~
git clone https://github.com/<your-username>/PrusaMK3SKlipperConfig

3. Copy the config files (and the lcdconfig folder) to ~/printer_data/config/

4. Copy klipper_modules/mk3s_menu_extras.py to ~/klipper/klippy/extras/

Through ssh, open the file for editing with:

sudo nano ~/klipper/klippy/extras/mk3s_menu_extras.py

Paste the contents of klipper_modules/mk3s_menu_extras.py from this repo, then save.

5. Tune YOUR printer

The config is tuned for my printer. You may want to recalibrate:

• Extruder rotation distance
• PID values (extruder + bed)
• Pressure advance
• Input shaper
• Skew correction

Klipper MCU Auto-Restart Setup

1. Find the printer USB path

Find the path:

ls /dev/serial/by-id/

Copy the printer's device name. The full path will look similar to:

/dev/serial/by-id/usb-Prusa_Research__prusa3d.com__Original_Prusa_i3_MK3_CZPX4222X004XK90480-if00

2. Install jq

sudo apt update
sudo apt install -y jq

3. Create the watcher script

sudo nano /usr/local/bin/klipper-mcu-watch.sh

Paste:

#!/bin/bash

DEVICE="/dev/serial/by-id/usb-Prusa_Research__prusa3d.com__Original_Prusa_i3_MK3_CZPX4222X004XK90480-if00"

while true; do
    if [ -e "$DEVICE" ]; then
        STATE=$(curl -s http://127.0.0.1:7125/server/info | jq -r '.result.klippy_state')
        CONNECTED=$(curl -s http://127.0.0.1:7125/server/info | jq -r '.result.klippy_connected')

        if [ "$CONNECTED" != "true" ] || [ "$STATE" != "ready" ]; then
            sleep 10

            STATE=$(curl -s http://127.0.0.1:7125/server/info | jq -r '.result.klippy_state')
            CONNECTED=$(curl -s http://127.0.0.1:7125/server/info | jq -r '.result.klippy_connected')

            if [ "$CONNECTED" != "true" ] || [ "$STATE" != "ready" ]; then
                systemctl restart klipper
                sleep 60
            fi
        fi
    fi

    sleep 5
done

Replace the DEVICE= path with the path from Step 1.

Save.

5. Make the script executable

sudo chmod +x /usr/local/bin/klipper-mcu-watch.sh

6. Create the systemd service

sudo nano /etc/systemd/system/klipper-mcu-watch.service

Paste:

[Unit]
Description=Klipper MCU Connection Watcher
After=network.target moonraker.service klipper.service

[Service]
Type=simple
ExecStart=/usr/local/bin/klipper-mcu-watch.sh
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target

Save with Ctrl+O, Enter, then Ctrl+X.

7. Enable and start it

sudo systemctl daemon-reload
sudo systemctl enable --now klipper-mcu-watch.service

8. Check status

systemctl status klipper-mcu-watch.service

It should show:

Active: active (running)

---

Automatically Mount USB Drives Inside the Prusa G-Code Directory

This setup automatically mounts USB storage devices as folders directly inside:

/home/pi/printer_data/gcodes/

For example, a USB drive with UUID A644-39EC will appear as:

/home/pi/printer_data/gcodes/A644-39EC/

The resulting directory might look like:

gcodes/
├── BENCHY.GCODE
├── TEST.GCODE
└── A644-39EC/
    ├── FROM_USB.GCODE
    └── MODEL.GCODE

Existing files in gcodes remain visible. The USB is mounted only on its own UUID directory.

When the USB is removed, its UUID directory is removed automatically.

1. Create the mount helper

Create:

sudo nano /usr/local/sbin/usb-mount.sh

Paste:

#!/bin/bash
set -euo pipefail

ACTION="${1:-}"
KERNEL="${2:-}"

if [ -z "$ACTION" ] || [ -z "$KERNEL" ]; then
    echo "Usage: usb-mount.sh mount|unmount sda1" >&2
    exit 2
fi

DEV="/dev/$KERNEL"
STATE_DIR="/run/usb-mount"
BASE_DIR="/home/pi/printer_data/gcodes"

mkdir -p "$STATE_DIR" "$BASE_DIR"

get_mountpoint() {
    local uuid label name

    uuid="$(blkid -o value -s UUID "$DEV" 2>/dev/null || true)"
    label="$(blkid -o value -s LABEL "$DEV" 2>/dev/null || true)"

    if [ -n "$uuid" ]; then
        name="$uuid"
    elif [ -n "$label" ]; then
        name="$label"
    else
        name="$KERNEL"
    fi

    name="$(printf '%s' "$name" | tr -cd 'A-Za-z0-9._-')"

    printf '%s/%s\n' "$BASE_DIR" "$name"
}

case "$ACTION" in
    mount)
        FSTYPE="$(blkid -o value -s TYPE "$DEV" 2>/dev/null || true)"

        if [ -z "$FSTYPE" ]; then
            echo "No filesystem detected on $DEV" >&2
            exit 1
        fi

        MNT="$(get_mountpoint)"

        mkdir -p "$MNT"
        echo "$MNT" > "$STATE_DIR/$KERNEL"

        case "$FSTYPE" in
            vfat|exfat|ntfs|ntfs3)
                UID_PI="$(id -u pi 2>/dev/null || echo 1000)"
                GID_PI="$(id -g pi 2>/dev/null || echo 1000)"

                mount \
                    -t "$FSTYPE" \
                    -o "rw,nosuid,nodev,noatime,uid=$UID_PI,gid=$GID_PI,umask=022" \
                    "$DEV" "$MNT"
                ;;
            *)
                mount \
                    -t "$FSTYPE" \
                    -o rw,nosuid,nodev,noatime \
                    "$DEV" "$MNT"
                ;;
        esac
        ;;

    unmount)
        if [ -f "$STATE_DIR/$KERNEL" ]; then
            MNT="$(cat "$STATE_DIR/$KERNEL")"

            umount "$MNT" 2>/dev/null ||
                umount -l "$MNT" 2>/dev/null ||
                true

            rmdir "$MNT" 2>/dev/null || true
            rm -f "$STATE_DIR/$KERNEL"
        fi
        ;;

    *)
        echo "Usage: usb-mount.sh mount|unmount sda1" >&2
        exit 2
        ;;
esac

Save and make it executable:

sudo chmod +x /usr/local/sbin/usb-mount.sh

2. Create the systemd service

Create:

sudo nano /etc/systemd/system/usb-mount@.service

Paste:

[Unit]
Description=Auto-mount USB storage %I
BindsTo=dev-%i.device
After=dev-%i.device

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/local/sbin/usb-mount.sh mount %I
ExecStop=/usr/local/sbin/usb-mount.sh unmount %I

Reload systemd:

sudo systemctl daemon-reload

3. Create the udev rule

Create:

sudo nano /etc/udev/rules.d/99-usb-mount.rules

Paste:

ACTION=="add", SUBSYSTEM=="block", ENV{ID_BUS}=="usb", ENV{ID_FS_USAGE}=="filesystem", TAG+="systemd", ENV{SYSTEMD_WANTS}+="usb-mount@%k.service"

Reload:

sudo udevadm control --reload-rules

4. Test it

Unplug the USB drive, wait a few seconds, and plug it back in. The drive should be mounted in the gcode folder.

---

PrusaSlicer Setup

There's a tuned PrusaSlicer configuration in the slicer/ folder: slicer/MK3S_Klipper_Config.ini.

Import it in PrusaSlicer:

1. Open PrusaSlicer.
2. Import config (File > Import > Import Config).
3. Select slicer/MK3S_Klipper_Config.ini.