Part: Controllers
Designer: Timothy Schmidt
Date: 2013
Tools: 3D printers


Industrial control system (ICS) is a general term that encompasses several types of control systems and associated instrumentation used for industrial process control.

Such systems can range in size from a few modular panel-mounted controllers to large interconnected and interactive distributed control systems with many thousands of field connections. Systems receive data from remote sensors measuring process variables (PVs), compare the collected data with desired setpoints (SPs), and derive command functions which are used to control a process through the final control elements (FCEs), such as control valves.

Larger systems are usually implemented by supervisory control and data acquisition (SCADA) systems, or distributed control systems (DCS), and programmable logic controllers (PLCs), though SCADA and PLC systems are scalable down to small systems with few control loops. Such systems are extensively used in industries such as chemical processing, pulp and paper manufacture, power generation, oil and gas processing, and telecommunications.


Most devices require some internal logic or digital control. Most devices go about that in entirely incompatible ways. Can a single open inexpensive multipurpose controller replace most single-purpose machine control electronics?


Laser additions to open source Marlin 3D printer firmware for, OpenSLS, and mUVe3D demonstrate adaptability of existing ultra-low-cost 3D printing control solutions to a wider range of problems.

A collection of power, control, cooling, and container components are suggested, which connect the elements common to a variety of machine control problems, as well as additions to increase the range of acceptable input and output voltages. This allows the controller to consume power from a variety of solar panel and battery configurations, and to control peripherals originally designed for other applications (i.e. found, salvaged, or otherwise repurposed equipment).



Development targets:

Soldering iron attachment Share inductors across HV, buck-boost, etc. Printed power connector (PETG printed sprung m3 bolt (printed-in-place spring mechanism) and buna-n or ninjaflex O ring panel mount waterproof connector, crimp-on terminal connector for m3 bolt)

Battery charger


  • Hardening - IRFP260N mosfets - 50A 200V mosfets, Higher wattage supplies, smaller board, silicone potted


The replimat controller provides digital electronic control for all replimat projects. The controller works in conjunction with software and builds upon 3D printing and desktop fabrication to provide a generalized solution for machine control problems. The controller bolts to any Replimat frame and provides defacto standard connections for motors, switches and sensors, pumps, lights, and other equipment.

Replimat is intended to work with as wide a variety of hardware as possible. The Replimat software assumes the presence of a microcontroller and an application processor capable of running Linux or another full OS. Hardware documented here is chosen for Freedom as well as cost, availability, and ease of project development. Documentation for other hardware is welcome!



This use of the controller includes 3D printing, plasma, waterjet, and laser cutting, milling and lathing as well as many other tasks automated with machine tools.

  • Firmware support for Emco CNC lathe w/ 6 axis tool changer and spindle speed control
  • Firmware support for Emco F1 CNC mill with quick-change tool post and 90 degree tiltable spindle for side-milling.
  • Firmware support for frame auto-drilling machine

Battery management

Current and voltage sense circuits, voltage and current control, as well as a calibrated load enable the controller to manage a wide variety of battery chemistries.

Home automation

ESP8266 integration allows for interaction with IoT devices.




Part Quantity Link
LCD 1 Amazon
2 wire extension cable 4 ebay
3 wire extention cable 6 ebay
4 wire extension cable 5 ebay
2 wire bare extension 2 Amazon
3 wire bare extension 2 Amazon
4 wire bare extension 2 Amazon
Pre-terminated cables w/ JST-XH lugs 1 Amazon
Controller case 1 CAD
LCD case 1 CAD


Summon FPGA tools
RepRapFirmware Wiki page
RepRapFirmware online configuration tool
LPC1768 port
building on Debian



Part Quantity Link
MKS Base 1 Amazon
LCD 1 Amazon
2 wire extension cable 4 ebay
3 wire extention cable 6 ebay
4 wire extension cable 5 ebay
2 wire bare extension 2 ebay
3 wire bare extension 2 ebay
4 wire bare extension 2 Amazon
Controller case 1 CAD
LCD case 1 CAD



Full installation instructions here.

  1. Download Octoprint from here
  2. Extract .img file
  3. Transfer .img file to SD card using etcher or "dd if=/path/to/file.img of=/path/to/sdcard/device bs=1M"
  4. edit wpa_supplicant.txt on SD card boot partition
  5. insert card into Raspberry Pi
  6. connect power source
  7. open web browser and connect to octopi.lan




Part Quantity Link
MKS Base 1 Amazon
LCD 1 Amazon
Controller plate 1 CAD
Extension cables 2


Laser Marlin

Hardware Comparison

Application Processor (full OS)

SBC Hardware
Raspberry Pi 4 Super inexpensive, ubiquitous, widely supported.
Turtle board Fully open j-core SH2 compatible SoC in Raspberry Pi compatible form factor.
SaxonSoC Fully open RISC-V compatible SoC in microcontroller or application processor configurations
A Trustworthy, Free (Libre), Linux Capable, Self-Hosting 64bit RISC-V Computer ECP5 FPGA based FOSS computer FPGA toolchain

Microcontroller (realtime)

rtos microcontroller board cost
Tock OS SAM4 series DuetWifi+ and clones $80 - $200
Zinc embedded OS, RepRap Firmware STM32F407, LPC1768 Smoothieboard, SKR 1.3, 1.4 SKR Pro
LPC1758FBD80 R2C2
RepRap Firmware SAM3 Duet
Marlin, Laser Marlin Atmega 2560 Rambo, MKS Base
Parallax Propeller
Marlin 2.0 ESP32 R2


Semiconductor Fabrication