Prunt Board 3 is a 3D printer control board for enthusiasts who want to achieve levels of performance from their printer that are not attainable with existing motion controllers. Our completely new motion control system (named Prunt) outputs motion commands that are smoother than even s-curve motion controllers and uses hardware acceleration to execute motion plans precisely, achieving a large reduction in ringing artefacts in prints and reduced component wear compared to other systems. Additionally our hardware is significantly more robust than any other hardware on the market that we are aware of with protection against electrical shorts between most pins and protection against large ESD events from wires rubbing together that can easily cause damage to stepper drivers on other boards. On top of these core features that are not available elsewhere we have also implemented various smaller features to make using our system a more pleasant experience, such as completely automated firmware updates and the replacement of cumbersome configuration files with a simple GUI. Finally if you find that our software does not fit your usecase then our hardware is capable of running Klipper without having to reflash the firmware and with some additional safety features that prevent an erroneous configuration from damaging the board.

This will soon be available for purchase from CrowdSupply: https://www.crowdsupply.com/prunt-3d/prunt-board-3

The complete source code for the motion control system is available on GitHub: https://github.com/orgs/Prunt3D/repositories

Feature Overview

Hardware

• 6× TMC2240 stepper drivers, all capable of running at 3A with minimal airflow.
• 2× 15A heater outputs with short circuit protection. This is true short circuit protection that will prevent any damage to the board, as opposed to fuses on other boards that will stop a fire but will leave the board damaged.
• 4× fan outputs, supporting 2, 3, and 4 pin fans, all up to 2A with short circuit protection.
• 4× thermistor inputs supporting PT1000 and most common NTC thermistors with protection against shorts to other wires, including heaters.
• 4× endstop inputs with protection against shorts to other wires.
• Fully isolated USB to protect upstream devices.
• Hardware powered step generation for precise timings and step rates that are only limited by the TMC2240 inputs.
• Hardware counters for high-speed fan tachometers.
• Robust ESD protection, this is especially useful in a 3D printer where wires rubbing together can easily generate an ESD event that destroys a stepper driver.
• Buffered thermistor inputs to reduce noise and increase maximum ADC sample rate.

Software

• Fail-safe firmware updates, eliminating the need to ever install a jumper.
• Corner blending with user defined deviation with a higher order of continuity than arcs produced by slicers.
• Constrained and independently adjustable velocity, acceleration, jerk, snap, and crackle for smoother printing.
• Pinout data provided by the board to eliminate the need to edit pin mappings in a configuration file.
• Built-in GUI for configuration editing without the need to ever edit configuration files directly.
• Safer and faster homing by defining maximum overshoot distance instead of speed.

Smooth Motion Planning

G⁴ Motion Profiles

Most popular 3D printer motion controllers (Klipper, Marlin, and RepRapFirmware) only support up to 3-phase G¹ tangential motion profiles, meaning a trapezoidal velocity curve where acceleration is always either zero or the maximum allowed acceleration. This is a problem because an object in the real world simply can not instantly change its acceleration and trying to do make the motors in a 3D printer do so results in vibrations which introduce ringing artifacts in to prints and cause additional wear on components. Some commercial or more obscure open-source motion controllers address this by making the acceleration trapezoidal rather than rectangular, resulting in a 7-phase...