A Prunt 3D printer control board is shown mounted in a 3D printer, just behind a power supply, in the center of the image.

Keeping Snap And Crackle Under Control With Prunt Printer Firmware

June 18, 2025 by Aaron Beckendorf 27 Comments

For quite some time now, Marlin has been the firmware of choice for any kind of custom 3D printer, with only Klipper offering some serious competition in the open-source world. [Liam Powell] aims to introduce some more variety with the development of Prunt, a 3D printer control board and firmware stack.

Smooth motion control is Prunt’s biggest advantage: Klipper and Marlin use trapezoidal (three-phase) motion profiles, which aim for acceleration changes with physically impossible rapidity, leading to vibrations and ringing on prints. By contrast, Prunt uses a more physically realistic 31-phase motion profile. This lets the user independently adjust velocity, acceleration, jerk, snap, and crackle (the increasingly higher-order derivatives of position with respect to time) to reduce vibration and create smoother prints. To avoid sharp accelerations, Prunt can also turn corners into 15-degree Bézier curves.

The focus on smooth motion isn’t just a software feature; the Prunt control board uses hardware timers to control step generation, rather than the CPU. This avoids the timing issues which Klipper sometimes faces, and avoids slowing other parts of the program down. The board also seems to have a particular focus on avoiding electrical damage. It can detect short circuits in the heaters, thermistors, fans, and endstops, and can cut power and give the user a warning when one occurs. If the board somehow experiences a serious electrical fault, the USB port is isolated to prevent damage to the host computer. The firmware’s source is available on GitHub.

If you’re more interested in well-established programs, we’ve given a quick introduction to Klipper in the past. We’ve also seen people develop their own firmware for the Bambu Lab X1.

Recore Hacks The Hidden Microcontroller For 3D Printing

June 14, 2021 by Chris Lott 24 Comments

No stranger to the world of 3D printers, [Elias Bakken] from the [Intelligent Agent] workshop has released a new controller board called Recore. The typical 3D printer has a dedicated controller which handles the real-time aspects of driving stepper motors. Many setups also have a second computer, often Linux-based, which is dedicated to supporting tasks like running an Octoprint server and interfacing to a digital camera to monitor print progress remotely. [Elias]’s design merges these together into one compact 12 x 12 x 4 cm package.

The Recore board is powered by an AllWinner A64 system on chip (SoC) which packs four ARM Cortex-A53 AArch64 cores running Debian Linux. The applications include Klipper, a project we wrote about when it was first introduced, and the OctoPrint print server. “But Linux is not a real-time operating system”, we hear you cry, “and controlling stepper motor drivers from an A64 SoC is just asking for trouble”. [Elias] could have addressed this problem by putting a secondary microcontroller on the board, but he found an even more elegant solution instead.

It turns out that there is already a secondary microcontroller hidden in plain sight, integrated into the A64 itself. See that small box labeled AR100 at the top of the block diagram? Meet the AR100, a controller originally intended to manage low-power operations of the A64. It is an OpenRISC 32-bit OR1k processor. But the AR100 is extremely underutilized, and [Elias] takes good advantage of this by repurposing it to those real-time tasks associated with a 3D printer controller. Watch the short video down below to learn how he solves a few of the nitty-gritty implementation details such as timers and communicating with the Linux processors. You might learn some tips from the other short videos in the series featuring some interesting debugging and problem solving sessions. There is a project GitHub repository and a Wiki full of good information and testing results.

[Elias] has a long history of building printer controllers. While his last one had to be abandoned because of manufacturing issues, he learned from that experience. Manufacturability was a top priority in the design of the Recore. We’re jealous of the well-appointed [Intelligent Agent] facility in Norway, but even more so of the nomadic lifestyle that [Elias] appears to enjoy — in his videos, he can be seen working from far-flung locales such as a tropical island resort and a laboratory floating in high Earth orbit. We’ve featured [Elias]’s projects in the past, including the Replicate 3D printer controller, a semi-automatic liquor cabinet, and the dog-operated treat dispenser.

Continue reading “Recore Hacks The Hidden Microcontroller For 3D Printing” →

3D Printer Control Board Packs A Raspberry Pi Compute Module 4

May 1, 2021 by Tom Nardi 51 Comments

Traditionally, 3D printer control boards have used simplistic 8-bit microcontrollers to command the stepper drivers and ultimately move the machine where it needs to go. Newer boards have switched over to 32-bit microcontrollers, but they’re still relatively limited computationally. Because of this, a Raspberry Pi running OctoPrint is usually used to provide more complex features such as remote management and live video.

Looking to combine these different devices into a single all-in-one board, [pkElectronics] developed the Sigmoid S7P. With an STM32 microcontroller, TMC2209 stepper drivers, a Raspberry Pi Compute Module 4, and plenty of room for expansion, it promises to be a drop-in upgrade for essentially any 3D printer running on an open source firmware that could be ported over.

According to [pkElectronics], the idea for the Sigmoid had been floating around for several years, but never got off the ground due to the difficulties in dealing with the SO-DIMM interface used by previous iterations of the Compute Module. But with the switch to smaller and denser connector for the CM4, the board finally started to take shape.

Whether you just used it as a convenient way to integrate OctoPrint into your printer, or want to get into something more advanced like Klipper, the Sigmoid S7P looks like a very exciting project. [pkElectronics] says they are considering producing the board commercially if there’s interest, so if you want one of these for your own custom 3D printer build, let them know.

Tiny Smoothies At Maker Faire

October 5, 2016 by Brian Benchoff 43 Comments

For almost the last decade, desktop 3D printing has, at its heart, been centered around 8-bit microcontrollers. The ATmegas and other Atmel chips are good enough to move a few steppers and squirt some plastic. With faster processors, you get smoother acceleration, leading to better prints. Modern ARM devices have a lot of peripherals, allowing for onboard WiFi and Ethernet connectivity. The future is 32-bit print controllers.

Right now there are a few 32-bit controllers, from the very weird, out-of-nowhere controller for the Monoprice Mini 3D printer to the more traditional SmoothieBoard. Only one of these boards has the open hardware cred for a proper 3D printer controller, and a this year’s Maker Faire, Cohesion3D introduced a few machine control boards built on top of Smoothie that add a few interesting features and techniques.

Continue reading “Tiny Smoothies At Maker Faire” →