MRRF: ARM-Based CNC Controllers


8-bit microcontrollers are the standard for RepRap electronics, but eventually something better must come along. There has been a great deal of progress with ARM-based solutions, and of course a few of these made a showing at the Midwest RepRap Festival.

First up is [Mark Cooper], creator of Smoothieboard, the ultimate RepRap and CNC controller. It’s an ARM Cortex-M3 microcontroller with Ethernet, SD card, and up to five stepper drivers. It had a Kickstarter late last year and has just finished shipping all the rewards to the backers. In our video interview, [Mark] goes over the functions of Smoothieboard and tells us about some upcoming projects: the upcoming Smoothiepanel will feature a graphic LCD, SD card, rotary encoder and buttons, all controlled over USB by the Smoothieboard.

Next up is [Charles] with a whole bunch of CNC capes for the Beaglebone. By far the most impressive board was a huge I/O expander, motor driver, and everything controller for a Beaglebone featuring – get this – three parallel port interfaces. This was a one-off board costing thousands of dollars, but [Charles] did show off a few smaller and more practical boards for Beaglebone CNC control. Here’s a link to [Charles]‘ capes.

Videos below.

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Smoothieboard, The Be-all, End-all CNC Controller


A while back we took a look at electronics boards for 3D printers, going over the cost and benefits of the most common electronics boards for printers, laser cutters, and mills. One of the most impressive boards was the Smoothieboard, but finding a supplier back then was a little difficult. Now, the Smoothieboard is up on Kickstarter, giving everyone the opportunity to get their hands on this very cool CNC control board.

While most RepRap and 3D printer controller boards use an ATMega or other 8-bit microcontroller, the Smoothie uses a 32-bit ARM chip in the form of an NXP LPC Cortex-M3 chip. Not only does this allow the Smoothie to do some very cool things with your machine – native arcs and circles, for example, but this better hardware also allows for Ethernet, drag-and-drop firmware, and exposing the USB port as both a serial port or mass storage device.

The Smoothie comes in three flavors, with either 3, 4, or 5 stepper motor drivers. These Allegro A4982 drivers are good enough for any 3D printer, laser cutter, or small mill, but the broken out pins allow for stepper drivers supplying more than 2A of current.

Everything on the Smoothieboard is modular, meaning this board is equally capable of powering a RepRap, mill, laser cutter, or plotter. There’s even a planned control panel called the Smoothiepanel, making this a great choice for your next CNC build.

H-bot style 3D printer moves bed for Z-axis


Check out this 3D printer (translated) which [Arkadiusz Śpiewak] has been working on. When sending in the tip about his project he made the important distinction that it isn’t finished, but he has reached that critical threshold where he has printed items with it.

He decided to go with a design that is sometimes referred to as an H-bot. If you’re completely unfamiliar with it, you may find this H-bot design article helpful. The gist of it is that this technique makes it so that the motors used to move the extruder along the X and Y axes are themselves stationary. One large timing (toothed) belt makes a circuit around the top of this cube in the shape of the letter H. This is a bit easier to see in [Arkadiusz's] rendered image found after the jump along with video of an early print test.

The Z axis uses two motors mounted along the bottom of the cube. These raise and lower the bead, instead of moving the extruder itself. All-in the printer should have a maximum object size of 30x30x30 centimeters. It’s being driven by a Smoothieboard, which was mentioned quite a bit when we were discussing using the RA driver board with a 3D printer.

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