The Pi CNC Controller


Back in the olden days, the latest and greatest CNC machines had minicomputers bolted onto their frames, replete with paper tape readers and seven segment displays. For the home CNC machinist of today, these hulking electronic brains are replaced with something a little more modern – desktop computers with parallel ports. Having a box filled with computers and motor drivers is just too cool though, and this tiny Raspberry Pi CNC controller fits the bill quite nicely.

The controller uses a Raspberry Pi as the brains of the device, but there aren’t too many options out there for stepper motor control in Pi land. There are, however, dozens of CNC shields or the Arduino. The Pi AlaMode board is able to provide voltage level conversion between the CNC shield and the pi, and also has the nice bonus of a battery-backed real time clock.

With some proper connectors, lighted buttons, and a beautiful cable sleeving job, this Pi CNC controller would be well suited for any of the desktop CNC  or engraving builds we see from time to time.


GRBL compatible Arduino CNC shield


By the time you get to the point in a home CNC build where you’re adding control electronics you may be ready for the simplest means to an end possible. In that case, grab your Arduino and heat up that etching solution to make your own GRBL compatible shield.

This familiar footprint manages to contain everything you need for a three-axis machine. The purple boards slotted into the pairs of SIL headers are Pololu Stepper motor drivers. Going this route makes replacing a burnt out chip as easy as plugging in a new module. The terminal block in the center feeds the higher voltage rail necessary for driving the motors. The DIL header on the right breaks out all of the connections to the limiting switches (two for each axis), spindle and coolant control, as well as three buttons for pause, resume, and abort. There’s even a header for SPI making it easier to add  custom hardware if necessary.

This is a dual-layer board which may not be ideal for your own fabrication process. [Bert Kruger] posted his Gerber files for download if you want to put in a small run with OSH Park or a similar service.


Handwriting suck? Build a machine to do it for you


Children of the information age are doomed to have the worst handwriting just for lack of use if nothing more. But some students at Olin College harnessed technology to find a solution to that problem. Meet Herald, a CNC machine that can produce beautiful calligraphy.

The machine uses a gantry to move the writing tip along the X and Y axes. The flexible-nib calligraphy pen is mounted on a sprocket which rotates the tip onto the writing surface, taking care of the third axis. The rig was beautifully rendered from their CAD drawings, then tweaked to ensure the smoothest motion possible before the quintet of Sophomores began the physical build.

The drive hardware is very simple yet it produces great results. It uses an Arduino along with three stepper motor drivers. There are also limiting switches to protect the hardware from runaway code. The software interface designed by the team lets the user cut and paste their text, and select a font, font size, alignment, etc. It then converts the text to G-code and pushes it to the Arduino where the GRBL package takes care of business.

Don’t miss the device in action, writing out a [Langston Hughes] work in the clip after the break.

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CNC hardware: stream g-code to an Arduino

[Reza Naima] has been using an Arduino as the center of his CNC setup for quite some time now. It handles three stepper motors, limiting switches, e-stop, and spindle control. The sketch he’s using allows him to stream g-code to the popular prototyping platform, freeing him from needing a dedicated PC. It’s worked so well that he’s decided to clean up the code and develop a shield to help others get up and running. If you want to see his progress or lend a hand, check out the google group he started for the schematics, code, and forum discussions. There is already a CNC project for Arduino called Grbl but [Reza's] approach uses the Arduino libraries in an effort to make the sketch more customizable for the average user.