The RPI CNC Board combines a real-time CNC controller (Micro-controller running GRBL) with a powerful credit card size computer (Raspberry Pi).
For the uninitiated, a CNC milling machine is basically the opposite of a 3D printer. With a 3D printer, you’re adding medium from a nozzle to a blank space to create an object. A CNC milling machine starts with a chunk of medium and removes parts of it to create an object, drilling out parts of the medium with great precision while moving its spindle on more than one axis.
CNC milling machines (the CNC means Computer Numeric Control) are really expensive.
So Colin May did what any thinking engineer would do to bring the price down. He built his own, using a Raspberry Pi for its brains.
Colin says:
My friend and I thought about building a CNC Machine for a while. But we didn’t want it to be just an ordinary CNC Machine. We wanted to make a very unique machine that could have very unique attributes. We set out to make a CNC Machine that could do different types of Machining. For example, routing, laser engraving, 3D printing, drag knife, etc. We took about a few months to design the basics of the machine. For example, what kind of linear motion we would have for each axis, what kind of material we would use for it, what kind of style to make it, etc. We chose our build area to be 24″ X 24″ X 7″. After those few months of finalizing everything, we took our first step into physically making the machine. Note: This is made for the average consumer, for home use, and for someone who doesn’t have the money to invest in a $1000 CNC router or 3D printer.
Colin’s machine is still a work in progress, but it’s showing great promise, and we’re very interested to see where he takes it next. Here’s some prototype output:
First test of the machine
And here’s some video. (Turn the sound down if you’ve got a dentist phobia.)
Raspberry Pi CNC Machine Test Pt: 2
Uploaded by Colin may on 2016-04-24.
Colin is intending to add extra functionality: 3D print capability, and some other machine tools – to the setup. You can follow his build and replicate it over at Instructables. Thanks Colin – we’re looking forward to seeing more!
Overview
The RPI CNC Board combines a real-time CNC controller(Micro-controller running GRBL) with a powerful credit card size computer(Raspberry Pi).
By combining the two systems we have created an eco-system where the Raspberry Pi provides benefits like: Processing power, connectivity(IOT) and a well supported community.
The board plugs directly into the Raspberry Pi General Purpose Input/Output pins, with the micro-controller and Raspberry Pi communicating via serial. (/dev/ttyAMA0)
Availability, Update Notifications and Forums
Available online:
Protoneer Shop Zyltech - North American distributor www.BuyaPi.ca - Canadian Distributorwww.piShop.us - USA Distributor MyBotShop.de - Germany - [email protected] Newsletter and Forum
Disclaimer
This products main objective is to provide an affordable Do-it-yourself CNC solution to hobbyists. We can't guarantee that this product will function as intended in industrial environments. We don't take responsibility of damages,injuries or deaths caused directly or indirectly by this product. CNC products are inherently dangerous and we urge user to take care and mind your health and safety first.
Installation and configuration
IMPORTANT: None of the components should be powered while installing or configuring.
Quick Start Guide
WARNING: Do not power up the board with stepper drivers installed if they are not connected to stepper motors. The stepper drivers are current limiting and will overheat if they are not connected.
WARNING: Make sure to plug in the Stepper driver in the right way round. EN of each axis should align with the 'Enable' pin of the stepper driver. (Some Chinese stepper drivers have the printed pin names up side down.)
Raspberry Pi CNC - Quick Start Guide Wiring Diagram
Dimensions: PCB is 55x89mm and with green connectors 59x93mm
Click image to enlarge
Click image to enlarge
Powering the Hat
The MCU is powered by the Raspberry Pi and runs at 5V(Level shifters are in place to allow the MCU and Pi to communicate at diverant logic level voltages).
The external power supply connectors power the Pololu compatible stepper drivers. External driver setup's don't need the external power to be hooked up.
Micro Stepping Jumpers
Jumpers number are indicated as follow:
In the tables below High indicates that a Jumper is inserted and Low indicates that no jumper is inserted.
End Stops
End Stops use normally-open push-button type switches. The End-stop socket shares a common ground that connects to each axis end-stop. The pins are pulled high by the micro controller's internal pull-ups and will activate the end-stop when the pin is connected to ground.
GRBL v0.9 setting $21 needs to be set to 1 to activate hard-limits. Setting $22 also activated the Homing functionality.
V2.51 Introduces End-stop and Probe line filters to prevent noise on the lines.
Endstops can also be doubled up in parallel.
Clone Drive (Introduced with V2.51)
The 4th Stepper Driver Socket can be configured to clone any of the other Axes. Configuration is done with the two rows of solder-able jumpers situated under the board.
In the images above the green sections indicates a jumper positions to configure the 4th Stepper Motor Socket.
!!! The A3 / A4 jumpers are for custom software and allows control of Socket 4 with the A3/A4 pins. !!!
External Driver Boards
External driver boards are great for use with larger external driver like Gecko drivers and TB660 drivers.
The external driver board redirect signals through the green screw connectors on the Raspberry Pi CNC hat and makes it super easy to hook up.
Pin-outs below:
Current version and wiring of the External driver...
The above image has been corrected as the pin names was inverted.
Old Raspberry Pi CNC Hats before V2.6 are orientated this way... Button Controls
The buttons : RESET,ABORT,HOLD,RESUME work with normally open buttons and gets activated when grounded. All buttons are pulled high.
Reset restart the board completely. (Hardware reset and homing needed.)
Abort cancels the current movement but keeps the state of the current machine. (Homing not needed, all done via GRBL)
Coolant, Spindle Direction, Spindle Speed
GCode Commands:
Examples:M3 S500 -> Enables spindle in clockwise direction at 50% speed.
Keep in mind that the direction pin does not reset when the M5 command is used.
Coolant
GCode Commands:
Probe
The probe pin and ground can be connected to a Normally-open switch. Software like bCNC has probe functions and can be used with this board.
Connection To Raspberry Pi
Pinout of the Atmel Atmega328 pins connected to the Raspberry Pi.
Grove Connector
This is great for connecting I2C devices directly to the Raspberry Pi. This only works at the Raspberry Pi's 3.3V voltage levels.
Software (Firmware)
In order for the GRBL to communicate with the Raspberry Pi, the hardware serial port on the Raspberry Pi needs to be enabled and working. HobbyTronics has a good tutorial on how to set it up and test it. Raspberry Pi Serial Port setup
Uploading new firmwareVersion 2.58+
As of this version firmware can directly be upload from the Raspberry Pi.
Upload procedure
The Raspberry Pi V4.00 image includes script to update the firmware on the Raspberry Pi CNC HAt.
Upgrade Procedure
Before shipping each board we test the firmware and we use the same script to upload the initial firmware before automated testing starts.
The upload script uses Python GPIO libs and sometimes does not upload the first time while the pins gets configured.(Bootloader timing issue that happens rarely) If so try a second time.
Older version
Firmware gets uploaded from the Nano's usb port.
GRBL Firmware
GRBL is the magic that does the actual control of the CNC machines.
For more details : GRBL
The Raspberry CNC board comes pre-loaded with GRBL but can be updated as follows : Flashing Grbl to an Arduino
Firmata
Will be added soon.
TroubleshootingHardwareVersion 2.60
Version 2.58
Version 2.51
Version 2.11
Retrieved from 'http://wiki.protoneer.co.nz/index.php?title=Raspberry_Pi_CNC&oldid=29557'
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