Picture of Raspberry Pi Alamode CNC Controller
CNC Diagram.jpg

This is my first attempt at an instructable. I hope it helps someone else.

Switches and Lights and fans, oh my...

Please read through the comments for more details.

I bought a CNC machine some time ago and I was never happy with it. It used a traditional parallel port controller and of course no modern computers have those. So it was always a point of frustration. I used an old Pentium based computer and ran LinuxCNC on it for a while but was still not happy with that. So I started looking for another solution. I decided that I would try to put together an Arduino based controller and try to use USB to communicate with it.

After studying that for a while I came to realize the Arduino was just not going to be able to do all that needed to be done on its own. The Arduino UNO just does not have enough memory or processing capacity to process a design file by itself. So I modified my solution and started working on using a Raspberry Pi as my host computer.

I created a Visio drawing of what I intended to do: It didn't turn out that way and the drawing continued to evolve as I learned more. It kept on changing until I finally got my project completed.

I have now built an Arduino based CNC Controller system that uses a Raspberry Pi as its host computer. The Raspberry Pi processes an "nc" file that contains a design that is described in GCode commands that can be understood by the Arduino. I have used a few tools on my Windows 8.1 Pro laptop to design a few simple things (like tutorials in makercam here: This is a great introduction to designing things for CAD/CAM and it is really easy to use.

After creating a design that I wanted to use I wirelessly connected to the Raspberry Pi using WinSCP to transfer design files to the Raspberry Pi. You can get WinSCP here:,44532390848,winscp20download,e,,c,0,,,&gclid=CJuIkNHds74CFagWMgodpxMAJw. Its great, you can just drag a file from one window to the other to move files between systems. You will have to know the IP address of your Raspberry Pi to connect to it. If you have gone through the initial setup of the Raspberry Pi and setup a network connection you can get the IP address by using the ifconfig command on the Raspberry PI. A really helpful tool for getting your IP address and seeing that your Pi is online is a tool called the Advanced IP Scanner here: Another great tool is Wireshark:

I then used Remote Desktop Connection (Remote Desktop connection is part of Windows and should be on your Windows machine. It can be run by entering mstsc in the Run Open: box) to connect to my Raspberry Pi. Otherwise you could use VNC or TightVNC: TightVNC is what you need to put on your Raspberry Pi to allow you to use Remote Desktop Connection from another machine. I can now run the Grbl Controller on the Raspberry Pi which in turn connects to an Alamode (an Arduino like board that plugs directly into the GPIO connector on the Raspberry Pi and provides automatic voltage level translation. So that the Arduino can communicate with the Raspberry Pi directly. The Alamode also provides Arduino headers to allow for Arduino shields to be plugged directly into it. So I ended up with a stack of three boards that are tightly integrated due to being plugged directly into each other. The Alamode (Arduino) processes the GCode commands from the Raspberry Pi into signals that are sent to the CNC Controller shield to run the stepper motors and passes the various function signals on to the CNC Controller shield too. They can then be accessed from the external world. All is well so far... But now I have to connect these things to the external world.

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Step 1: 100% Grbl Compatible CNC Controller

Picture of 100% Grbl Compatible CNC Controller

First, I purchased the 100% Grbl compatible CNC Controller shield from: I already had an Arduino and intended to use that with the CNC Controller shield and run something on my laptop to control everything. Then I found out that the Arduino would not be able to process an entire design file all by itself. This is due to it not having enough memory to handle more than one GCode command at a time. In fact not all GCode commands are currently completely implemented in the Arduino Grbl software. However, the Arduino does directly interface with the CNC Controller shield and can pass commands to the stepper drivers on the CNC Controller shield without any additional circuitry.

The sets of three yellow jumpers that you see in the pictures set the micro stepping for the stepper motors. The one single yellow jumper selects how the limit switches work. Mine are set up so that when the switch closes a ground is detected (the default). The alternative is to sense a hi when Vcc is selected. That is to say that the limit switch logic can be set to sense a hi or lo, your choice. The two yellow jumpers on the left side of the picture are for selecting which axis the A-axis mirrors (two motors on one axis).

I used polarized headers to connect to the stepper drivers so that I would not be able to plug in my stepper motors backwards - that's pretty important.

The 100% Grbl compatible CNC Controller shield does not actually include any stepper motor drivers. It is only a means of integrating the stepper motor drivers into an Arduino shield conveniently and it works great for that purpose. The CNC Controller shield is designed to use the Pololu type step driver modules like the A4988 stepper motor driver carrier that is shown here:

I purchased some from China that were about $4.00 each and appear to be exactly the same (we shall see when I actually try to use them). They came with some heat sinks too but I decided to use the ones you see (from Adafruit) instead of the ones that were included instead. You actually only need to populate the X, Y and Z stepper driver carriers on the CNC Controller board (because the Grbl software on the Arduino only knows about three axes). Unless you intend to use the A-Axis too (for a second motor on one of the primary axes). The CNC Controller allows you to mirror the control signals from X, Y or Z to the A axis by using jumpers. I am not using the fourth axis. I just included the fourth stepper driver carrier so that I would have a spare in case one of the others stops working. Then again who knows what might be in the future?

Step 2: Raspberry Pi

Picture of Raspberry Pi

It became clear that I needed some way to process a complete design file and break it into individual GCode commands that the Arduino could then pass on to the CNC Controller shield. Many articles are available on the internet about running the Grbl Controller software which provides this specific function on a Raspberry Pi. I had a Raspberry Pi that I had played with a bit, some time ago, but it was an older version. I am sure it would have worked but I decided to get a new one and dedicate the new one to being the host in my new CNC Controller system. For more information about running the Grbl Controller software on a Raspberry Pi look here:

Due to reading a lot of those articles that I mentioned I became concerned that the Raspberry Pi would overheat when inside of an enclosure so I put heat sinks on it. Then I had to trim down the heat sink on the processor as it was too tall.

I also came to realize that the Arduino and the Raspberry Pi are slightly, electrically incompatible. The Arduino operates with 5V logic and the Raspberry Pi operates with 3.3 V logic. So a voltage level translator of some sort is required as an interface between the two environments. I looked around for a solution and found a few. I didn't really like anything that I was finding and it took a while to get to what I wanted but I eventually found the Raspberry Pi Alamode board.

Step 3: Raspberry Pi Alamode

Picture of Raspberry Pi Alamode

The Alamode board plugs directly into the GPIO connector on the Raspberry Pi and provides the level shifting function that is needed for the Arudino to communicate with it. It also provides Arduino compatible headers so that any standard Arduino shield can be plugged into it too. Including the CNC Controller shield. So it now appeared that I could have a stack of three boards that communicate with each other properly and elegantly - with no additional circuitry required.

Some quick features of the Alamode - that I am interested in: The Alamode has a real time clock that is directly available to the Raspberry Pi (with a coin cell battery backup). The Alamode can be powered from the Raspberry Pi or it can be powered directly through its own micro USB connector. There is a tiny jumper that allows you to select how you want to power it. The jumper header fell off of my board (probably my own fault). I looked at it and decided I just didn't need it as I intended on powering it through its own micro USB port anyway. The big deal is that the Alamode includes the signal level shifting that is required for an Arduino to communicate with a Raspberry Pi.

Once the Alamode is connected to the Raspberry PI you can then load the Grbl software onto the Alamode. The Grbl code is loaded into the Alamode with the Arduino IDE. You need to load the Arduino IDE onto the Raspberry Pi to load the Grbl code into the Alamode. The Getting Started instructions at the Alamode site are very good and complete: Refer to the User Guide for instructions on how to set up the real time clock.

Let me just say that it works exactly as they say it does. It is a bit of a task to get everything together to actually use it but once it is set up (mostly on the Raspberry Pi) it works great.

Step 4: Stack 'em Up

Picture of Stack 'em Up

So now I have a stack of three boards. With the Raspberry Pi on the bottom, the Alamode in the middle and the CNC Controller shield on the top. All plugged together. One problem for me was that the Alamode does not provide any mounting holes. It does provide a rubber pad that goes on the top of the RJ-45 Ethernet connector on the Raspberry Pi and is the right height (must be very carefully positioned on the RJ-45 connector) but there is no solid connection point other than the GPIO connector. The CNC Controller shield is like most other Arduino shields and is very well held in place due to the friction of the header extenders that are on the Arduino. My original Raspberry Pi did not have mounting holes in it either. That is part of the reason why I decided to get a new one and use it instead. Later on, I purchased an assortment of nylon standoffs and attached a couple of them to the Raspberry Pi - with a couple of washers to get the height right. Then I very carefully put a drop of super glue on the top of each of the nylon standoffs and put the Alamode onto the Raspberry Pi. I then left it alone for a while. I was later able to take the screws out of the bottom of the Raspberry Pi and take the Alamode off with the standoffs attached to the Alamode - it worked! I also attached a standoff between the Alamode and the CNC Controller shield as there was a hole in a place that made that possible on both boards. So now I have all three boards securely connected together.

Step 5: An Enclosure

Picture of An Enclosure

Early on I decided to use some sort of enclosure to protect my finished project. So I bought one and then came to realize it was not large enough and had to measure everything and buy another one. The one I used is is nice box but turned out to be a challenge anyway. This box is made by Bud and I got through Amazon here: It is a BUD Industries PN-1339-DG High-Impact ABS NEMA 4x Indoor Box, 6-19/64" Length x 6-19/64" Width x 3-17/32" Height, Dark Gray Finish enclosure.

There are some nice brass threaded mounting holes in the corners inside of the box and the box comes with screws to secure the top to the bottom with the brass threaded holes in the outside corners. The box also has a gasket to make it waterproof if you need that. In my case it just makes for a very nicely sealed box.

I came to believe that I needed to have some sort of carrier to mount my "stack" to inside of the box. So I bought a sheet of acetal from Zoro Tools: Acetal is supposed to be somewhat ESD safe but I have not studied that out entirely either. After I got the sheet of acetal I cut a piece that would fit inside of the enclosure with my Dremel tool. It isn't pretty and this is one of the things I plan to replace when I finally get my milling machine working again. I ended up having to cut cutouts on both sides of my initial carrier to provide better access for the wires and cables that connect the "stack" to the external world.

I also felt that it was important to make sure that there is adequate ventilation in the box. So I mounted two 40mm, 12 VDC, exhaust fans on the top and two inlet vents with filters on the bottom.

In the pictures you can see that there are a couple of extra holes in the carrier - Oops.

I made a 1:1 scale drawings of the openings to be put into the box in Visio and then printed those out on my printer. Then I cut out the printed drawings and taped them to the box and used them as templates. It wasn't perfect, of course, but was pretty good. I started each modification to the box by using an Exacto knife to carefully mark through the templates and then used a Sharpie to make sure I got it right. Then I used my Dremel to cut out the various openings in the box. Not too difficult to do but you have to be patient and let the Dremel do the work or you will end up with a lot of melted plastic on your hands and the nib that you are using in the Dremel will try to dig into the material occasionally. My only advice is be patient, take you time, don't press to hard, cut in the right direction and it will all work out acceptably - no one is perfect. The hardest openings to cut were the ones for the switches and the connectors. Each of the connectors and switches have flat spots on opposite sides. All of my switches and connectors are 16mm. The flat spots keep the switches or connectors from turning in the chassis. That is great if you are using chassis punches but I do not know of any of those that are designed to work on plastic. So I had to very carefully cut the holes by hand with my Dremel. I cut them and test fitted each connector one at a time and as soon as I was able to get the switch or connector in the hole I stopped. They are pretty good but a nice CNC machine would have done a better job than I did - maybe next time I will have a working CNC machine and I can try that.

Step 6: The Hard Part

Picture of The Hard Part

So here is the hard part. Most CNC machines (milling machines, laser cutters, engravers, water jets, etc.) use stepper motors to position the axes. The CNC Controller board provides X, Y and Z axes as well as an A-Axis that can be used to supplement one of the other axes if needed with an additional motor or a fourth axis could be implemented (but Grbl only knows about three axes right now). My implementation is only going to use three axes at this time. However, I decided that I needed to bring the A-Axis out because I might someday want to use it. Further, the CNC Controller board provides for the control functions to enable the spindle as well as two other functions. By default they are spindle cooling and spindle direction (alternately these functions can be used to control a laser, a vacuum hold down or a blower / fume extractor and a heating mat for a 3D printer). I did not know what I might want to control later on so I decided to bring those signals out of the box too. I ended up with five connectors on one side of my box that can be used to connect to the machine that I want to control. I have labelled everything and everything is also color coded.

I want to mention that I used expandable sleeving to bundle wires together where ever possible and to reduce the number of unbundled wires in the build. It helps in a lot of ways and protects the wires a bit but most importantly it makes it really clear what each of the bundles is for. It also makes the entire project a lot better looking. Here is one place that you can get expandable sleeving: NTE provides wire and heat shrink tubing assortments that are really useful in building electronics.

NTE / Elenco hookup wire assortment:

Heat shrink tubing assortment:

Other useful things are like these:

Crimping Tool to put pins onto the ends of wires to be plugged into the various places: This is a really nice tool and works better than a lot of other crimpers that are a lot more expensive. Of course, you need to have pins and housings to complete a connection. You can see that I used many pins and housings in building my CNC Controller.

Step 7: The External World

The next thing that had to be done was to connect the inside of the box to the external world. Switches to control the system and plugs to get the signals to the stepper motors and the spindle and finally a connection to a power supply.

The switches are all connected to one header that plugs into the CNC Controller shield and another one that plugs into the power distribution board for the LEDs that are in the switches. So the switches have a connection both below the carrier and above the carrier.

The switches are E-Stop or Arduino Reset (Red), Abort Reset (Yellow), Pause / Feed Hold (Blue) and Cycle Start / Resume (Green). The Reset, Abort and Hold switches are push-push switches. That is they stay pushed in until you push them again. That gives a positive indication of whether or not a button was pushed. The Resume button is a momentary push button and only stays in as long as you hold it in. Each button illuminates so that you can clearly see if it is pushed in or not. As you can see in the pictures I used colored expandable sleeving and shrink tubing of the same color as the button for each function to make it easier for me to keep everything straight.

The connectors on the other side of the box are color coded too. They are X-Axis (Green), Y-Axis (Blue), Z-Axis (Red), A-Axis (Purple) and Spindle (Yellow). These colors match up with the cables on my milling machine. The X, Y and Z axes contain the wires for the stepper motors and for the limit switches. The A-Axis is only stepper motor wires and will not be used on my milling machine. The Spindle connector has the Spindle Enable, Spindle Direction and Cooling Enable wires in it. Again you can see that I tried to use the same color expandable sleeving and heat shrink tubing as much as possible.

I connected the two 12 VDC exhaust fans to a header that eventually connects to the power distribution board.

Finally, I used a PowerWerks PowerPole snap-in chassis mount that provides 5 VDC through a red connector and red cable, 12 VDC through a yellow connector and yellow cable and a ground for each side through black connectors. The chassis mount holds the PowerPole connector housings in place inside of the snap-in chassis mount with a pin and these connectors are very well made. More information about the PowerWerks PowerPole connectors can be found here:

Externally I am using an ATX power supply that has been slightly modified to provide power for my milling machine (it came with my machine). I built a cable with the PowerWerks PowerPole connections on it that match up to my CNC Controller box PowerPole snap-in chassis mount. Later on I added an emergency power off switch to my power supply. You can see the emergency switch here:

Hooking up the switches and the connectors was the most time consuming part of the build.

Step 8: Power Distribution

Picture of Power Distribution

The next issue was how to get power to my "stack". I decided to build a power distribution board. I also had an issue with the switches that I used. As you can see they have LEDs inside of them. The LEDs are completely separate from the switches. On top of that the switches just provide a path to ground for the CNC Controller / Alamode. So, to get the LEDs to light up when the switch is depressed I had to use an inverter (SN7404 Hex Inverter). The LED power function is most of the circuitry on the prototype board. Power is on the edges with 5 VDC on one edge and 12 VDC on the other edge. The four resistors are current limiting resistors to limit the current going through the LEDs. The 12 pin header is where the switches plug into the board. The headers provide power for everything in the box. 5 VDC for the Raspberry Pi and the Alamode. 12 VDC for the fans and the 12 VDC circuitry on the CNC Controller shield and for the 12 VDC path through the relays. The black connector on the prototype board is used to provide the grounds for the signals being controlled by the relay stack. Notice that I tied all of the grounds together on the power distribution board.

I used a temporary breadboard to figure out how to get the LEDs to work the way I wanted them to work. Then I moved the circuit to an Adafruit Perma-Proto Half-sized Breadboard PCB. It went pretty quickly and easily.

There are pull up resistors in the Alamode (Arduino) that pull up the voltage to near Vcc on the Alamode for each of the functions. A function change of state is sensed when the voltage is pulled lo or to ground. The CNC Controller shield provides the function pins and matching ground pins. Shorting the function to ground changes the state of the function and is sensed by the Arduino code. I wired up the switches to do just that. Press the switch and the function is connected to its respective ground pin. However, I also ran a wire from each of the switches to one of the four Inverters that I used (two of the inverters in the HEX Inverter chip are not used). So that when the switch is open a high or Vcc is on the input to the inverter which results in a low is on the output and the LED is off. Pressing the switch puts a low or ground on the input to the inverter and hence the output of the inverter transitions to a hi and the LED turns on.

Step 9: Putting it all together

Picture of Putting it all together

I looked into connecting a video display to the enclosure but did not have enough USB ports. So I bought a 3-port USB hub. It came in a black plastic housing but that was way too big to fit into my box. So I took it out of its housing and then used a zip tie to anchor it to my carrier. Now I have four usable USB ports. One has a wireless network adapter in it. I also used one with a miniature keyboard but I am not using it now as I am using the Remote Desktop Connection instead. I also looked at adding an LCD display to the box but found that I just do not have enough room in the box. Another of the USB ports would have been used to connect a touch screen to the system.

Next I attached the stack to the top side of the carrier and the power distribution board to the bottom side with nylon standoffs.

The last pieces to go onto the carrier were the relays. There are three relays. One for the spindle, One for spindle direction and the last one for spindle cooling. They got put into a stack and mounted on the carrier with nylon standoffs too.

Step 10: Wiring the carrier

Picture of Wiring the carrier

After getting all of the pieces mounted on the carrier they needed to be connected electrically. I built a small wiring harness to connect the relays to the power distribution board and to the CNC Controller board. Each relay connects to its control pin on the CNC Controller board (the white expandable sleeving bundle). Then each relay gets connected to the power distribution board for 12 VDC power. On the other side of the relays I made a couple of cables that provide the ground for the signals being controlled by the relays and a very small cable to connect the relays to the spindle connector. It is sleeved with yellow on this side as it connects directly to the Spindle connector on the side of the box. I used inline connections to allow me to more easily disconnect the cables and get the carrier into and out of the box.

The relays are controlled directly from the Alamode via the CNC Controller shield. Of course, you could use these three relays to control the functions mentioned but they could also be used to control the functions of the print head and heat pad on a 3D printer or a LASER in a laser engraver along with a fume extractor or whatever. I plan on being able to move this control system between all of those environments in the future - unless I decide to dedicate this one and build more of them for my future machines. It would also be really easy to use the 5 VDC relays to switch 12 VDC and then use that to control a solid state relay or whatever is wanted.

I built another small wiring harness to connect 12 VDC from the power distribution board to the CNC Controller shield. This 12 VDC is used to power the stepper motors.

Step 11: Installing the carrier

Picture of Installing the carrier

Now it was time to install the carrier with all of its boards and cables into the enclosure. The hardest part is connecting the power to the power distribution board. First I plugged in the connector to the LEDs that are in the switches. Next comes the fans and finally the power. Everything is color coded because I am notorious for incorrectly connecting things. The cables that are attached to the switches and the connectors have to be gently pushed and pulled to get the carrier in the box but once there is sits comfortably.

Step 12: Connecting to the external world

Picture of Connecting to the external world

After getting the carrier board connected and in place and then screwed down at its corners the remaining steps are to connect the switches to the CNC Controller shield. Followed by connecting the axes cables to the CNC Controller shield. Finally the last connections are the relays and the ground for the spindle connection. It is tight but there is enough room for everything to fit nicely into the box.

Step 13: Testing

After getting everything hooked up I powered up the box and started testing everything. The switches worked and I was able to control the system as I thought it should work.

Next I went to my laptop and used the Remote Desktop Connection to log into my Raspberry Pi.

I had already installed the Arduino IDE on the Raspberry Pi and done a lot to prepare to run the system. It was a learning experience and I did not know what else I might need to do to make everything work. So I got the software working before I ever put anything in the box. The biggest difference between my getting the software working and the current state is that I now have the switches too and can control the system by pressing those buttons and it all works.

I ran the Grbl Control program on my Raspberry Pi and connected to the Grbl program that is running on the Alamode. I opened a file that I had created (a modified coaster tutorial) and ran the program. It ran all the way through and stopped as I expected it to.

I checked to make sure that nothing got hot. Now I have to get out my milling machine and get it back together and try to make something.

Thanks for reading my instructable.

Let me know what might have done differently. Maybe I will make another one.

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JohnM5711 days ago

Thanks for you response. My machine is simiIiar in table design to a plasma, or router CNC except it is being used for pressure testing of foam materials. That's why the Z axis is just a actuator with a load cell. The table moves to a location and then the actuator drops to mutliple depths while the load cell readings are recorded. I was expecting that the drivers and power supply would be outside of your enclosure design and in a separate one. Ultimately, I'm wanting to input the control signal into my set of drivers. It seems like this should work. The signal going to the driver should be the same regardless of the driver correct?

Can you tell me what value your current limiting resistors are and also the model of your fans.

cdtaylor51 (author)  JohnM573 days ago
I believe that you are correct about there driver signals but you need to confirm what your particular drivers are expecting. The current limiting resistors for the leds are about 500 Ohms. Just check out an led resistor calculator on the internet and decide how much current you want to light up the led and the led calculator will give you the value of the resistor to use. I didn't want leds to be very bright and I want them to last a long time so I used the resistors that I used. You might want the leds to be brighter or less bright. I would suggest that you use a breadboard and try some different resistor values and see what you prefer. I hope this helps.

Your input is a great help, Thank you! I have about 1/3 of the compnents in. I didn't realize the CNC shield had to be assembled, but the supplier sent the link to the assembly instructions so I'll be ok. Adafruit was an awesome find! I really like their approach to marketing their products by educating their viewers on their products and applications. Great for novices like myself. Since I started this project i'm fiinding all kinds of educational stuff on youtube, and the raspberry pi site as well!

cdtaylor51 (author)  JohnM572 days ago
No problem. I would like to see a picture of your build when you get it finished.
cdtaylor51 (author)  JohnM573 days ago
The model number of the fans is in the parts list that I posted in response to a previous comment. Nothing special, just 40x40x10 mm 12VDC case fans.

That is an awesome CNC controller and your wiring is perfect! Thanks for the explaination..
How do you find the grbl controller software? have you compared it to something like LInuxCNC or Mach3/4? Also this would work with a larger stepper motor driver for the likes of a Nema23 or 34 right? or is the output voltages not enough to fire the drivers? Thanks!

cdtaylor51 (author)  troy.dawson.779851 month ago
Thanks for the feedback. You can just Google for grbl and then read the Wiki pages for info on grbl. Grbl is available on github. As for larger motors: the grbl controller board is designed to handle 12 to 36 volts (you would want to read their pages too). There are a few different Pololu stepper driver modules that you can use at different voltage and current settings. Of course you would need to modify the wiring and perhaps provide better cooling if you used different power levels than I did. Just changing the power and the driver modules would be pretty easy to do. My build just used 5 volts and 12 volts. To use 36 volts you would have to bring 36 volts in from an external 36 volt power supply to the CNC controller board and you would need to replace the stepper driver modules with appropriate 36 volt modules. I also used 12 volts for my spindle functions. You may have different requirements than I have.

This is really an awesome CNC project. Thank you for sharing all of this hard work. I'm working on a 3 axis gantry style CNC project now and have been thinking about how to use your design. Instead of a spindle on the z axis i'm using a actuator powered with a servo motor (so I'm not needing any relays for spindle speed, direction or coolant since there is no spindle motor), and stepper motors for the xy. A load cell is set on the end of the actuator. I'm looking to use nema 34 steppers with R1025 drivers. I'm still researching the servo for the Z axis since I need more torque for the actuator. Any thoughts or suggestions?

cdtaylor51 (author)  JohnM5712 days ago
Thanks for your interest in my project. There are a lot of things in my project that might be applicable to yours. However it is clear that your project would not fit into a small enclosure like mine did. As for the z-axis, you might be able to use a rotory solenoid actuator to get higher torque. I don't really know what you are doing so I can't really say that would work but it might be worth looking at. Thanks again for your comments and questions.

Sweet Thanks for the reply. I know I would need to use external motor drivers. But I wasnt sure if it works as a relay and therefore could be driven by a lower voltage or if I need to run the actual voltage through the board.

My requirements are to convert a Optimum BF20L Mill which would require Nema34 motor and 2 Nema 23 motors. But the raised voltage may mean I need to use a conventional board as opposed to a GRBL/Arduino setup.

cdtaylor51 (author)  troy.dawson.7798526 days ago
You could certainly try using a CNC controller just like mine if you wanted to. As I mentioned previously you would need to provide the right voltage for your motors but there are driver modules that can handle up to 36 volts and 2.2 amps per coil. You could try that and Grbl if you wanted to. If it's too much then you could do something else and still have this controller as a backup or to test with or to use on another project. Personally I think my CNC controller would work (use the 8825 drivers at the correct voltage for your motors and leave the top off of the box until you understand the thermal issues). Alternatively, you may need functions that are not available in Grbl. So you might want to go with Mach or EMC or LinuxCNC or something else and that would mean that you wkuld not be able to use this controller. By the way, I really like the mill you chose. I would suggest that the first thing you do is install a good Digital ReadOut (DRO) on it. Then learn to use it manually. Then upgrade it to a CNC controlled machine. Make the parts to adapt it yourself. Learn all you can about using the machine first. Then you will understand what happened and why it happened when something goes wrong and you will be able to compensate for that intelligently.
cdtaylor51 (author)  cdtaylor5126 days ago
Check out this site for a great DIY DRO project:

This is an awesome CNC controller - thank you for spending time and effort sharing the results in such great detail.

I too am going to make a similar CNC controller and if possible would like to know a bit more about your S port and the relay(s) you used and how you have them wired in.

cdtaylor51 (author)  mark.buttle11 month ago
I am not sure what you are asking me here. I reread what I wrote and I don't know what else I could add to that. Here is where I got my relay modules:

They are just relay boards that are controlled with 5 volts and can switch up to 24 volts DC or 120 volts AC. You can get more information on their Wiki page here:

I replaced the 3-pin header on each module with a polarized locking connector that I had.

As I said, you can do whatever you want or need to do with the relays. I connected them to the functions that are broken out on the CNC controller board. If you needed to do something else then you certainly could but I believe that those are the functions that Grbl is expecting. You could also connect any of the relays to an external solid state relay to control a higher power device.

One thing that I do not yet understand is how to deal with variable speed spindles. The connector that I used for the spindle functions has eight pins, and I used six, so adding additional functions or features should not be too difficult. But I don't know how the Grbl guys are going to bring that function out yet either. There are new versions of things all the time.

I hope that this is what you wanted to know. Thanks for your comment and for reading about my controller.
cdtaylor51 (author)  cdtaylor511 month ago
I just looked at the relays again. The relays get +5V and ground from the power distribution board. The relay control signals are in the white expandable sleeving and connect to the CNC controller shield. I then tied +12V from the power distribution board to the common pin of each relay. Then the normally open pin is connected to the "S" connector. Then I connected ground from the power distribution board to the "S"connector too. I could have tied all of the grounds together and just ran a single ground wire to the "S" connector but not doing so allows for more current and more modulatity. I could have also gotten ground from the CNC controller board but chose to get ground from the power distribution board instead. The pictures don't show this very well. I hope this helps. Keep asking questions and I will keep trying to give good answers.
Sekai1 month ago

nice cnc controller. and very compact.Do you perhaps know how to connect a raspberry pi with a standart paralel port.I have a cnc machine (router) with L297-L298 combination, and i am using an old pentium 4 pc, but i want to make the cnc more i was thinking of doing with a raspberry pi.

cdtaylor51 (author)  Sekai1 month ago

I think that I misread your comment. One of the reasons that I built my CNC controller was because I was, like you, using an old Pentium based computer because that was the only machine that I had that had a parallel port. That's fine if that is what you want to do and LinuxCNC works very well in that environment but if you want more latitude and to be able to do other things then this environment is very limiting. So I built a completely new controller based on a Raspberry Pi and an Arduino. I have not tried to use an RPi as a parallel port adapter. Here is another situation where the RPi is running Wheezy, which is a time sharing, multiuser, operating system but you would really be better off using a real time operating system. Try Googling "raspberry pi real time os" or "raspberry pi parallel port". My solution completely eliminated the parallel port from my CNC machine and now I just use a wireless connection from my laptop to my CNC controller (RPi). I could also use an Ethernet connection if I wanted to but the wireless connection is just a lot more convenient for me.

cdtaylor51 (author)  Sekai1 month ago
I believe that I addressed this topic before but the way I see it you would need some way to get the higher voltage and current to the stepper motors. Other than that I am pretty sure that the RPi can handle everything else. However the bigger issue is the software and that would take a big effort to create. That is why I did what I did instead. Please see the other comments for more information. Thanks for your comments.
BertieS11 month ago

Nice would you be able to link to any resources for building the rest of the machine? Thanks

cdtaylor51 (author)  BertieS11 month ago

I am not a sponsor of any make of CNC machine. This is a really hard question to answer. I do not know what you intend to do with your machine and this controller is able to control pretty much any 3-axis machine. You could, for example, make a laser engraving machine with this controller. I am not sure what sort of machine you want to get into. Personally, I purchased a 3-axis CNC milling machine from MyDIYCNC when it was a Kickstarter project and paid about $500.00 for it. You can look at their site if you like. I believe that their current offering is much better than the one that I purchased. (They offered me an upgrade for $250.00. I have not done it yet but might. I have made some big changes to my machine because I was not able to accomplish what I wanted to do with it but for what it is its okay). I am also impressed with the shapeoko offering. I believe you can get a machine from either place with or without electronics. If you do that and build a controller like mine you would still need to have stepper motors and limit switches. The two machines are really different in their approaches to motion control. The MyDIYCNC machine uses threaded rods that I believe are inherently not very accurate and they also use their own anti-backlash mechanism that I do not believe is very good either (just my opinion). I have replaced the threaded rods with Hayden Kerk anti-backlash nuts and lead screws that are very accurate (about $50 per axis plus couplings). On the other hand the shapeoko offering uses belts instead of lead screws. A lot of machines have used belts in the past but I like lead screws better. I believe that belts stretch over time and that the machine will become less accurate over time as the belts age. But that is just my opinion too. I think that maybe the best way to go is to get a good, heavy, manual milling machine. Something like this for example:,9616.html And then add the CNC stepper motors and limit switches to it along with the CNC controller of your choice. Here is a website that shows how to convert a manual mini milling machine into a CNC mini milling machine. This would be a very nice, very stable, very accurate and repeatable machine and would handle pretty much anything you might want to do in a mini-machine shop. Lastly, look at this site for more information about everything that has to do with home / hobby size machine shops: The more you learn about how all of this CNC stuff works the better you will be able to choose a machine that will do what you want to do with it. Remember that there are also CNC controlled lathes, milling machines, engravers, cutters and even 3D printers (since I published my instructable I have learned that my controller won't quite do all that is needed for a 3D printer. You really need at least 5-axes for that). Grbl only supports 3-axis machines. Good luck, I hope this answer helps. If any one else wants to comment on these ideas please do so.

phuketbot2 months ago

what you realise chang a lot of think about home cnc ,distant control and distant fix ,price , control cnc not in the noisy same room.......

it for that try to do the same, i have a lot of difficult to preparre cart programme; nobody who have realise the cart can upload the img of the raspberry cart per torrent to make the work in some simple clic.

cdtaylor51 (author)  phuketbot1 month ago

There is a good tutorial on building the Raspberry Pi software on the Adafruit site.

Try this:

Make sure that you have SSH installed first. Also I had a couple of questions and they got back to me right away. Took a LONG time to install Cygwin (SSH) to work with this process.

CharlieZed2 months ago

Great work!

I was wondering if you could provide a circuit diagram for the Power Distribution board in step 8?

cdtaylor51 (author)  CharlieZed1 month ago
I have attached a simple schematic showing how the switches and leds and the Power Distribution and Inverter Board is wired. I hope that this it makes it easier to understand. The connectors on the left side of the schematic get connected to the CNC Controller board. The CNC Controller board provides the four function pins and a ground for each function. Only four of the six inverters in the 7404 chip are used. The connectors in the middle of the schematic represent the 12 pin header that is on the Power Distribution Inverter board and is connected back to the four switches too. The +12V and +5V parts of the schematic represents the power distribution buses on either edge of the board. I connected the power from the external power supply to the rails. I then connected the+5VDC from the rails to the RPi and the Alamode. Followed by connecting the +12VDC to the CNC Controller. Then finally I connected the ground pins for the spindle signals (the three relays) to ground. Again the +12VDC ground is connected to the +5VDC ground. +5V is also the Vcc for the Hex Inverter chip. Let me know if you find anything wrong with my schematic. Good luck on building your own.
cdtaylor51 (author)  CharlieZed1 month ago
Thanks for your comment. I thought about a schematic for the power board but it was so simple I didn't do it. You can print big copies of the pictures (both sides) and just build an exact copy of what I did if you want. I will add a schematic in the next couple of days. There is a small schematic showing how the switches and leds are connected that I included in a previous reply too. That might help in the mean time. The other things on the board just simply provide power to different things. There is a +12VDC rail on one side and a +5VDC rail on the other side. Then the grounds are tied together. That is really all there is to it. As I said I will post a schematic in the next few days. I am really busy right now.
cdtaylor51 (author)  cdtaylor511 month ago

Here is the little schematic about how the switches are wired to the functions and to the Hex Inverter (7404 chip) and the leds that are in the swiches. I hope this helps until I can do a complete schematic of the power board.

joaoji3 months ago

Very good your work, worthy of a good teacher!

Could you post a video on youtube of your CNC showing some details mainly featuring the g-code transfer process for processing?

cdtaylor51 (author)  joaoji3 months ago

Well, I am not in a position to do a video so here is an explanation about what is going on with the software.  I made a few assumptions that I guess I should not have made.  Hopefully, this will clear things up for anyone who is confused by what I previously posted.     In Step 13: Testing, I showed how the software works.  As I said, I used Remote Desktop to connect to my Raspberry Pi from my laptop. 

1st Picture:

The first picture that has a large raspberry in the middle of it is the desktop of my Raspberry Pi.  Notice that is just shows a few icons.  Notice that one of the icons is for the GrblController.  To test the system I clicked on the GrblController icon which brought up the GrblController window that you can see in the next image.

2nd Picture:

 In this image you should be able to see that the Port name is populated with the name of the port that the RPi is using to talk with the Arduino/Alamode.  It should be ttyS0 and the Baud Rate should be 9600.  If all of this is right then you would next click on the “Open” button to establish a connection between the RPi and the Arduino/Alamode and that will take you to the next image. 

3rd Picture:

The text on the Open button will change to “Close/Reset” and the button will go red.  Notice that the Port name and the Baud Rate are greyed out and cannot be changed at this time.  Once the connection between the RPi and the Arduino/Alamode is established the GrblController will automatically send a message to the Grbl Interpreter on the Arduino/Alamode and the Grbl Interpreter will respond with the information that you see in the window under the Command box.  You can get the Grbl Interpreter to send that information again if you enter $$ in the Command window.  Notice that anything sent to the Grbl Interpreter is preceded by a right arrow symbol “>”.   The system is now waiting for something to do. 

You can use the arrow keys in the Axis Control window to move the desired axis of your machine or you can go to the advanced window to manually enter Gcode commands or you can go to the Visualizer window (more about that later) or you can select a design file that contains Gcode. 

4th Picture:

I loaded a design file that I made with makercam (see the introduction).  As you can see I chose a design file the ends with the .nc suffix.

5th Picture:

 In the next picture I clicked on the Begin button.  That causes the “Choose File” and “Begin” buttons to get greyed out and the “Stop” button is now available.  The visualizer will automatically show you what the design will look like.  Notice that the image of the “T” is blue and the machine and work coordinates are all zeros (before the Begin button is clicked). 

6th Picture:

The next image shows more data in the window on the left.  Notice that Gcode commands are showing up in the list.  Also notice that a statement telling you that the GrblController is “Sending” a file to the Arduino/Alamode/Grbl Interpreter.  Also you should notice that the Queued Commands bar is showing some depth.  This is because several Gcode commands have been queued up for execution.  Further, the Machine and Work coordinates have changed and they are no longer zeros.  Lastly note that the image in the Visualizer window has some green lines that are replacing the blue lines.  This shows you what segments of the design file the system has completed and where it is currently working.  As work progresses through the design file the lines will continue to go from blue to green and the coordinates will continue to update and the lines in the information window will continue to appear.  You can click on the stop button anytime you want to interrupt the system.   You can see that eventually all of the blue lines have been replaced by green ones indicating that the design file has been completely processed. 

7th Picture:

Finally in the last picture, after the design has been completed the system moves back to the origin and the coordinates go back to zeros and the design is finished.  Now the system is once again waiting for something to do. 

vtstruct4 months ago

Very interesting project, thanks for posting this!

A couple questions:

1.) if I already have individual commercial stepper drivers, can I eliminate the shield board?

Does GRBL provide look ahead buffer capabilities for motion control --
how square would corners be if this system was running a mill, and does
the feed rate slow down from a straight line on doing arcs an circles
made of polylines?

cdtaylor51 (author)  vtstruct4 months ago
There are many ways to drive the stepper motors. As for information about GRBL I would suggest that you contact the GRBL authors. I am a relative novice and still don't know as much as I need to know and I do not feel confident in answering your questions. Thanks for taking a look at my project.
cdtaylor51 (author)  cdtaylor513 months ago
You would probably want to use an Arduino prototyping shield to provide an interface between the Arduino and you drivers.
EricP53 months ago

Well Mr. Taylor after reading your instructible I have FINALLY
decided to take the plunge and build a CNC. I have the plans, about 96%
of the parts, and have been working with the Arduino/Raspberry PI boards
for a year or so now. I guess, after reading through your instructions,
I have a few questions that I am somewhat fuzzy on

1) You mention
a power distribution board but I don't recall if that is a part that I
need to purchase or make. If I need to make it is there a schematic

2) It looks like I maybe misunderstood how the
Raspberry PI works with the Arduino... I thought that I needed to run
LinuxCNC as the OS on my PI and then control or send the Gcode to the
Alamode via the GPIO so that the GRBL would intrepret it and then send
the stepper motor instructions to the CNC board. Do I NOT need to use
LinuxCNC? If not how do I send the Gcode to the Alamode - via the IDE?

questions posited I have to add on to the choir that this is an
excellent and well thought out instructible and your end result was
elegant. Hell, it impressed me enough to finally get off of my butt and
get this done. Plenty of folks would tell you that is a feat in itself.

cdtaylor51 (author)  EricP53 months ago
The power distribution board that I mentioned is not completely necessary but just a convenient way to get power where I want it and I also put the hex inverter that I used to drive the LEDs on it. You obviously do not need to have illuminated switches either. The power distribution function is really simple. I just used the power rails on either side of the board to pick off the power where I needed it. The rails are on either side with +5V and ground on one side and +12V and ground on the other side (with the grounds tied together). I included a small schematic showing how the switches and LEDs are wired up in a previous comment. Take a look at the other comments. They present some good information too.

As for the software I used: GRBL is implemented by putting the GRBL interpreter on the Arduino (Alamode in my project) and the GRBL Controller on the Raspberry Pi. I am not using LinuxCNC at all. I would refer you to the GRBL authors if you want to use the interpreter in a different way. The screenshots in the last step show what you would see on the screen of the RPi while running the GRBL Interpreter on the Arduino and the GRBL Controller on the RPi. You would need some other piece of software to make a design file to process with the GRBL software.

I hope that makes things more understandable. Good luck with your project and thanks for looking at mine also thanks for the comments too.
DanB74 months ago

Cool!...I multiplied every long word by 10 minutes as I read....Impressed but I think I have to find a quicker solution - I have only so many years left and need to get my project up and running too......I am working backwards from the steel frame.....and have a long way to go (further now than I first envisaged..;-).) But thank you especially for your organisational skills.....

cdtaylor51 (author)  DanB74 months ago
DanB7 - I am not sure what you meant with your first sentence, maybe you could clarify that and then I might be able respond. if there is anything that is mot explained well enough let me know and I will try to help. Not sure what the second sentence means either. I guess you believe that my instuctable is too long. Working backwards from a steel frame might mean that you have a machine with a steel frame and you are now looking for a controller for it but I am not sure as the context does not provide any way to know for sure. If that is the case then you could simply purchase a CNC controller system through ebay or elsewhere on the Internet and completely skip building your own. This instuctable is my first attempt to put something like this together. It was meant to help others who might want to do something similar and it is just the way I did it and did not intend to restrict anyone from doing something differently. It also shows some of the prototyping techniques that I have learned and used over the years. My hope was to help others to raise the quality of their projects to a higher level that they would be happier with. I am still learning too. When I read through an instructable about something that I have not done before I always learn about things that I previously did not know. Sometimes the learning curve is high and it is difficult to understand. I am always grateful to learn more especially about things that I knew nothing about before. I hope that my little instructable has added a bit, and elevated the journey's of, the more than 100,000 people who have read it. Thanks for your comments and just ask if I need to explain something better and I will do my best to do so. Please be as specific as possible and I will do the same.
DanB7 cdtaylor514 months ago
I am in awe at your knowledge, learning and application. You must have spent a long time on it. Your clear words must have been magnified 10 fold in the actual application of your knowledge. I am very impressed by your result but doubt I could emulate it and may have to initially think "simple" to start with.
cdtaylor51 (author)  DanB74 months ago
Well DanB7, I believe you could do this too. Just take one step at a time. Get all of the parts and tools that you need and take you time. I recommend that you start by getting the software working on the Raspberry Pi and the Arduino/Alamode. Then add on the 100% GRBL Compati le CNC Controller. At that point you could temporarily attach you stepper motors and verify that everything works as it should. Then you can start thinking about packaging everything. Thatis really what instuctable is abou. Use expandable sleeving to bundle wires together in a logical way. Expandable sleeving needs to be cut with a hottool to melt the fibers together but further you need to reminate the expandable sleeving with heat shrink tubing. That will help to hold the sleeving in place and protect the ends too - it also looks better. You need to be careful though because you can easily melt the pin housings by getting them too hot (read, voice of experience here). Putting the holes in the box and making the carrier plate were the hardest parts because I had to do those things by hand with my Dremel tool. Read the other commentsfor more info about that. I am sure that youcan do it. Thanks fir your comments.
cdtaylor51 (author)  cdtaylor514 months ago
I read my reply twice to make sure there were no typos, etc. Then posted and read again and there are typos. What can I say?
dgaynor5 months ago

Why didn't you use the 12-36V stepper power supply on the GRBL board? Aren't the stepper motors going to be under powered now?

cdtaylor51 (author)  dgaynor5 months ago
My stepper motors are all 12 volts and so is my spindle. Changing the wiring for other voltages would be pretty easy to do and the CNC Controller board is already able to handle 12 - 36 volts.
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