Last modified December 1, 2020
For a long time I wanted to build a Homemade and cheap CNC, if possible with 3d printed parts, with a Arduino as a controller.
In my head I imagined doing thousand and one projects for all my hobbies: printed circuit boards for electronics, pieces of wood for my planes of model airplanes, and carbon fiber parts for drones, doing the box machining for electronic projects, panels, etc.
After several years with this recurring idea, in the summer of 2017 I decided to take action and build the CNC (or numerical control milling machine) that I present here.
How to do everything in a single blog post can be very long and tedious, and I intend to get to a certain level of detail, include Photos and all the tips that seem important to me that you remember when I built it, I am going to divide it into several entries, that I will be writing little by little (do not forget subscribe to the Blog to find out when they are published):
- Overview and options
- Milling or Spindle (Mandrel)
In this post, overview, I am going to talk about how is it and of the cnc capabilities in a very generic way.
This is a cheap to build CNC milling machine, with a linear motion system done with bearings, the kind that are usually used on skateboards, which slide on square aluminum or steel tubes.
This linear motion system has the advantage that it is precise enough for normal jobs that are not precision (if I wanted to mill a one euro coin in my CNC I will tell you that it would lack precision) and it is much cheaper than the thrust bearings on rods or linear guides, important when you want get a cheap CNC.
Overview and options
When I started to think about building the CNC milling machine my head was a pressure cooker, full of doubts and questions.
There is a lot of information on the internet, but when you have no idea, as was my case, you can have it right under your nose and not recognize it.
Things like what I would use it for, the effective job size I wanted to achieve, the general format of the CNC, whether to use professional parts (such as linear guides) or all homemade construction, etc. I was clear that I was going to use it to mill wood.
There are many options, and I am going to review them here because it would be very long, but I can say that after a long time looking at years! I found the design that I liked.
The design was called Root CNC, a homemade CNC milling machine design with free plans, and it was made on the basis of cheap and easy-to-find materials, printed parts, wood, iron tubes ... Electronics, similar to that of a 3D printer: an Arduino, stepper motors and little else ...
The aspect of the mechanics of the CNC is this:
The mechanical part is made with tubes of 20x20mm aluminum or steel , which can be bought at Leroy Merlin or similar, skateboard bearings, 3D printed parts on the 3D printer (many parts, Almost 3 Kg of PETG filament!) and bolts and nuts (Lots of nuts and bolts!).
For the tubes I used 1.5mm thick aluminum (which you can find from Leroy Merlin) but they flexed on moderately hard jobs so I swapped them out for 2mm steel whenever I could.
Those would be missing pieces of wood which, at first, I made by hand with MDF and, when the machine was already working, one of his first jobs was to machine your own final pieces in phenolic plywood which were great.
One tip: if you make them by hand make sure that everything is well square, when cutting them and making the holes (which are many). If everything is not square and in place, then the work you do they won't go well. Ideally, someone will do them with a CNC machine. If not, do what I do, the first ones by hand, the best possible, and as soon as it works "the good ones".
The electronics for the Root CNC are also very simple and cheap. It is very similar to the electronics of a 3D printer.
It consists of a Arduino, like brain, some drivers, which are what makes the Arduino capable of controlling motors, and some stepper motors.
The power of the stepper motors and their corresponding drivers must be chosen based on what is intended to be done with the CNC. The same motors can be used, Nema 17, from 3D printers (enough for "light" jobs, engraving on soft woods, printed circuit boards, working with plastics, etc.) or using ones with more power, type Nema 23, if you want to do things with hard woods, cutting jobs, working metals like aluminum or brass, etc.
In my case I have used Nema 23 motors with DM542A drivers. This set has enough power to work any type of wood, no matter how hard it is, plastic such as methacrylate (also called acrylic), metals such as aluminum, and other materials.
If you do not want to install such powerful motors and drivers, a good option is to use a board called CNC Shield with normal 3D printer drivers such as the DRV8825, this greatly reduces the cost.
Of course, it would be missing a power supply and other minor accessories.
- ❤️Last for Arduino CNC Shield Version 3.0
- ❤️For Arduino with R3, 2.8 inch LCD touch screen, MCU: ATmega328, USB interface: ATmega16U2
- ❤️PWM Spindle and steering pins. 4 axis support. 12 to 36V DC power supply
- ❤️2 stops for limit switches for each axis (6 in total)
- ❤️4 A4988 Stepper Motor Drivers
This well-priced Amazon kit includes the Arduino, the CNC Shield, the DRV8825 drivers and even some limit switches, which can come in handy.
These Nema 17 engines are pretty good. They have a power of 0.45 Nm. Beware of catching the model QD05 and not QD06 that appears on the same page and has a lot of less power.
- NEMA-17 Stepper Motor 64 oz.in (0.45 Nm), 38mm Body, 1.8 Degree with 1M 4-pin Cable and Bracket Kit for DIY 3D Printer CNC Robot.
- 1M cable, one end connects the electric machine, the other has many optional ports to choose from; The effect of thermal shrinkage to prevent the cable from coiling.
- 90 degree bracket (L Type) with M3 screws.
- 1M 4-pin Cable with Insulated Sleeve - Detachable, for easy installation.
- 64 oz.in (0.45 Nm) holding torque. 1.8 degree step angle (200 steps / rev.)
Milling or Spindle
The milling machine, spindle, or motor is one of the important parts of the CNC.
We basically have three main options.
- Hand Multitool
- Milling machine
- High frequency motor and inverter
This is the type tool Dremel or similar.
Its main advantage is the price (not that much) but it doesn't have much strength and makes a lot of noise. They are also not intended to run for long periods of time.
In my opinion it's not worth much Unless what you want to do with the CNC is limited to printed circuit boards, light wood engraving, plastic engraving and the like.
A good milling machine is a working beast, but it has a big problem: it makes a hellish noise.
I started, for economy, with a milling machine very similar to the Makita RT0700C, a 710 Watt milling machine and I it worked very well, even though I ended up not putting up with the noise.
High frequency motor and inverter
In my opinion, what they usually call spindle, the high frequency motor with inverter (VFD), is what a CNC should have, the rest are fixes.
I, after two years with the milling machine, put a spindle of 1.5 kW water cooled And I wouldn't go back In the photo I leave you the one I bought.
What are the advantages of a spindle?
- Makes no noise. When it works empty it sounds very little. The noise that is generated is really what the cutter makes against the material being milled, the engine hardly sounds.
- It can regulate speed, even by software, and that is important.
- You can work hours and hours without flinching.
- It seems silly, but it is not at all: as it is water-cooled does not expel air (as do milling machines, Dremels and others) with what no sawdust comes out, or the chips of the material you are working with, shot all over the garage ?
- Lets put a huge variety of types and sizes of strawberries.
Building the CNC Root 3 has been a very nice and interesting project, and it's amazing what you can get to to learn.
Is not difficult, it is simply a matter of going step by step and with patience.
If you liked the article, I will be very grateful if you spend a minute in leave a comment below.
One last trick. Sometimes I use a foot pedal, like the one you can see below, to be able to quickly pause the CNC, when necessary.