G300 - 3D Printed CNC Machine
Introduction: G300 - 3D Printed CNC Machine
About 6 months ago I started designing a cnc machine that allowed me to carry out some milling works; the design phase was very demanding in terms of time because it involved both the mechanical and the electronic parts.
I decided to call this machine G300 because € 300 is the overall spending target that I set myself, which I was able to meet. I intend to use the G300 mainly on wood and plastic sheets (PP and PE) but I believe it can also be used for aluminum.
Step 1: FRAME DESIGN - PRELIMINARY CHOICES
INSPIRATION
Before starting I analyzed some of the existing projects and I particularly appreciated the works of <PERSON> and <PERSON>, whom I thank for the contribution they have given to the world of open CNCs and for having given the community some beautiful projects from which, I too was able to draw inspiration.
DESIGN AND STRUCTURAL CHOICES
In the creation of my proposal I was inspired by existing solutions and I evaluated each component with my personal ranking of importance:
* does it allow me to meet the target budget?
* is it an optimal solution?
* is it strong enough?
* does it have adequate reliability and durability?
I have therefore roughly established the characteristics of my CNC, which will consist of:
* Frame with 2040 aluminum profiles;
* 625ZZ V-Slot wheels;
* GT2 fiber-reinforced belts;
* Lead Screw for the Z axis;
* 3D printed elements in PLA;
* Arduino with GRBL;
* Nema23 motors with TB6600;
* Katsu router (Makita RT0700C clone);
OVERALL DIMENSIONS AND WORKING AREA
For my applications I was interested in having a working area of about 600x450mm and a vertical excursion of about 60mm; the overall size of the CNC (excluding the electronics box) is about 1000x800mm. In case you require a different working area, keep in mind that the aluminum profiles in the X axis must be longer by at least 130mm of the required size, while in the Y axis by at least 160mm.
Step 2: DESIGN WITH FUSION 360
FUSION 360: FRAME DESIGN
I have been using Fusion360 for hobby purposes for 5 years now and it has been of help to me on numerous occasions; therefore I chose it to make the G300, modeling in detail every single component necessary for the creation of my CNC.
https://www.autodesk.com/products/fusion-360/perso...
The feature of Fusion 360 that I liked right away is the simplicity of the tools available, their potential and the graphical interface cleaning. There are also a number of modules that accompany you throughout the creation process: concept with sketches, 3D solids, mechanical analysis, render, and physical creation with the CAM.
The geometry I have chosen is quite square and regular; therefore also the modeling tools are simple and basic: sketch, extrude, stretch, move / copy, fillet, drill. 737
Despite the relative simplicity of the controls, the design phase took several hours, obtained from my free time in a span of about 6 months; the revision of the pieces took me a lot of time as I tried to optimize every single element as much as possible. Optimized design involved: functionality, strength, and finally I tried to give a personal touch to what I had designed.
FUSION 360: THE COMPONENTS LIBRARY
The three-dimensional model was then completed using the McMaster-Carr library, already included in Fusion360, with a vast assortment of small parts that allowed me to insert all the screws, bolts, nuts, washers, etc.
The few objects not available, or with dimensions not adequate for what I needed, I found them through the free library of www.GrabCad.com With a three-dimensional model, precise down to the tiniest detail, I was able to analyze every single element and make the appropriate changes since the design stage, eliminating the need for a preliminary prototyping.
Step 3: CUSTOM ELECTRONICS
I am currently developing a custom electronics for the G300 management which consists in the coupling of two separate Arduinos. The first manages CNC operations using GRBL software while the second is dedicated to managing the spindle speed.
In particular, the second Arduino reads the required spindle speed from the TX port of the GRBL and compares it with the real one, measured by an IR sensor, and makes sure that the speeds match using a PI / PID system. It also takes care of the emergency stop of the CNC in case errors are detected (send STOP signal to Arduino GRBL). 737