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JMIS Blog

Welcome to JustMakeItStudio blog. You can expect to see snippets of upcoming blueprints or freebies from the ones that are already available for sale.

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WHAT IS CNC MILLING?

CNC milling or machining in broader terms, stands for Computer Numerical Control. It's a manufacturing process that involves the use of computer-controlled machines to remove material from a workpiece leaving behind your desired shape.

These machines hold a cutting tool, often an endmill, that gets spun at high RPM by the spindle, and then moved in, commonly, 3 axis: left/ right, front/ back, and up/ down. These are called X-axis, Y-axis, and Z-axis respectively. This movement is performed with a high level of precision, allowing for repeated and tight-tolerance parts to be machined.

Of course, the kind of machine you are using will play a critical role in its overall capabilities. Some machines are made for light-duty electrical board tracing at credit card scale, while others are made to hog out toughened steel at container ship propeller scale at a rapid pace. Two companies that manufacture industrial CNC machines are Tormach and HAAS CNC. Now, for hobbyists, there are other affordable solutions like AVID CNC and VCarve, which pose limitations on material use and performance. And for the record, I have no relationship with any company mentioned here.

Moving on to the process, how do you CNC machine a part at home?

First, you need to design your part in CAD, or Computer Aided Design. There are a lot to choose from, some examples are Fusion 360, Rhino 3D, Solidworks, and Onshape. By using these programs you can create your part as a 3D model or 2D lines.  

Second, the shape you created is imported into another software called CAM, Computer Aided Manufacturing. Its job is to translate your shape into machine code, called G-Code, that literally translates into the movement of the cutting tool. To achieve this it takes instructions from the user like the CNC dimensions, tooling, and raw stock dimensions and location. Next, through a specific interpreter, it translates that into G-Code that is then fed to the CNC machine via USB or the internet. 

Furthermore, the selection of your CAM program depends on the type of work you are aiming at. If you will be creating 2 dimensional shapes, 2.5D objects, 3D surfaces, or carving letters, then your choice should reflect that. Quick note, a lot of CAD software have a CAM section already built in, but here is a quick list as reference: SolidCAM, Estlcam, RhinoCAM, SprutCAM, and VCarvePro.

Lastly, head over to your CNC. Start by securely fixing your raw material onto the bed of your CNC. Locate the starting point of your G-Code and zero your machine at that location. This is very crucial and depending on your machine this can be achieved using different methods. A hobbyist will probably bring the cutting tool so close to the workpiece that a piece of paper will not be able to pass between the 2. On the other hand, a professional may include a zeroing procedure in his G-Code that uses a tool called CNC probe that will automatically fill in the exact location of the raw stock and update the rest of the G-Code using those values. After that, you start the program and the machine will go to town creating your part in no time.

Some challenges include the initial setup and programming, as well as the need for skilled operators to ensure the machine runs effectively and safely. Despite this, CNC machining has evolved with advancements in technology, such as the integration of more axis and automation.

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