CNC mills are computer-controlled milling machines that can create custom 3D objects from a block of solid material. Roland advertises their CNC mills as "subtractive rapid prototyping" devices, thus similar in philosophy to "additive" 3D printing rapid prototyping. The benefit of mills over 3D printing is that one can create objects out of a wide variety of material, including metal. Another added benefit is the ability to cut and etch PC boards for electronics. It can even be used to make two-sided SMD type PCBs.
CNC mills can be a DIY project, a retrofit to a manual mill, or a ready-to-run appliance. The CNC component is composed of motors driving each axis (x,y,z,a). These motors can be stepper or servos. Some have additional encoders to improve accuracy or provide better feedback. This is termed as closed-loop feedback. Typically, lower cost CNC are open-loop and rely on the high resolution of the latest stepper motor technology.
The CNC control also requires a controller or set of controllers to run the motors. Typically, controllers connect to a computer through the parallel port. And software is required on the computer to translate G-code into controller actions.
A CAD and CAM program is required for design, stl file, and g-code generation. CAM software typically reads in STL file formats and allow for visual simulation of tool paths. STL files are slices of the part represented as a series of triangle faces. So a good program will convert this with high resolution into G-code and include tool changes.
CNC Mini-Mills are typically used to cut wax, plastic, steel, aluminum, and copper. Many DIY setups have a wet-dry vac setup piped right next to the cutting edge. Others might use compressed air to blow cuttings off the part. For cutting metals, there is a need for flood or mist spraying of the cutting edge to act as a coolant and lubricant. So many cnc setups have a pump, liquid collection area, and enclosures setup to deal with the mess and reclaiming/recycling of the liquid. CNC controllers can be outfitted with a relay to control the pump.
Mills use collets to hold the cutter. These cutters are called end mills, ball end mills, thread mills, etc. End mills are best used to cut in a horizontal fashion. Center-cutting end mills can be used in a plunging manner. Also drill bits can be used for that purpose. End mills commonly have 2 or 4-flute cutting edges. Ball end mills are have a rounded cutting edge pointed downwards. It is used for fine contouring. Thread mills are used for cutting threads and utilize CNC in a cutting fashion called helical interpolation. This has many advantages over typical threading done with tap and die. More info on cutters can be found here. Some cutters are a combination drill and thread mill (sample video).
See also the Metal Working page.
CNC Machines, ready-to-run
- Roland Modela MDX series
- Novakon makes a good one for $3-4k (lease $60/month), the NM-070
- Alex Chang got his Taig through Super-Tech
-
- Mini-mills are based off three platforms: Sieg/Harbor Freight KX3, Taig, and Sherline
- These are 4th and even 5th axis capable (sample video) which allow for rotation of the part at the same time it is moving along the x,y,z axis. Typical cost of adding a 4th axis is $600.
- Minitech Machinery has high-precision machines
- Tormach has two cnc mills, a cnc lathe and accessories
- LittleMachineShop.com (in Pasadena) sells KX3 based mills
CNC Milling Materials
CNC Resources
Local CNC/Machine Tool Vendors
Milling Accessories
CNC Motor Controller Hardware
CNC Motor Controller Software
CAD Software
CAM Software
Enclosure Hardware
Translating Eagle files to G-Code
Comments (0)
You don't have permission to comment on this page.