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How To Build A Cnc Mill

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Hobby Mac

Mar 17, 2013

Tools that rely on computer numerical control, or CNC, setups can accurately produce prototypes and projects from a set of plans entered into a computer. CNC mills quickly carve through wood and other materials to produce three-dimensional shapes, and some systems can deliver exceptionally detailed models and pieces for other projects. Building your own CNC mill takes some time, but it can dramatically cut down on the costs of purchasing a new premanufactured version.

Locate and Print a Pattern
Locate or purchase a pattern for the parts for your CNC mill. Patterns for these milling machines should include exact measurements for each piece as well as designs that you can print and place on MDF wood or plastic to create the essential components of your machine. Use a high-quality printer to print the patterns full-sized for accurate results, or pick up a set of plans that include preprinted patterns, along with instructions for specific components.

Cut Out the Pattern
Use a high-quality adhesive to stick the pattern pieces to the composite wood or plastic sheet you plan to use for the CNC mill parts. Take care to ensure the pattern pages lie completely smoothly over the surface of the material. Wrinkles in the pages can dramatically affect the final dimensions, resulting in pieces that require reworking or replacement during assembly. Carve the pieces out of the pattern using a jigsaw. Do not remove the pattern from the cut pieces at this stage.

Drill Holes
Use a high-powered drill to create holes with the diameters specified on the pattern at each spot shown on the pattern. Since the pattern pages should still be adhered to the sides of the pieces, you can drill directly through the sheet and material to create places for screws and bolts. Take care to keep all holes as straight as possible, especially if you are using plans that only include one sheet of preprinted patterns. Use a light solvent or warm water to remove the remaining pattern material after you finish drilling all of the holes.

Assemble the CNC Mill
With the pieces completely cut and drilled out, assemble the parts using the pattern. Most patterns and plans call for a wrench and screwdriver, at minimum, to complete assembly. Remember to bolt in the motors and controllers that move the mill and interact with the software as well as any additional components called for by the plans you select. Most CNC mills operate on a three-axis system, which allows for modification of height, width, and depth. This means that most systems also require multiple motors and milling components.

Add Wiring and Configure
Attach the wiring and connectors as required by the motors and moving parts of the plans you use. Install the CNC software on a nearby computer, and configure the setup based on the instructions for the software. Many CNC systems have single, plug-and-play setups that connect to specific components installed alongside the motors, and available motors and plans may suggest specific operating programs or connector types for the best results. Upon assembling and configuring the CNC mill, run a test set of plans through the system to determine its accuracy, and make adjustments to the configuration as needed.

How to Buy a CNC Mill on eBay
Purchase a premanufactured CNC mill or the parts you need to build your own on eBay. Search fields deliver accurate results for many crucial parts and systems, and you can use the search filters located on the left side of each results page to quickly narrow options by price or auction type.



Active Member
Active Member
Jan 25, 2015
I researched building my own CNC Mill for a long time before investing the money and time to start. The term "MILL" is used very loosely when it comes to CNC. I see a lot of routers and engravers being termed "MILLS" and I guess they are but when I hear the term mill I think of something that can cut steel usefully.

CNC Mills can be simple conversions or complex build ups. They can have lots of features or simply run three basic axis. Features include 4th 5th 6th and so on axis, tool changers, auto-coolant, limit switches, probes etc.... You really have to decide what your budget and skill level can accommodate.

At the very basic level you will require One stepper motor, One Power Supply, and One Stepper Driver. This would give you a single axis of motion but you are going to need at least three axis, thus you need three of each. Then you will need a CNC controller that connects to a PC.

That is just the electronics, you have to have a motion system for each axis, usually a lead screw and some sort of anti-backlash nut or ball screw. I like linear motion rails myself for larger mills that are going to be used to machine steel.

The CNC mill I am building is running around $3000.00 in parts. I made my own spindle and used a lot of surplus parts found here and there. I am also including features like limit switches, Spindle air chuck, auto coolant and PWM spindle speed control. Each of these add on features has increased the price and build complexity. I however think they are worth it.

All this neat stuff has to be mounted on something. Most of us do not have the ability to cast large bases and columns like that used on a Bridgeport mill. We still need the weight and rigidity so what can we do? I choose to use Steel square 2" structural tubing for my mill. There are a lot of ideas out there but it needs to be hefty.

So you get everything together, mechanical and electrical but now you need software. Every CNC device needs controller software that sends signals to the CNC controller, MACH3 is one popular software at around $175.00
You are also going to need Computer Aided Drawing software or CAD to develop parts on, then you need CAM software to convert the drawing into tool paths (GCODE) your controller can use to make parts.

The learning curve is straight up and the cost really piles on. You can do it but go into it with eyes wide open.

There are things that can surprise you, like the spindle, I built my spindle on my lathe but to buy one like I built would cost in excess of $2000.00 I also built my anti-backlash nuts and used low cost ACME rod. I planned to build my own linear motion system but I was able to purchase all three pairs for $600.00 so I decided my time could be better spent elsewhere and the linear system would be better than anything I would create probably.

If you choose to build a CNC mill from the ground up you are going to do lots of welding, drilling, tapping and grinding. Long hours and tedious work are involved, at least for me. Everything has to be true, square and level before it is welded. CNC is all about precision.
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