A lot of people have looked at CNC machines and thought they would let them do something faster, more accurately, or let them do something they couldn’t do by hand.These are great goals, and they are achievable, but like everything in life, there are tradeoffs.

 First of all, I would like to say that there is a big difference between having a CNC machine and programming it and running it.It sounds simple enough, but many people fall into this trap.This machine is not magical.It won’t know anything you don’t know.It’s up to you to decide how to create the parts, then program and test the machine.Sometimes getting a CNC machine to do something is much more difficult and takes more time than doing it by hand.

 First, consider carefully whether the CNC machine can cut the parts you want to make.The 3-axis CNC machine moves the rotating tool in three dimensions while making the tool perpendicular to the working surface.Can you do this, or do you need to tilt the cutter?(There are 5-axis machines that allow tilting, but they are much more expensive.)

 Can you do your job by cutting one side, or do you need to flip it over?If so, how do you ensure that the parts are properly placed when you rotate them?How are parts held during machining?Can you clamp, screw, or glue the parts to the workbench, or do you need vacuum adsorption?Do you need more than one tool to make the part, or just one?Next, consider how to program the machine.The first step is usually to draw the part in a computer-aided design (CAD) program.Once this is done, you need to create the tool path, specifying how the machine moves the tool to create the part.This is called computer-aided processing (CAM), which is why you often hear the term CAD/CAM.

CNC machine tools are great for many things.I use the following:

 1. Cut the core of the ski.Accuracy is king here.The effort to program the machine is well worth it, because honestly, even using templates to help you, you won’t get the accuracy you need.

2. Cutting mold parts.These are simple shapes, usually cut into 3/4″ MDF, but I usually need 21 of each.While I was at the store doing other things, it was a big win to take the time to make a program to cut 21 out of a single MDF sheet.

3. Create table saw zero clearance insert board.I make these out of beautiful Baltic birch plywood, 4-6 at a time.I spent an hour measuring and programming the plates that came with my table saw.Now I can make more of these disposable items anytime, anywhere.I can have some ready in about twenty minutes.

4. Complex one-off items, such as ornate wall supports, used to cut other shapes of templates, etc.Again, these are worth it in the end due to the complexity of the shape.I usually start them in a CAD program, and if they are two-dimensional, it usually makes sense to convert them into a few simple tool paths and let the machine do the cutting for me.