First dust! My CNC machine is working in practice, not just in theory.

What a thrill! Picture me standing in my garage, wearing eye protection and a dust mask. I am watching my MPCNC chug away, creating 30 small pockets in a piece of MDF board. My kids might say “Dad. Get a life”.” But, this is it. Building a machine and getting it to work for the first time.

They call this “first dust”. The first time you actually make something with a CNC.

In my case, the first dust project involved cutting circular pockets or holes in the back of a board. These holes will be used to hold metal T-Nuts. These, in turn, will be used to secure work hold down clamps, which I am printing on my 3D printer. The steps in this project involved:

• Designing a 2D graphic of the circles, or hole boundaries for a single T-Nut pocket. This can be done in any CAD program
• Using the 2D graphic to assign machining tasks. In this case, it was a 3/4” circular pocket for the T-Nut base, and then a 5/16” pocket for the barrel of the nut. I also added a centered 0.25” shallow pocket so that I could line up my power drill to cut holes through the remaining board for the clamping screws.
• Generating the G-Code for the CNC machine control. Assigning the machining tasks and generating G-Code was done in EstlCAM, mainly using default settings. G-Code was produced for metric measurements in my CNC, even though the design was done in inches.
• Loading the G-Code into the CNC control software and running the job.

To do the work, I am using a rotary tool as a spindle. I am starting off with a bunch of cheap 1/8” carbide end mills or cutters. Mine are 2 flute up cut mills with a half inch cutting length.

First Dust, First Steps

As you can see in the video, my first dust was blue. I started by doing some practice milling in a chunk of Styrofoam, or rigid extruded polystyrene. After gaining confidence in what I was doing, I moved on the the real thing: MDF board.

MDF gives off quite a bit of dust, rather than wood chips. Having the central vacuum outlet in the garage makes it easy to capture dust during the work. For safety, I wore a dust mask, but between the vacuum and the small size of the job, the amount of dust in the air was limited.

The pattern of 30 holes took more than an hour to complete, using 3 passes. And yes, I stood there the whole time watching with fascination.