Having a CNC Mill in your shop is like having a voltmeter or SWR Bridge in line at the home station. Once a luxury, a CNC Mill is a commodity as the prices even with tariffs now places it on the affordable list. More on that later.
Many would think a CNC Mill is synonymous with circuit board fab, well, while true, initially I want to talk about uses other than homebrewing 7 transistor SSB transceiver circuit boards.
You have just purchased a Xiegu 6200 QRP Transceiver for POTA operation and now realize some accessories would be nice at the picnic table when you are in the US park. (About $800 just for the radio.)
Area Above the Tuning Knob = Internal Speaker
Self-Explanatory! You need a bigger Speaker.
Let us start with an external speaker for the radio. Yes, the internal speaker works well at the home shack but kind of "tinny sounding" in a large open space such as a park. You have a bargain 3" speaker found for $1 at a garage sale, but it is without an enclosure.
Speaker Box Sketch
Now what? Simple answer --- design a metal plate with a circular opening with dimensions to accommodate the speaker, fab a small wooden box from plywood and mount the speaker on the plate and then mount the plate to the wooden box. If you do things right the box can also be used to stash accessories you will need when doing the POTA dance. [YL's think: Lip gloss, SPF50 Sunscreen, pepper spray, cell phone battery charging pack and a couple of band-aids.]
Wow, your brain hurts because I went too fast. I keep forgetting that I have been CNC Milling projects for over 15 years, and I do some of this without thinking. So, let's start a square one.
Before you purchase anything (put the plastic away) you need to think about the CNC design system and that is a jungle out there. When I started out, I used a free design system called G Simple and it is very easy to use. But the output is a dxf file which then requires a 2nd conversion to G Code which is the standard directions format used by the cutting software like Mach III.
A different CNC design system is called Carbide Create which has the functionality to create the G-Code directly without the 2nd Conversion. I asked copilot about Carbide Create. It is free.
Can Carbide Create CNC Software be downloaded for free?
Yes — Carbide Create can be downloaded for free.
Carbide 3D offers Carbide Create as a free 2D CAD/CAM program designed for their CNC machines. Their official download page lists current and older versions available at no cost.
🧩 What “free” includes
Full access to the core 2D design tools
Toolpath creation and G‑code export
Simulation mode for previewing cuts
Windows and macOS versions available
Older versions (like V7) also remain free to download
💡 Additional context
Carbide Create is positioned as an easy‑to‑use CAD/CAM tool for CNC beginners and hobbyists. It’s lightweight, intuitive, and works well for woodworking, sign‑making, and general 2D machining.
Carbide 3D also offers a paid upgrade called Carbide Create Pro, which adds 3D modeling and advanced toolpaths — but the standard version remains free.
Once I create a program in Carbide Create, I set the cutting depth so that it will take several passes to completely cut through a chunk of metal. But there are some tricks to doing that, so each cut is precise and you end up with a clean hole.
Circular Hole Cutting. Multiple Pass!
When you call up the design page on Carbide Create it looks like a sheet of graph paper and that is a bonus as I layout my circuit boards using an actual piece of graph paper. So, what I sketch out on the real graph paper is simply transferred to the onscreen graph paper. It is the process.
Another approach with Carbide Create is to NOT create a whole PC Board design but rather "modules" like Band Pass and Low Pass Filters or ADE-1 SMD layouts. Thus, to put a BPF here on a PC Board--- just call up the BPF file, locate the 0,0 location and punch the start button.
Large Circular cutouts can be approached in 2 ways with the 2nd way the likely better choice. Suppose I wanted a 3 inch in diameter circular cutout and using method one on the Carbide Create, I would set the center point at position 1.5 inches on the X Axis and 1.5 inches on the Y Axis. The location at the lower left-hand corner is the 0,0 point. You ask Carbide Create to simulate the cut and a perfect circle is displayed that is tangent to the X axis at 1.5, 0 and tangent to the Y axis at 0, 1.5. Here is the problem on multiple cuts as you must always come back to the corner spot and set a depth so on repeated cuts you will have a deeper hole at 0,0.
Method 2 fixes that problem. You set the center at 0,0 on the X and Y axis and then repeat the simulation and you will see a circle which appears in 4 quadrants. Now the only problem is to initially locate the 0,0 point on the material to be cut. Lots of ways to find center. Draw lines from opposing corners and where they cross is the center. Now as you go deeper with the progressive cuts the hole appears in the piece that will be removed. Number 2 is better.
See the photo with the Aluminum plate on the CNC Machine and you see the 0,0 hole
Yeah, you would have to actually diddle with Carbide Create to generate the G Code OR using copilot it will generate the actual G Code program for you
Using the Carbide Create free 2D software program provide a G Code listing to cut a circular area using inches, in aluminum, centered at 0,0 and 3 inches in diameter to a depth of 0.03125 inches.
Here is a clean, ready‑to‑run inch‑mode G‑code program that will pocket a 3.000" diameter circle, centered at X0 Y0, to a depth of 0.03125" in aluminum using a simple spiral pocket. It is compatible with Carbide Motion / Carbide Create–style GRBL controllers.
G‑Code for 3" Diameter Pocket (Depth 0.03125")
gcode
(3.0" DIAMETER POCKET, CENTER 0,0, DEPTH 0.03125")
(ASSUMES Z0 IS TOP OF STOCK)
G20 (Inches)
G17 (XY plane)
G90 (Absolute positioning)
G0 Z0.200 (Safe height)
(--- Move to start point on circle ---)
G0 X1.500 Y0.000
(--- Plunge to cutting depth ---)
G1 Z-0.03125 F5.0
(--- Spiral pocket: 3 passes inward ---)
G3 X1.500 Y0.000 I-1.500 J0.000 F20.0 (Outer circle, 3.000" dia)
G3 X1.000 Y0.000 I-1.000 J0.000 (2.000" dia)
G3 X0.500 Y0.000 I-0.500 J0.000 (1.000" dia)
(--- Final cleanup circle ---)
G3 X1.500 Y0.000 I-1.500 J0.000
(--- Retract ---)
G0 Z0.200
G0 X0 Y0
M30
How this program works
🌀 Toolpath structure
G20 sets inch mode.
G3 arcs cut counter‑clockwise circles centered at 0,0 using I/J offsets.
The tool starts at radius 1.5" (diameter 3"), then spirals inward to clean the pocket.
📏 Dimensions
Pocket diameter: 3.000"
Center: X0 Y0
Depth: 0.03125" (1/32")
Safe Z: +0.200"
⚙️ Feeds
Plunge feed: F5.0
Cutting feed: F20.0 (Adjust for your tool, machine rigidity, and coolant.)
What you actually do now is to copy the G Code and place it in a NOTEPAD blank template and save it as a text file with the name SpkrCOut (shorthand for speaker cut out). This saved text file is then placed into the G Code file of the cutting software (I use Mach III) and you are good to go.
The Aluminum plate is 1/16 inch thick and for a tabletop machine that can be a bit of a struggle. So, I set the cut depth for 1/32 inch and with the center cut point at 0,0 (the circle center) you make the clean cut in 2 passes.
In summary the use of the AI software can generate the G Code for you and a definition of what is happening. Noteworthy is that Carbide Create does not give you the detailed "what's happening" explanation such as shown with copilot.
Check this link for more info on CNC Machining (pre-AI) from N6QW.
We now have to address that awful fact that you want the performance of the Xiegu 6200 but want it at a CW Pixie price ($23). Friend there ain't no free lunches so get a good CNC Machine and here is one that can be had for around $500 but will actually cut metal.
Now the skills you learn with a CNC puts you right in line with those needed for a 3D printer. This is a steppingstone!
In a subsequent posting I will take any who are still reading the blog through a process of taking a schematic and converting it to G Code for cutting a PC Board
There are them that know and those who wished they knew. Many in this latter group voted for old what is his name!
73's
Pete N6QW
