A few days ago I successfully carved a circuit board with the Be a Maker's Shapeoko 2. Below you will find a short write up on how to do basic milling operations as well as running a entry level CNC machine with a program called Grbl Controller. At the time of writing this guide, Grbl Controller and MakerCam are both free to use.
Both of these programs take a lot of the hassle out of complicated CAM software and make it a perfect choice for anyone with an interest in CNC controlled machines.
To begin go to File > Open SVG File.
I typically will draw all my parts in Adobe Illustrator as the drawing tools in MakeCam are not that precise or intuitive.
Now that your file is loaded into MakerCam, you have to decide what you would like to do with it. MakerCam gives you the options to cut the profile of your geometry, to drill through, to hollow out, and a few other basic milling operations. For this instance we will only need to do one operation, a profile operation.
Go to CAM > Profile Operation.
A profile operation follows either the inside or outside of your drawn geometry.
A small pop-up window will appear giving generic feed rates, step down, and tool parameters. You will insert your unique parameters in these fields. For cutting a circuit board I found that these settings work very well.
Tool Diameter: 0.03 in
Target Depth: -0.01in
Inside/Outside: Outside
Safety Height: 0.25 in
Step Down: 0.01 in
Feedrate(In/minute): 10 in/min
Plunge Rate(In/minute): 10 in/min
Go ahead and click Ok.
Go to CAM > Calculate all.
This will calculate any toolpaths that you have defined. In this instance I only used a profile path, but you could create a drilling operation to center drill all your holes. In this instance though, by selecting all the lines with a profile path, I knew inevitably it would go back and do inner profiles of all the holes leaving marks for me to drill later.
Once you have calculated all the geometry, you are ready to go back to:
CAM > export gcode.
This will open up a dialog box which will allow you to select any or all tool paths you would like to export.
The next thing we have to do is load our newly formed (.nc) file into a program that can tell the Shapeoko what to do and where to move. For this at the museum we use a program called Grbl Controller. Sadly I did not get any screenshots of the program, but the interface looks something like this:
In this application we can load our previously created part file, jog the position of the spindle, turn the spindle on/off, and a whole slew of other features. The most important steps before I began cutting the circuit board was zeroing the machine.
To do this, use the arrow buttons on the program to move the spindle to the home position(x0.00, y0.00, z0.00). Be mindful of the units that your machine is set to. Our machine is set to inches, so when the step size says "10" that means 10" which will no doubt bottom out your spindle with the bed (you better flip the power strip ASAP, trust me I've done it before).
In most instances you will want to zero out your machine in the bottom left corner of your work piece, but refer to the part you created in MakerCam which will dictate where your home position will be.
Keep moving your bit lower till it is just above your work piece and you will be ready to begin the job. Throughout the job it is a good idea to remain close to the kill switch just incase all hell breaks lose, and a unit mismatch causes the machine to unexpectedly plunge.
In the first 5 minutes of a job you will be able to tell if everything is going alright. If you hear the machine stressing to cut through the material it is a good idea to slow down your feed rate or decrease your step down.
On this particular job everything seemed to be going very smoothly.
I believe these settings were perfect in this instance. The plunges were fast and accurate and the profile paths were fast, without ripping the copper.
As you can tell from my other projects, I really like to make a mess.
Thats all there is to it! This board has been continuity tested and we found that all the traces are isolated. If you look closely you might notice that some of the circles are slightly oblong.
Possible causes for this occurrence are that the x-axis or y-axis is losing steps, when I moved the bit across the surface I noticed I broke the tip of the bit meaning that when the bit plunged there could be some deflection off of the assigned path, or operator error.
That being said.
On behalf of the BAM space, we are incredibly pleased that this board was milled in about 30 min and is the first of many boards the Be a Maker space will prototype and produce for our exhibits!
If you have any questions, leave a comment or email me.
Comments
Post a Comment