FlatCAM pratical tutorial: copper traces geometry – Part 2
Now we have a base project to start work. First step is to create a series of geometries that become the passes used by CNC to isolate the copper traces.
For all the milling working I use this type of bits
You find here
I prefer the 30° version because It’s more durable, and works like a charm.
Now I must say that most of the operation are the result of experience, so you must know that this operations aren’t the better operations, but they are my better solution for milling PCB.
Generate trace isolation geometry
Now we are going to select with double click the Gerber
PCB_PCF8574_03_copperBottom.gbl where we can find the information about the traces.
Now you have the Isolation routing panel, here you have 3 parameter:
- Tool dia (black): the diameter of the tool you are going to use
- # Passes (blue): the number of isolation passes you want (more passes more isolation of the trace)
- Pass overlap (red): the percentage of Tool dia to overlap between the pass
Now here I’d like to do a consideration, my idea is that we prefer more possible copper area, because if there are some problem or autolevel is not properly setted we don’t put out the work.
So I’d like to extend tool dia as much as possible, and you check this parameter directly on the draw of the Geometry generated, search for the closest items anche check if the geometry is broken.
Here an example with a tool size of 0.57
So I’m going to reduce the tool dia since 0.55 and the size permit to the geometry to have the correct size
This is a perfect solution for me, the result is a clean board with a good quantity of copper, and you have better result if you want more thin copper trace, but if you need more space from trace to trace (like for smd) you must try more fitted Tool dia.
As you can see I do 3 passes, you can understund the mean of
# Passes in the draw, this value is combined with
Pass overlap that set how much overlap, for example with 50% overlap you have:
Or if you insert a 33% overlap
The idea is to remove more copper as possible, so bigger Pass overlap is better, but you must pay attention, first we are using a bigger Tool dia, and 50% probably cover only 20% of material.
If you use a too big overlap the result is this
Here a correct pass overlap
As you can see there is a check
Combine this is quite usefully, if you check It instead to create one file for pass
It generate only one file with all 3 geometry
I prefer to create 3 or 4 file and group only first 2.
To group 2 or more geometry you must select they with
Shift + mouse click or
Ctrl + mouse click than go to
Edit --> Conversion --> Join Geo/Gerber/Exc --> Geo, as result you obtain a new file with the join of the geometry you select.
I group only 2 geometry because I create a first gcode for this, I send the work to my CNC than If the isolation seems sufficient I don’t do more, if It isn’t sufficient I generate an additional gcode only for the third isolation geometry and so on with normally the limit of 5.
Here an example of single pass
beautiful, but very difficult to solder and quite dangerous, humidity or dust can create a short circuit.
Result of first 2 passes
Don’t worry, the PCB isn’t clean, at the end when you clean It you got a good surprise.
The same but clean with sandpaper
Result last pass
- FlatCAM pratical tutorial: introduction, installation and import
- FlatCAM pratical tutorial: copper traces geometry
- FlatCAM pratical tutorial: clean non copper area
- FlatCAM pratical tutorial: silkscreen geometry
- FlatCAM pratical tutorial: contour
- FlatCAM pratical tutorial: gcode and PCB milling
You can find Gerber, fritzing, images and FlatCAM project files here.