I want to create a square-shaped hole in a PCB to accommodate some mechanical parts. Normally, when creating circular holes, I define them using “1pin” from the “connect” library, and select a circular drill. However, there is no option to define a square-shaped hole this way (not that surprisingly…)
Is it all possible to define a square-shaped area to be cut out from the PCB in KiCad? If not, I should be able to work around it by creating a circular hole and having a square hole cut out after the PCB has been fabricated.
It seems like I can define a square cut out by drawing it on the EdgeCuts layer (same layer that defines the edge of the PCB). The fab house I normally use, OSH park say:
Cutouts aren’t officially supported, but the fab has been doing them pretty regularly as long as they’re drawn on the board outline layer, and are at least 100 mils wide.
To try making a cutout, draw the outline of the cutout on the board outline layer, or draw the path you’d like the milling tool to make using a 0.1" wide line. Cutouts won’t be plated.*
Cutouts are always made by milling, so you cannot really obtain true squares but squares with rounded corners at best. Depending on the size of your square, it may be easier (and cheaper for the fab) to make oversized round hole than mill the square with tiny router bits…
Here’s a generic approach to approximating a rectangular hole for mounting slots. I use it for certain types of audio connectors that have wide mounting clips for strain relief:
Note that the DFM checks by most fab houses will count this as a “slot” or “cutout”, just like with the edges_pcb layer approach you mentioned, and will either not allow it, or bump your order into a higher “service quality” bracket and charge you more for it.