For this project I am trying to use KiCAD in the most unsophisticated way and still need help… First some background.
For a restoration project, I want to reproduce the ancient, single layer crossover filter boards of my 1970s speakers. Very low-tech analog stuff. I’m not sending Gerbers to China as I would for a normal project. Instead, an acquaintance who owns CNC equipment will mill the single layer, copper clad FR4 boards that I recently bought. So, I need a DXF file.
I could have used any 2D vector based design software to make them. However, I decided to use KiCAD for ease of reproducing the layout and placing components while drawing the copper zones. Will try my luck converting the Gerber output of KiCAD to DXF.
For now I’m drawing the copper zones and placing the drill holes. In the original boards, the holes for the component leads (non-plated through) are drilled into the copper zones. When I try to reproduce this in KiCad, I choose NPTH, mechanical ‘pads’ of the components to try to make these holes. Same for standalone drill holes (for a wire, not a component).
KiCad gives these holes a clearance to the copper of the zone in which the hole is placed. In the PCB layout editor it looks like this:
Is there a way to instruct KiCad to remove that clearance so that the copper runs right up to the edge of the drill hole? The board will probably be perfectly usable like this. However, it would be nice to get rid of the clearance.
The best way is to treat is as any normal electronics project, and draw the schematic first, then assign footprints and draw the PCB. This gives you real pads, with or without thermal reliefs (your choice), and a bunch of other advantages, such as nice straight lines with a low poly count, easily modifiable PCB (Capacitors have gotten a lot smaller in the last 30 years, the capacitors you used then may be obsolete now)
There is no need. KiCad has direct DXF output. There are also programs like coppercam (commercial and apparently works) and Flatcam (Open source, but in need of serious maintenance) that can directly read Gerbers and output G-code.
For the rest, you are probably using NPTH and then the “Copper to Edge” clearance will be used. For DIY, you can also simply use small holes in KiCad (for example 0.001mm) and then drill them bigger.
Thanks for the suggestion. Of course I did all this, exactly as the workflow should be.
Excellent. Where can I find it? I looked under “Fabrication outputs” and “Export” but didn’t see anything that looks like DXF but this could be my ignorance. I’d much appreciate some further guidance.
This sounds quite relevant to my quest. Could you please elaborate? Yes, I am using NPTH. And yes, there is a small clearance. Do you mean that KiCad always inserts some “Copper to Edge” clearance when using NPTHs?
I am encountering some discrepancies in my endeavor to accept this statement.
The reason I suggested this is because without a schematic and the netlist this creates, the PCB editor is not aware of clearances. If you don’t want to go through the schematic creation and footprint creation and assignment, an alternative is to use a bunch of free standing test points, and then assign THT pads to these test points. This way you can put them wherever you like, and if you put them in the schematic, you can also easily label them in groups.
Why, I don’t know, but none of the nets I defined in the Schematic editor showed up in the PCB editor. My best guess is that because I am using NPTHs for all holes in the board (also for the leads of THT components), there are no electrically connected components and hence no netlist.
It is still helpful to have assigned (and created) the footprints I needed, because without that it’s no easy task to determine the drill hole locations.
Sure, I’m misusing the software a fair bit here. But it seems to work.
Without showing the rest of your project, we are looking though a very thin straw at what you are doing, but I’m almost certain that going to a normal KiCad project is easier, but that is assuming you know how KiCad works. And indeed, NPTH can not be used for electrical connections. KiCad needs to see copper for that.
Project. And only ever opening the schematic and layout editors out of the project. I have been through not doing that long ago.
I really think it’s the NPTHs causing the absence of electrical connections. I may try PTHs without annular rings to see if that fixes the netlist.
But it doesn’t really matter. I really just wanted to remove the clearance between copper and hole’s edge. That’s done now and it looks just like the original.
The schematic and board are so simple that I don’t need most of KiCad’s functionality. I am simply reproducing the existing layout of the boards with minor changes to component placement, trying to make faithful reproductions of the original 1970s work. I put the board on a flatbed scanner and loaded the image in PCB editor as a reference. Then I drew the weirdly-shaped zones manually.
For this I could easily have used Adobe Illustrator or Inkscape. However, I wanted to use KiCad to be able to place and move around the components easily to make sure all holes land in the correct zones.
Which reminds me. Drawing irregularly shaped zones by placing many ‘corners’ on rounded lines (i) is a pain, and (ii) never looks very smooth without time-consuming tweaking of the corners, trying to get smooth curves. I tried creating zones by making line segments with the arc and line tools, with mixed success to I ended up just drawing using the zone tool.
As feature requests go, I am aware that this particular use of KiCad will likely, and understandably, have very little (if any) support in KiCad’s user community. But here goes: adding pen and curvature tool functionality à la Illustrator to KiCad for zones and other shapes would be great for this purpose.
Looks like I’ll be CNC-ing my first PCBs soon. Fun stuff.
