Mechanical alignment in Pcbnew


#1

Designing a PCB with accurate mechanical position of components is critical to aligning with mount holes, front panels & heatsinks etc…

Using CorelDrawX4 as my mechCAD, it has guidelines to assist placing graphic objects accurately,
The method below of using “guidelines” in Pcbnew . You cant snap specifically to the guidelines (maybe in a future version) but placing vias & components is visually simple & accurate.

Mechanical CAD import in Kicad:
Kicad imports older DXF version & this has so many segments in a straight line & curve it is pain to modify.
I have tried deleting segments to make a single line but its too time consuming.
Sometimes a change in dimension will occur before final or later PCB revision, & all those little segments, grrr…
Hopefully in near future Pcbnew will import other format like Postscript (it exports this) or Metafile in later version.

If you have a board with 2 axis symmetry, choose 0.0 origin as the board center or otherwise a board edge or whatever.

Method: (this is just an example using default sheet size)
Start by selecting coarse grid like 1.0mm
About center of worksheet, with cursor on say 150.0 x 90.0 press space-bar, this sets relative coordinates = 0.0
Select a layer like Dwgs.User, using tool ‘GraphicLines’ hold key & draw X & Y “guidelines” starting with your 0.0
Using your mech drawing as reference, draw thin (0.05mm) X & Y lines for the other components & mounting/heatsink holes.
Zoom in & pan to check all is on grid where supposed to be, you can also check the line properties.
You now have a set of guidelines to position components accurately. It is easy to see alignments.
Be sure to turnoff this layer so don’t accidentally move a guide while layout PCB. (Kicad currently does not have locking for these lines)
refer attached files for reference.

Pcbnew will have in a future release a 0,0 grid origin that will reflect in the edit properties, i am eagerly awaiting…

Mech example-1.pdf (55.7 KB)
PCB Mech sample.kicad_pcb (52.3 KB)


Transforming a schema into a pcb
#2

You may have a look at

This may help for creating the pcb edge accordingly to your mechanical design.


#3

This thread could also give some ideas: How can I place my pad exactly where I need it?

For example, it looks like you could have the user grid 15x5 and position leds and switches almost directly. Align and Distribute tools would work well, too.

I agree about guidelines, I miss them too.