Off Topic Hobbies > Mechanical Engineering

Origin and Axes in CAD

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gnuarm:
I recently found out that KiCAD defaults to to the origin being in the upper left corner of the drawing and positive being down.  I'm told that in mechanical design the origin is typically in the lower left corner and positive is up.  Is that true?  If working on the mechanical aspects of a design how much does it matter that information on the PCB is oriented differently. 

Has anyone had a problem communicating information between EDA tools and CAD tools because of this?

fourfathom:
I've been able to work around the KiCad origin issue with little or no problem, but it is a detail that can be annoying.

But the new KiCad v6 release will apparently fix this, putting the origin at bottom-left, and the + directions up and to the right.  Here's a thread on v6: https://www.eevblog.com/forum/kicad/kicad-6-is-coming!/

gnuarm:
Yes, thanks.  I am aware that the problem has been resolved in KiCAD and now you only need to change from the default.  i was just wondering how much of an issue it was in the first place. 

For me it would involve remapping everything when working with the software since the mechanical guy would be working in one orientation and my layout software would be working in another.  I don't know what issues might result when using CAD generated data.  The project I am currently on uses KiCAD (not the new release with the axis fix) and the mechanical design exchanges 3D data with KiCAD.  I suppose that is via a standard and automatically converts the axes. 

JohnnyMalaria:
Presumably, it creates the Gerber files with the standard axis orientation otherwise PCBs would come back mirrored. It doesn't seem to be an real issue. FWIW, Windows GDI has the origin at top-left which maybe is why KiCAD evolved that way.

gnuarm:
Not really talking about the Gerber files.  Every board needs to be mounted and often they have connectors which have to line up with the openings in cases.  I've even seen connectors that are fastened to the case as well as the PCB.  In those cases there has to be a common framework for communications. 

That's what I'm asking about.  Do people have problems when the PCB layout tool uses a different frame of reference, or is that already worked out? 

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