← Back to team overview

kicad-developers team mailing list archive

Re: About MCAD integration


----- Original Message -----
> From: Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>
> To: Kicad Developers <kicad-developers@xxxxxxxxxxxxxxxxxxx>
> Cc: 
> Sent: Monday, May 6, 2013 4:31 PM
> Subject: Re: [Kicad-developers] About MCAD integration
> On Sun, May 05, 2013 at 06:50:50PM -0700, Cirilo Bernardo wrote:
>>  checking information such as panel cutouts for PCB mounted parts. In
>>  practice I've taken IDF3 files and replaced critical components with
>>  adequate 3D MCAD models; this isn't so bad in many (most?) cases, but
>>  I believe we can improve that. :)
> *If* you can import IDF3 usually the important stuff (connector,
> switches, display, that kind of thing) can be inserted aligning on a pin
> hole. I do this with DXF :D
> BTW can DXF with heights be imported in MCADs? that would be a really
> quick way (and would give 99% of the informations found in the IDF3).

In SolidWorks I can import a DXF and extrude, but IDF3 would still be preferable due to its wide use. I'm also not sure if SolidWorks will directly import an extruded DXF. Anyway, DXF in SolidWorks drives me insane and makes me scream.  If we will only be doing extruded footprints I would recommend implementing an IDF3 exporter. Some people also work the other way, mainly with the MCAD generating a board outline and mechanical keep out volumes, but in my limited experience I believe the exporter would be much more useful; putting the keepouts and board shape (at least in my projects) is easily done by checking the mechanical drawings.

>>  someone has to put in the time to create the footprints and manage
>>  them.  This is a big job and it is why I haven't put any effort into
>>  IDF3 export.
> IDF3 is using prismatic approximations, so it wouldn't be a big burden
> to maintain. For most things you simply give an height to the silk
> outline, like eagle people do (I hope to see some kind a layer when we
> get to them).
>>  people seem to use PSI5 (like STEP, you pay $$$ for the
> Never heard of it... maybe an american standard little used in europe?

It's one of those standards maintained by an industry committee - I believe it's managed by the Germans. Yes, you don't hear much about it despite its use in some industries.

>>  Don't even think about implementing a STEP library; that's a job 
> which
>>  would take a large team many years. It is best for us to make use of
> *If* the target is only exporting the board outline with holes and maybe
> the component extrusion (the equivalent of IDF3), it can be feasible
> even in house. In the boundary representation mode for 'simple' thing
> by face/edge/vertex it's no more difficult than, say, a 3ds file.
> I tried adding a hole and it only added an edge (from a cylindrical
> surface, directly from origin/radius/length!). However anything more
> would be a *huge* work.
>>  existing tools like OpenCascade, but I also suggest that MCAD support
>>  should be done by external tools and we should not make KiCAD
>>  dependent on any specific MCAD.  A scheme I suggested last year should
>>  work OK and require minimal support in KiCAD - basically a few more
>>  tags to point to 3D models, which is similar to what is currently done
>>  for VRML.  The 3D model associations will have to be abstracted so
>>  that KiCAD can manage the associations without really caring about the
>>  specifics of the 3D tool (MCAD, VRML, etc).
> Technically the board could be generated from the outline gerber and the
> pick and place file (it works that way in *real life*:D)

I think that using the Gerber files and pick/place would be great.  We only need the board outline, through holes, the component locations and some system to look up the IDF3 files.

>>  Ultimately STEP is probably the most supported format for exchanging
>>  3D information; however it is an inconvenient format to use within an
>>  MCAD due to the memory consumption.  My idea was to wait until FreeCAD
> I don't think anybody would use this internally. The 'E' in STEP 
> stands for Exchange...

No one manages their own models in STEP format, but it is not unusual to include many models from other parties.  For simple models I let SolidWorks attempt to duplicate the model in native format.

>>  3D effort can also be concentrated on native FreeCAD descriptions and
> Let's be real... nobody in real life uses freecad in production... we
> need something that could be eaten by solidworks/inventor or at least
> autocad.

For me FreeCAD is only a means of generating STEP which is available to everyone, and for hobbyists perhaps a way to do their own mechanical design without paying huge amounts of money for the software. Who knows - maybe people will start to use it for production work as it improves. I can write a tool to export a board to SolidWorks, but no one will be able to use it except for people who have a license; in addition to that someone else will need to write such a tool for Catia, ParaSolid and whatever else is out there.  STEP is really the best option if you want greater operability with MCAD. I think in the short term it would be more important to support IDF3 and in the long term STEP. As far as I can guess, I think IDF3 will be part of many people's work flow for a long time yet; however, if you design a PCB with many buttons, lights, and jacks and you want someone else to design a case, it's easiest if they are supplied with a STEP model.