----- Original Message ----- > From: Lorenzo Marcantonio <[email protected]> > To: Kicad Developers <[email protected]> > Cc: > Sent: Thursday, December 5, 2013 10:10 AM > Subject: Re: [Kicad-developers] Development of IDFv3 export > > On Wed, Dec 04, 2013 at 12:28:55PM -0800, Cirilo Bernardo wrote: >> That's a good idea. If we could extrude a courtyard rather than the > silkscreen outline then we would meet all the functional mechanical > requirements > of IDF3 by simply adding a height to each component. Extruding an outline of > the > silkscreen won't quite work though since in many cases it won't serve > the purpose of the mechanical fit check. On the other hand, maintaining > component outline files in the manner that we maintain VRML files would be a > royal pain in the ass - so much so that, in the absence of courtyard > outlines, I > am tempted to simply extrude the silkscreen outlines simply to provide some > sort > of markers and give the users a general idea of the component locations. I > see > the IDF exchange with MCAD as good enough for many purposes, but things will > be > much better when/if I get around to doing proper 3D modeling. > > How other people do it (e.g. Altium, IIRC), extended by my own ideas: > provide layers for explicit mechanical extrusion, when it's missing extrude > the assembly layer, when everything else fails do the courtyard. And the > specified model obviously wins if it's specified. The extrusion layer > would be used for non rectangular things (like aluminum caps or simple > polygonal items like THT power resistors), assembly for most rectangular > things, and obviously a model for critical stuff like connectors, > switches and buttons. > > Rationale: the courtyard contains the pads and the fabrication excess so > it's way too big. The assembly box (usually folder-thing shaped) is in > maximum material condition so it would be a really good candidate (*if* > it's only an outline... for example I put an arrow there to indicate > the insertion side for connectors; that would break it). > However it's always a box so an intermediate shape would be useful > (instead of a full model): that would be the mechanical extrusion layer > (maybe height could be encoded there as width, like in eagle? it's ugly, > I know). The silk screen is absolutely not-useful since it's usually not > even a closed shape (example: the inspection bar/dots). In fact some > silk conventions *break open* the shape to indicate pin 1! > > To make things simpler: just use the specific layer and put a function > in the module editor to copy the assembly or whatever and create > a default extrusion (with specified height); the user would then edit it > if needed. Then during exports just process that layer and ignore the > other stuff. >
Thanks for your comments. The more I think about it, the more I suspect that the least intrusive compliant IDF solution is to maintain IDF footprint files in a manner similar to what we do with VRML. I'm not really keen on that though since I see IDF as being of rather limited use. I'll post on the user's list and see if I can get some comments from habitual IDF users. For my own use I like the ability to generate my board solid model with holes in it and I'm quite happy to spend a few minutes manually putting in models of the more critical components; even in a previous project with over 400 components on the board there were fewer than 20 components which required good models. >> Ultimately the MCAD doesn't care about the holes; with SolidWorks I > simply have a cut outline named "PTH" which contains the location and > size of all PTH and the same goes for NPTH. Even the mounting holes which > happen > to be plated go into PTH, so I can't even distinguish mounting holes from > others based on the name or grouping within SolidWorks. > > It seems that's a 'nobody care' value, then:D (still hoping for a > flag > to denote important holes, for filtering plots too!). > Well, it's an enforced "nobody cares" value since even an expensive MCAD package will not give you what you want even when IDF provides it. I wonder if CATIA does any better. What kind of flags would you put on holes and how would you use those flags? I'm just curious - not volunteering to code such a thing of course. :P - Cirilo _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
