Open source / Open Standard CAD development?

Mats Eriksson datorfixarn at
Sat Mar 8 01:52:03 CET 2008

First of all, thanks guys for interesting replies to my original post!

I really think by attracting more non-software to the OpenMoko project 
(and also to projects like OScar) could be the trigger for creating 
non-software developing communities. Many engineers are pretty tired of 
dealing with the messy CAx/"PxM" situation, and could probably sacrifice 
a high salary (like software developers started to do in the beginning 
of the 90's. It would probably take lots of resources (the resemblance 
with developing the Linux kernel is probably pretty accurate), but if 
just a small fraction of the amount spent on proprietary CAx/PxM systems 
could be spent on open source / open standard development, I think it 
could be possible!

Michael Shiloh wrote:
> I just returned from ETech, the emerging technology conference, and 
> some of us discussed this problem. (In fact, the conversation started 
> because of the Openmoko release of Freerunner CAD files.) All 
> programming languages have a common source code form: ascii text. In 
> contrast, there is no such standard for mechanical drawings or 
> schematic drawings.
What about STEP? It would be very good if CAD data could be human 
readable, and thus being able to use version control systems like 
Subversion and Git in a similar way to source code.
> Similarly, there is no single standard for image data. There are a 
> multitude: JPEG, TIFF, BMP, etc. but this is not as bad a problem 
> because tools exist to convert from almost any format to any other 
> format.
But the big difference between these image data and CAD data is that the 
specifications are open for the image data, but not for the CAD data. 
Please correct me if I am wrong.
> Since it's unlikely nor desirable that a single standard will emerge 
> for mechanical or schematic capture, we came up with the idea of 
> putting out a call to the open source community to develop tools to 
> convert from from one format to another.
> Some of this exists already, for example in Blender's ability to 
> import from a number of different file formats. But we would like to 
> see a project dedicated to creating a collection of tools to do this.
Could "CAx functionality" be built on top of Blender?
> Comments?
> Mark Arvidson wrote:
>>     The reason why I joined list is that I found the CAD files of the
>>     Neo1973 at the <> site. It is great
>>     that these files are
>>     available, even if they are in a proprietary data format (the 
>> ProE, not
>>     the STEP one), and very likely developed using a proprietary CAD
>>     application.
>> Developed with Pro/E if they are Pro/E files.
>>     Personally, I have a software development company, in which I have
>>     been developing tailored software for my clients, mostly with open
>>     source technologies, and sometimes with, at least well known, closed
>>     source techs like .NET . Therefore, it was a shockening moment 
>> when I
>>     during 2007 did a consultancy project for an industrial company
>>     producing water taps. It meant going back at least ten years in 
>> time,
>>     back into proprietary hell! Proprietary systems (including 
>> proprietary
>>     interfaces between systems) and proprietary data. CAD was done with
>>     proprietary software, often with more than one CAD system, 
>> resulting in
>>     incompatible, binary-only data.
>> Having come from inside that industry, I have to agree.  A very big 
>> mess.
>>     So my questions for the OpenMoko community are:
>>     * Does there exist any "usable" open source CAD systems? (Is perhaps
>>     Open CASCAE a viable semi-open option?)
>> Open CASCADE may be an option for a kernel.  I do not know much about 
>> it, except it has been used for numerical finite analysis more than 
>> modeling.  It could probably do the work, but perhaps a bit slowly?
>> CAD is a very complex subject.  There are many different solutions 
>> for mechanical design, but only 3-4 for parametric controlled 
>> modeling engines, and they are all high-dollar proprietary software 
>> packages with extremely rigid licenses.  To date, I know of no OSS 
>> projects to try to create a parametric modeling engine.  The original 
>> and on-going development of the 3D parametric modeling engines (such 
>> as ACIS or Parasolid) has taken many, many millions of dollars, so is 
>> a major OSS undertaking, perhaps similar to the Linux kernel.
>> Blender has a sort of add-on parametric plugin, but it is quite 
>> limited.  Alibre Design Xpress is free, but proprietary.
>>     * Is it possible to use a human readable format for CAD data? (Is
>>     perhaps STEP enough for development, or just a format for 
>> interchange
>>     between different CAD applications?)
>> STEP is a good, complete standard format that I believe all major 
>> packages support well.  If I were going to create an OSS 3D modeler 
>> with human readable format, STEP is a good way to go.
>> IGES is/can be a human readable format, but you lose the parametrics 
>> with IGES.  The format was design to drive CNC machines, so is more 
>> about the model exterior than anything else.  It's original design 
>> was based on punch-cards, so is very heard to read by humans directly.
>> There are xml formats, too, but none are really very standardized.
>>     And the most important question:
>>     * Is the OpenMoko community interested in  using open source tools
>>     (possibly together with a human readable format) for developing
>>     "non-software" parts?
>> I think this product has primarily attracted software engineering 
>> types.  We should get the word out to non-software people and 
>> increase the audience for that question.
>> --Mark Arvidson
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