Working with Data from Multiple CAD Systems

Instead of translation of just the geometry (when it does work with compatibility between different cad platforms, it would be great if the constraints also would translate.

I think that the developers will keep guarding their secrets for quite a while. Once you get cross platform formats it will open the door to open source (i.e free) CAD programmes just like you have in word processing. This will hit the developers revenue.

Autodesk guarded the DWG format way too long.

There already are open source CAD programmes. One is Salome:

https://en.wikipedia.org/wiki/Salome_(software)

https://www.google.com/search?q=salome+cad&biw=1433&bih=778&tbm=isch&tbo=u&source=univ&sa=X&sqi=2&ved=0ahUKEwiV6P71tqLLAhXGKyYKHZojD7QQsAQIOQ&dpr=1

You're right, there are a few programmes around but none that can read everyone else's files.

But do all the different platforms USE constraints?

no, but I would have to agree, if they could quite a feat to have them transfer.....

Like I mentioned earlier, it seems its just geometry the transfers.

Now, for standardizing file formats, no the contracts don't have to transfer. but for collaboration between custom suppliers it would be nice.

As far as standardizing,.... they has been going on since the first (2) CAD programs came to market.

But considering what one had to go through in the 80's-90's I shouldn't complain, hell, back then, I was happy if the geometry did import, without having to go into the DXF file and edit the problem out.

IN CONCLUSION....

You touch on a lot of problems that most don't realize... how is the geometry created.

And that depends on the final usage that drives it. With an example is stereolithography printing uses skin triangulation

It also comes down to a number of environmental constraints,.... processing time is one I can think of off hand.

When it comes to different applications, say a 3D image render that wants single-sided triangular facets, and a Fused Deposition Manufacturing machine, which wants horizontal slices rendered into 'tool path splines,' we need a 'base format,' that will define the shapes in a common format, which the 3D render engine will translate into facets and the 3D printer software will translate into splines layers. I'm not sure what sort of base format that would be, whether defining a curve, axis & rotation/transition, or defining a primitive solid and stretch/squash distortion, but we NEED a 'common language' to branch off of. Just as PLC's gravitated towards Ladder Logic diagrams as their 'common tongue,' even if the PLC itself was programmed in Assembly. The Ladder Logic provided the 'common tongue' needed for people to see WHAT the PLC was doing, and use that knowledge to program a new PLC when the old one was obsolete and discontinued.

Someone elsewhere on the thread mentioned that Open Format Standards hurt developer revenue because people can choose to migrate to a cheaper platform. That is called 'open and fair competition' in the marketplace. Preventing that is known as 'Vendor Lock-In,' and while it is good for short-term developer profits, it hurts the users, and hampers true innovation.

we need a 'base format,'

That's right.... that would be a lot simpler to adopt my CADD platforms, and then from this base format to be exported export to the required end process format.

I recall about 15-20 years ago, they actually had a term for this format. And they (think tank or industry????) were really trying to push for this but intent was great but it was extremely hard to get everyone on board or agree on the final format.

Because it completely leveled the playing field because everyone had to start from scratch.

I can't imagine any workable CAD package not including constraints. There's really no way around it.

I'm not quite sure what you mean by constraints. The constraints I'm used to are usually holding down the shift key, which makes objects move only Horizontally, vertically, or at certain preset angles. Another is it will make the line tool only draw lines at those preset angles, or the rectangle tool only draw perfect squares.

But this kind of constraint only has to do with the process of drawing, and has nothing to do with the files used to store and transfer the finished drawing.

Are there constraints stored with the data of the drawing?

In inventor;

Constraints are applying, length (or size for circles and radius), angle, positioning to (inline, perpendicular, tangent, etc.....) in the sketch geometry.

And in the modeling assembly's on how its located with the other models, such as tangent to, distance from (Center or surface) , alignments (such as holes), etc....

it basically comes down to geometry driven as oppose to dimensionally driven of which I believe where your referencing.

And yes, these constraints are stored in the file itself.

To go farther, these constraints are given an identifier name such as d1, d2, d3, etc.... as a default.

so you dimension a line at 2.25"

inventor assigns the variable of d1 = 2.25"

the second geometry is a radius of 3.125" Inventor assigns the variable name d2 with a value of 3.125. and so on.

You can not if you need to give variable names more descriptive so you'll under stand

These identifiers are actually variables that you can access and change the to a more descriptive such as;

d1 = base line

hence

base line = 2.25"

you don't have to , but you can look at it as parameter programming and that its good practice.... if you doing similar parts that use similar models.

Then your project can apply other geometry that is depended upon these variables such as d12 is always 1/2 the size of say d4

so d4 value is 5.75" d 12 value would have a value of a formula of "d4/2" and also can be basically can be driven off a spreadsheet,

I have seen turbine design run this way.... but it was off of Solidworks. which is slightly different but the same general concept.

Just to add to that, an Inventor assembly file does not contain information about all of the sub-parts. It is basically a list of all of the parts that make up the assembly & a list of how those parts relate to each other.

...And the thigh bone is connected to the hip bone, the knee bone connected to the thigh bone, the leg bone connected to the knee bone, and the ankle bone connected to the leg bone....now hear the Word of the Lord.

yes,.... I kinda got carried away.... the reason for a list is streamlined files size by eliminating redundancies.

Thanks. I've been using Vectorworks software (and its predecessor MiniCad) on Macs for very close to 30 years, so obviously I'm quite accustomed to it, although I've only learned to do 3D in the last couple of years. I've used it mostly to design electronic circuits and robotic machines. Unfortunately for me, recent development in the platform has been directed at landscape, architecture, lighting, and BIM, none of which are important to me.

I gather that those things you are referring to as constraints stored in the file are essentially what I've considered properties of the objects. On the other hand, this program only costs roughly $2k +$500/year per seat, so there are clearly capabilities that more expensive systems must have that mine doesn't. It is obvious to me that the 3D platform is not nearly as fully developed as the 2D platform.

Still, the fact that I can import an IGES file created in, say Catia or Solidworks, and that those programs can import IGES files I've exported, shows that a common file format could be developed, either using IGES as a starting point, or starting from scratch.

I have designed solid parts in Vectorworks, exported the files as IGES, sent them to our machine programmer, who uses Mastercam (I think) to create the CNC file, and gotten the finished parts the same day. The parts have always been precisely what I intended.

I assume that none of those open source CAD programs run on a Mac. If there is one or more that does, I'd be more willing to learn a new CAD system than I would be willing to switch to a PC.

I've had pretty good luck sharing files between systems using DWG/DXF for 2D, and IGES for 3D, but that means each CAD program must export to and import from those formats. It sure would be great if all the CAD companies could get together and agree on a single standard format...

Kudos to DKWarner once again! As usual, spot on comments. The electrical industry would never have reached the level of sophistication it has now reached (nor would electronics) without having conventions, organizations, and committees that meet and agree on industry standards. Design needs to advance to even beyond this level, and produce a working standard that will be transportable across a range of platforms, and that meets a variety of user needs including affordability. Sole entrepreneurs might not be able to afford the most sophisticated CAD software, and when they switch to "cheaper" code, they end up with something imported that does not want to shake hands well with "how we do things around here". Just my uninformed opinion, not necessarily fact.

Maybe there could even be different levels of the "new" standard, that would support the work of very small engineering firms (1-2 people) up to someone like Boeing, or Raytheon. That way, the largest firms could send work to the smallest contractors and back up the ladder. I think this was done already in the Apollo NASA program, but I am not sure. All I do know is that during the design and production of the Saturn V launch vehicle, there were something like 1,000,000 parts to keep track of (all with their specifications), and as many as 20,000 individual contractors working on the program. How the hell did NASA keep up with all this? Not even the greatest genius could keep track of all this without a proven system.

I heard about a story where Werner Von Braun was being confronted by management about he and his group of German engineers receiving modules, rockets, etc., and taking them apart for inspection. The "boss" was saying: 'You guys are slowing us down tremendously by not trusting the contractors'. Werner retorted by pulling a rag of his pocket and stating: "See this rag, this is what we found in the rocket delivered by your contractor. Your people are not operating up to the standards we require." End of story. Now you know why no Saturn V ever blew up on the launch pad or during launch. I suspect that if NASA had paid the same exquisite attention to details during the Space Shuttle program, there would not have been the same levels of failure, although NASA was asking a lot of that program, and overall had a "decent" level of safety (in spite of their total negligence of things like cold weather effects of elasticity of O-rings, etc.) in a very risk intensive field of endeavor.

Risk is a relative term, and is different from one field to another. Safety has several common denominators in high risk fields, as to how things are planned, how things are done, and how things are inspected. It has to be this way, not because contractors are negligent creatures, but because we are all mere humans, and human error always takes place. It is not so much that we make mistakes, what is important is when do we catch the mistakes, and what do we do about them. Missions of high importance must be done right the first time, because you do not get a "do-over". It is like learning to play the piano - at first, you will falter, and you will start over and over and over, but soon you learn to "walk with the keys", then run. Just remember that while running, do not hold scissors and expect not to get hurt.

CAD suppliers have been moving towards this. I use Inventor & looking at the 'open file' dialogue box I can see that, apart from the usual exchange files like STEP, IGES & Parasolid, I can directly open CATIA, Pro/Engineer, Rhino & Solidworks files. I'm sure other CAD suppliers must be doing the same.

Does anybody know how to open a Solidworks SLDDRW file in AutoCAD? AutoCAD will let me import other SW formats (.prt, .sldprt, .asm & .sldasm) but no luck with .slddrw.

You have to 'Import' instead of 'Opening'. Start a new blank drawing, type IMPORT hit return then select the Solidworks file type from the drop down list.

I've tried that but the .slddrw file is not on the Solidworks file type options, it's the only file type I've come across (so far) that I can't Import!

You're right, I'd never noticed that before.

Yeah, I only noticed it when I needed it :-), seems strange when you can Import other files.

I don't know AutoCad, but other packages I've had had a separate executable for 3D drawing and 2D drawing. Is it possible that the .slddrw file is 2D and needs to be imported from the 2D drawing programme?

Unfortunately not, although we work predominately in 3D, our software includes the 2D programme & the input filters are the same for both.

Oh well, it was at least worth a try.

Good point, and this is precisely what this thread is about.

Heck where I work, not everyone has access to any drafting program at all, much less something that is platform wide in acceptance.

I still have to draw sketches with Excel, and hope to God maintenance can figure out what I mean from all the pointing and grunting. Usually, I just chunk rocks at them, and wave my club around until they get the idea, and pour the concrete here, dig over there, and install a beam pointing up, and an electrical box pointed that way. Good thing I chose to be a chemist, or I really would be in trouble. LOL I come from a long line of farmers whose surnames indicate something about being a lumberjack.

I work with AutoCAD ASD, so to let one of my clients see my work I have to Export my ASD to a Standard DWG, open exported file in standard AutoCAD, then convert to SAT File, end up with 3 different files all with same info, just different formats,

Sounds like your team would excel at a certain board game:

https://www.fantasyflightgames.com/en/news/2012/9/6/ugg-tect-is-now-available/

Mental age range of that game please? If it is over 10, I don't think it will fly here.

Even with the same software you encounter problems, when someone has paid lots of £$€ for a standalone license but is not willing to pay even more for the current version.

True, these are not backwards compatible.

Right! I could find no improvements of use to me in my current upgrade, so I skipped it. I know I'll have to upgrade in a year or two, or eventually be pushed out completely.