Check for converting file formats

A customer asked me to verify the volumes on converted parts the other
day. Is that a reasonable way to check the accuracy of a conversion?
Mark B.

 

Not a bad idea at first sight. But some bad errors might preserve the volume
: thing about a misplaced hole, or a mirrored feature...
Remember, the customer is always right ;-)

 

Feature Works can help verify but you would need both models which I presume
you don't have.

 

The pros and cons about this method is:
If it does show a difference in volumes, you definitely know that there is a
problem.
But if it show the same volumes, that does NOT necessarily mean that
everything is OK. (as Philippe pointed out)

I would definitely use this method first. If it shows a difference, you
know immediately that it was a bad conversion. If it shows the same, that's
a good sign. But you still need to do more investigating.

 

Why don't you use the Geometry Compare function in Utilities? You've
already got it if you have SW Office.

matt

 

If I understand Mark Bannister correctly AND if the customer already
knows the correct volume of the original solids I believe simply
checking the volume in SolidWorks would present a fairly accurate
picture of how good the conversion was. If a solid didn't knit properly
or if dimensions were somehow distorted there WOULD be a difference --
if only a very slight one -- and if the volumes were precisely identical
that would indicate proper knitting and no dimensional distorsion.

I could be wrong . . . but I don't think so.

'Sporky'

 

I think your customer has a good idea, but it may take a little more
than that (as other people have already said).

When comparing models, I compare all the physical property data,
including center of mass and moments of inertia. Even minor hiccups
in translation are readily evident when comparing these properties, as
long as the densities are set the same.

 

The others have had some pretty good ideas about this. My question to you
is: What are you comparing against? What file format are you receiving data
in?

One problem you are up against is how are you going to get the original
volume? If you have IGES, SW has to translate it just to find it's volume.
You might use Rhino if you have it since it is going to leave the data
pretty much alone on translation.

The other thing I would watch for is a file where fillets and other
difficult geometry may have been replaced by surfaces in the original.

If you have the luxury, try bisection when doing volumes. In other words,
compare:

A. Both wholes
A1. Left half
A1a. Left half top
A1b. Left half bottom
A2. Right half
A2a. Right half top
A2b. Right half bottom
and so on. If something is moved you will eventually find it this way. Again
you need a way to do this in both the source system and SW.

Also, benchmark the source system volume calculation with SW.

Also, you could use a system like Rhino to overlay both the original and
translation.

 

Thanks everyone.
The imported files could be coming from anything but are typically
brought in as IGES or STEP. I have noticed with playing around that
getting an *exact* volume match between two systems is difficult. They
are often very close, but I have yet to see one exact to say 4 decimal
places in inches.