Polygonal Model/STL feature creation?

[John.Abel]

While IGES and STEP are the bees knees when it comes to pulling primitive features off a model, I'm noticing it is extremely difficult to do so on an STL polygonal model...

is there a best practice for this?  Or is it just time consuming? (i.e. pick and place, best fit, etc.)

[Admin]

John,

I'm a little confused with exactly what you are trying to do.

Are you trying to export complex surfaces from you scanned polygonal model?

[John.Abel]

Sorry, that was really vague...

I figured it out anyway...  I have, as a reference, a perfect STL model given to me by a customer.  This is not my scanned data.
It's a little bit of a pain extracting the features (for GD&T) off a mess of triangles as opposed to having a nice IGES file.

8)

[Firefly]

No other chance than doing it with the 'normal' fitting stuff.

In cases like you described I sometimes start to create all my nominal on the stl just by picking (e.g. a circle with three points), starting with the 'perfect' stl as data object. So I get all my nominal primitves in a fast - not accurate way, but can use the autoextraction to create measured ones. Now the trick: Delete all nominals, switch the measured to nominal primitives and put the previous data stl as reference.  ;D

[PW User]

Here is one other method:
The fit method has a sub-method called "pick then fit".

For a plane, you pick three points (make a plane) and polyworks will look for points with the same normal (within max angle) and within a proximity of the picke plane extended infinitely.

The same method is available for all features. The search distance is by default 1mm around the picke feature.

If you have a perfect STL, it should work.