Linear scaling of sketches

snipped-for-privacy@tagaerospace.com (Phil Evans) wrote in news:jOadnXABp6- Fjz_anZ2dnUVZ snipped-for-privacy@giganews.com:

I'm not aware of a feature or other tool that can do this. The only way I can think of involves some shenannigans with projections of derived sketches from angled planes.

C'mon... non-uniform scaling for sketches has been a request for well over 5 years and almost exactly a year ago and it was discussed like it was something new!?!?!?!?

Silly me, I digress,.... why would anyone need this when we can clearly workaround this issue!?!?!

.. maybe export to Autocad or Rhino and do a non-uniform scale.... YEAH, THAT'S the way to do it!?!!?....what a joke.

The stupid long time workaround is to extrude your sketch(s) as a surface and using the body scale, copy the edge(s) of the surface and break the link.

NOW, isn't that a super productive workaround,.. why do we need a that dumb non-uniform scale thingy.. aren't workarounds in SolidWorks the best!?!?!

Hmm,.. let-me-see,... this will someday be a new user enhancement in

2011, right!?

..

I guess that means NO!!! :-)

I can do it in 2004 by turning the sketch into a planar surface and scaling that.

HOWEVER, as has been pointed out, that is a kludge, workaround, extra steps, avoiding the real issue, blah.......

There is one big factor that makes it different in a parametric, feature based modeler. In ACAD, the sketches are dumb. In SW, after they are created the solids and surfaces are dumb so both can be scaled. It is the sketches that are smart, i.e., they have dimensions and relations so you have to differentiate scaling before and after applying dimensions and relations to a sketchs. There is a tool in the sketcher that will scale an unconstrained sketch in both directions. But it doesn't work when the sketch has any constraint because you can't back drive the constraints in a meaningful way. Similarly, if you didn't notice, after applying a scaling feature to a solid, the reference geometry that originally defined the solid doesn't scale. How do you scale design intent? It might be nice to be able to scale an unconstrainded sketch but you would be hard pressed to integrate that scaling parametrically to the rest of the model after applying dimensions.

TOP

Paul,

It goes beyond 2D planar sketches.... 3D Sketches are also needed! I really don't see the issue with sketches which have driving dimensions and constraints.... they will obviously have to LOOSE them for the non-uniform scaling to occur!

It's a SIMPLE request which takes a BOAT LOAD OF BS TO HAVE IT BECOME A REALITY!>?!>?!>!>!>!>!

..

And we first want stability of the program and NOT new features . . .

TRUE TRUE TRUE. Besides what would the purpose of scaling sketches be anyhow. I've never had to scale sketches in SW. I've scaled the solid model but have found no use for scaling sketches

Willem1 wrote:

I guess the fact that I have asked how to do it means there is a purpose, I dont ask questions if there is no purpose!

In this particular case I have an airfoil spline that is controlled by XY data points. It is very common to stretch and modify airfoils in only one direction to get flow/lift/drag characteristics in that direction. I can of course replicate the spline by applying a scaling factor to the X coordinate but as there are 200 points in the spline this is quite time consuming.

Phil,

Ya-know... I was being obviously facetious and serious and the reason is/was because you asked this same question well over 4 years ago,...

Now, you would think that you and others would be thinking... hmm,... now why doesn't SW have a non-uniform 2D and 3D sketch option when other similar programs have had this for well over.... 8 years,.......!?!?!!? Makes you go,... HMMMMMMMMMMMMMMMM?

Oh well,.. silly me, it's one of those extremely obvious things that the people at SW Corp and it's users can't seem understand?

..

So do you use an Excel Spreadsheet to "spread" the points (sorry for the pun) and then plug the new data into SolidWorks?

Bo

yes.

I then save it as a text file and import it as a curve thru XYZ points. Its not a major deal but it is repetative iterations that cause the time headache.

A Harrods sales assistant was asked if they had a certain Wedgwood coffee set in blue, she replied "No"

A couple of hours later she was asked the same question by another customer, again she replied "No"

Just towards the end of the day a third customer asked her if they had this coffee set in blue, once again she replied "No"

This time the customer asked her why they did not have the coffee set in blue.

The sales assistant told the customer that there was no call for it!!

Right now you have to lose the constraints any time you scale. So you lose the parametric nature of the sketch including possibly any clear reference to underlying geometry. This sounds more like a Rhino or ACAD way of doing things.

On the other hand there is a clear application to use geometry that has been non-uniformly scaled with dimensions and constraints if you are doing shrinkage in castings, molded parts or rapid prototypes and want to carry the dimensions along for the pattern.

TOP

The most common thing in the plastics world is when you are molding Polyethylene & Polypropylene, where the radial shrink is different than the linear shrink. Thicker sections shrink different than thin sections.

I can see though that tackling this "non-linear" problem in the "Cavity" tool of SolidWorks is one which is NOT trivial. It would be nice if it were in the bag of tricks, but that would require a database of materials and algorithms to feed info to Cavity tool.

Given the subtle improvements in SolidWorks, maybe we will get something like that eventually.

I watched the demos and talked with some of the SolidWorks demo guys at the Anaheim MD&M show last week and have to admit I like a lot of the new stuff in SWks 2008.

Bo