how to create surface radiating from edges ("Radiate Surface")? 3

[potrero]

NX6.0.1

Is there a way to create a surface radiating outward from edges on a body? This might be useful in design of mold tooling; for instance, one could create a mold split line on a part, then "radiate" a surface outwards from the split line, and use the surface to split the mold tooling.

This would be similar to the "Radiate Surface" functionality in Solidworks.

 

[potrero]

for an example of what I'm referring to in Solidworks, see this link:

http://www.theswgeek.com/2008/10/15/splitting-parts-revisted/

 

[Xwheelguy]

Seems to be quite similar to Law Extension, found on the Surface toolbar.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[cowski]

Are you looking for something as simple as the egg example, or is your part more complex? Can you post a jpeg of your model?

 

[hudson888]

You could use a law extension or angle extension surface types to create a surface or more likely a series of surfaces defining the split line of a tool or die. Take care that surfaces around tight corners are seldom straighforward much less easy to do well. Nor does Solidworks produce ideal examples from what I've seen. Sometimes you're better to accept the extendsion surfaces that meet your edge to edge tangency requirements and build the few corners that cannot using curves and mesh surface types.

Cheers

Hudson

 

[potrero]

Law Extension is what I'm looking for. There are so many useful tools in NX; it's really fun finding them and learning what they can do...

 

[hudson888]

Okay but the tempation with law extension is to combine the output of edges running over multiple surfaces into a single sheet. If the edge curve continuity is poor so is the result and it is seldom if ever advisable to go around corners using such techniques.

Cheers Again

Hudson

 

[PepeCompany]

Sorry by the delay, but I'm new forum user.

When a need a surface like you are looking for, I simply extrude the part contour along the Z-axis and with an "outside" offset value as long as you need (the extrude lentgh is irrelevant). Then extract the top surface of this solid body.

You just need a clean smooth contour with no loops and no sharp edges.

I think this can solve your question.

 

[potrero]

Hudson,
I've found that a reasonable set of methods to handle situations where you've got multiple faces or corners is to use separate Law Extensions, and then "fill" the leftover with either Thru Curve meshes, or possibly an N-Sided surface. Bridge Curves are useful to create the outer boundary for such "fill" surfaces.

 

[hudson888]

Sounds like you're on the right track then.

Sometimes in building an extra surface around the corners it helps to be able to use those surfacing tools to force tangency. Everyone generally likes to have a smooth continuous split line. From experience you also learn to also use the graphical displays in the surface analysis tools to spot any areas where the minimum radius of a surface is smaller than you would easily be able to machine.

Cheers

Hudson

 

[uwam2ie]

... why so complex
use the ribbon builder ( ribbon sheet)
so easy

 

[potrero]

uwam2ie - Wow, Ribbon Builder is pretty nice. Not sure why I hadn't tried that before...
Thanks!

 

[hudson888]

By all means use the ribbon builder if you can get it to work. I find that in some simple cases it has been known to work, but for anything else I find myself going back to surface building simply because we generate the split lines normal to the surfaces in a lot of cases and the single vector method doesn't give us the shut lines that we desire.

If the split line was planar then you could even create a bounded plane. Which is to say similar to the result that ribbon builder generates for a planar split line. If you're happy to have the split line radiate normal to a vector, but the shut line itself goes up and down in 3D then ribbon builder will often either do the job or generate 90% of the surfaces needed requiring you to rebuild only some small portion in order to improve either minimum radius or tangency conditions.

With any technique that you use check your results and don't necessarily expect to system to achieve good tangency between the edges. Usually the quality of the curves and surfaces that you use as inputs has a lot to do with how well the results come out.

Cheers

Hudson

 

[uwam2ie]

@ hudson,
ok you are right most cases it is not so similar , but we started the thread with the SW example.
But also long term UG users did not use nice approaches.
You are talking about bounded plane - I have used it it older versions, now I use extrude start end point to zero (think about the selection intend - much faster). But control the results in freeform - a lot of mess can be done for eample with n-side surface...

 

[potrero]

@ uwam2ie,
i think it's good for this thread to evolve, at least the way it's going so far...

Can you expand on your comment about Bounded Plane being less preferred than Extrude with Zero start point? (Would you then use the start face as the "effective" bounded plane?)

Also, what sort of problems typically arise with N-Sided Surface?

 

[hudson888]

The case for the bounded plane at a split line is simply that the other methods will generally result in an outer perimeter as an offset following the shape of the inner perimeter. This has serious limitations if any concave corners exist along that perimeter. In addition the tool is most likely to be either circular or rectangular in shape and it is simpler with the bounded plane construction to create a face which contains an outer perimeter matching the shape of the tool.

The zero extrude is a technique I hadn't thought of. I'm fairly sure it wouldn't work well with other than planar split lines. I simply think it isn't designed with that application in mind and has some serious limitations. In that regard the ribbon builder is a better tool.

N-Sided surfaces are generally speaking a rough construction tool with fewer and poorer controls than the other mesh surfaces. I doubt that the kinds of boundaries of which we speak ever lack the geometry to support being more carefully built with a curve mesh surface. I simply fail to understand why you'd need to use an n-sided surface for a split line. So called experienced users ought know that there are better ways.

Cheers

Hudson