Creating a fillet

[Jashe]

I am trying to re-create a fillet from a step model in NX that changes the radius as it moves around the edge of the feature. I've attached a power point showing before & after the fillet was added. Anybody got any ideas?

 

[jerry1423]

The attachment did show up.
What version of NX are you on?

 

[jerry1423]

The attachment did NOT show up.

 

[Jashe]

Oops. Sorry about that. Here it is.

 

[JohnRBaker]

Have you tried using Variable Radius Blends?

But that being said, are those arrows pointing to the 'Concave' or the 'Convex' blends? If you're talking about the 'Concave' blends there may be an easy way to do that using Face Blends and the 'Tangency Constraint' option for the 'Radius Method'. If we're talking about the 'Convex' blends when a simple Variable Radius Edge Blend using the 'Variable Radius Point' method should work fine.

To show you what I mean, see the attached model where the 'Concave' blends were created using the Face Blend method mentioned above whereas the 'Convex' blends were created using the Edge Blend method mentioned above.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[mmauldin]

This may be a silly question, but are you sure the radius changes? Both radii appear as would be expected when applying a constant radius to the geometry depicted. The radius on the shallow end will appear smaller because the relative "angle" between the convex radius and the flat surface is much lower on that end.

 

[JohnRBaker]

Well in that case, a simple Edge Blend using the 'Overflow Resolution' option, 'Roll on Edges (Smooth or Sharp)', will probably do the job (see attached model).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[mmauldin]

It's hard to tell from the picture but "Maintain Blend and Move Sharp Edges" for "Edge Blend (6)" might fit the design intent better. Using this option maintains a more consistent pocket floor.

 

[JohnRBaker]

I guess it makes a difference as to whether the size of top or the bottom of the pocket is critical.

But that brings up an interesting point. With NX 9.0 we've introduced a new function specifically designed to model the blends added to a pocket such as this, based on the actual tool that will be used to cut the pocket, which can be either an 'End Mill', 'T-Cutter' or 'Spherical Mill'. In this case, using a normal 'End Mill', all you need to model, before adding the new 'Blend Pocket' feature, is the rectangular limits or boundary of the pocket skipping the corner blends as the diameter of cutter will determine that size while the radius of the 'bull nose' will determine the radius of the bottom of the pocket. And using this new approach the result is exactly like what mmauldin got using the "Maintain Blend and Move Sharp Edges" overflow option when using a regular Edge Blend. So his approach probably IS the most desirable result since that one will be the easiest to manufacture (which is the whole rational behind the new NX 9.0 'Blend Pocket' function in the first place, modeling what the machine tool will produce). Anyway, good catch mmauldin.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Jashe]

Well I was able to come close by using the "Variable Radius Points". I had to play with the numbers a little bit but it turned out pretty close.