Sketcher and Expressions

[JTDillard]

I am needing some help on a part as quickly as possible. I am trying to make make this model in NX4 4.0.0.25 but I need to to use sketcher and build in expressions so that when I change a radius or length ect... the whole part updates and does not blow up. I have the whole part modeled up and expressions built in how I am thinking it should work but I think there are some constraints not in place that need to be or something because it blows up. If I change the R45. to R55 in the extrude cut all of the lines go everywhere. I also have expressions built in so when a dimension changes on the extrude cut the same dimension will follow on the revolve cut. I have not used Unigraphics in a while so I am getting rusty with it. My last job I was using Solidworks and I wouldn't have a problem doing this. If someone could show me what I am doing wrong I would greatly appreciate it.

Thank you,
JT

 

[JohnRBaker]

Is this what you were looking for?

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[hudson888]

JT,

The co-incident end points of the lines weren't constrained as such, one line was fixed which stopped the sketch from working and there were a couple of other constraints that I rebuilt before coming to an equivalent result to what John had.

Cheers

Hudson

 

[JTDillard]

I really appreciate you guys helping me out. I should have uploaded the print as well. I can't figure out how the 5 sharp corners of the star became flats. It doesn't look like any of the dimensions were changed from what I had. The print shows sharp corners, what would have changed this? Thank you again for the help.

 

[JTDillard]

Nevermind I see it now p85 is 55mm causing a flat. I feel like an idiot now. Sorry.

 

[JohnRBaker]

No, the issue was that you had fixed one of the lines as well as the arc. I suspect that you were trying to keep the arc from moving, which fixing it will prevent, but it also prevented it from changing size. The better approach is to constrain the center of arc to match the center of the rotational feature, which is what I did.

I would suggest that you try and avoid using the 'Fixed' constraint if you expect the curve to move or change size. Fixed is fine for reference curves that are not part of the profile of curves, things that you measure FROM but not things that ever need to update themselves. When a curve is fixed it will NOT move or change size even is you edit driving expressions, like the radius of the arc in your original Sketch. Remember, FIXED means FIXED!

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/