Spline problems

[SiW979]

Hello everyone.

I'm messsing around with splines at the moment doing something which should be relatively simple, however the outcome is a little problematic. Have a look at the attached model, there are 3 splines 2 of which are over built and spline 6 is attached to the other 2 with G2 continuity using the point on curve snap associativity in an attempt to give me a smoothe path I can use to make a trimming sheet. However, as you can see by the extrude feature, there are breaks in the surface. I have tried using law extensions, reducing the modelling tolerance, using the stop at intersection and follow fillet options, but I'm not able to create a perfectly smooth sheet. I was told that over building splines (and sheets) was good practice or am I missing a key piece of info? Perhaps someone could explain where I am going wrong please?

Many thanks

Si

Best regards

Simon NX7.5.4.4 MP8 - TC 8

http://www.jcb.com

 

[vrishraj]

Simon,
My guess is the curve intersects at more than one place which is very close to the end point, check information point and select end as well as intersection point.

Raj
NX 7.5

 

[MickyV007]

Yes Raj,

you're right. If i make a sketch and project the splines Simon has created with the 'stop at intersection point' option you will get a continuous curve.
But the question remains why does NX can't create a spline that starts and stops at the designated two other splines, I've tried it with bridge curve also but got the same result.


Best regards,

Michaël.

NX7.5.4.4 + TC Unified 8.3
Win 7 64 bit (Intel(R) Xeon(R) CPU X5650 @2.67GHz)
24.0 GB
NVIDIA Quadro 4000 + NVIDIA Tesla C2050

 

[MickyV007]

Simon,

i was able to reposition your endpoints of the third spline, onto the two other splines with the point on curve constraint. Then increased the tolerance on the extrude from 0.001 to 0.01. Acceptable as a solution?

Best regards,

Michaël.

NX7.5.4.4 + TC Unified 8.3
Win 7 64 bit (Intel(R) Xeon(R) CPU X5650 @2.67GHz)
24.0 GB
NVIDIA Quadro 4000 + NVIDIA Tesla C2050

 

[cowski]

Overbuild and trim is one modeling strategy; if you go this route, you will, by definition, need to overbuild the sheets. To that end you will need to overbuild the spline that contributes to the sheet creation. I wouldn't bother overbuilding portions of the splines that don't contribute to the sheet. You will have an easier time of it if you define those 2 splines to where you need them and constrain your transition spline to the end points.

www.nxjournaling.com

 

[CNSZU]

I see there are 2 gaps in the extruded surface, so what I did was simply redefine the extruded feature, deselect and reselect the 3 curves, and everything is fine. Maybe it is simply due to the difference in NX versions.

I any case, I suggest you use a better method. Forget the 3'rd middle curve, instead use your two overbuilt curves to create an extruded surface with "Stop at intersection" rule to create a corner. Then create a Aesthetic Face Blend or Styled Blend to blend the two faces. This method has two main advantages, 1st that the blend is associative, so any adjustment to the overbuild curves and the blend will update itself. 2nd is that you have easier control over the shape of the blend surface to create an ultra smooth transition between the faces.

NX8.5 Win7SP1 64bit i7-3770K@4.3Ghz 16GB Quadro2000

 

[SiW979]

Thanks guys

Si

Best regards

Simon NX7.5.4.4 MP8 - TC 8

http://www.jcb.com

 

[Toost]

Without any comments on working methods, i tried the supplied model in NX7.5.5.4 and 8.5.0 .
7.5 does the gaps while 8.5 does not.
- Time for an IR...

Regards,
Tomas