Sketch Splines - Associative Tangency

[roseda]

Version: 7.5.5.4

Is it possible to create an associative tangency between the end point of a spline and a line?

I've tried these methods (working with two lines angled two each other, one of which is fully fixed and the other has a fix at the spline connection end and an angle dimension to the other line.

Method 1:
Through Points Spline; Degree = 3; no boxes ticked apart from Isoparametric
Pick first end point, right click spline dot and select Infer G1
Repeat for second end point.
Change angle - spline doesn't update.

Method 2:
Through Points Spline; Degree = 3; no boxes ticked apart from Isoparametric
Pick end points - a straight spline is created.
Right click spline dot and Specify Constraint.
Drag yellow ball and snap it onto the other end of the line.
Repeat for second end point (note line has to be in reverse direction to permit snapping to correct end)
Change angle - spline doesn't update.

Method 3:
Through Points Spline; Degree = 3; no boxes ticked apart from Isoparametric
Pick end points - a straight spline is created.
Exit sketch command
Apply tangent constraints.
Sketch goes into overconstraint (red)

Method 4:
The only way I've found is to create the spline in 3D from the lines in the sketch which is not ideal.

P.S. what is a knot?

 

[JohnRBaker]

Are all the curves included in the same sketch? Can you provide your part file(s)?

As for what a 'knot' is, it's one of the data 'points' which defines a spline.

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.

 

[roseda]

John,

The curves are all in the same sketch.

All I did was start a new model, create a sketch and add two lines at an angle to each other with the spline in between the end points.

Maybe it's fixed in a later version.

 

[cowski]

What is it about method 4 that you don't like?

www.nxjournaling.com

 

[JohnRBaker]

Attached is a simple sketch containing two lines and spline created to be tangent to the two lines. If you move the lines the spline will update and remain tangent to the lines.

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.

 

[roseda]

Thanks for your time John.

Your sketch maintains the tangents when the lines are translated. However, if you try to rotate one of the lines by either fixing one end and pulling the other or defining an angle dimension to the axis you'll find it either loses the tangency or becomes overconstrained.

 

[cowski]

Method 4 is your best bet. Studio splines work great outside of the sketcher.

www.nxjournaling.com