Spline error

[sebw]

Hi,

I try to design two splines that are controlled in two differnt sketches.

Spline Nr.1 is the waterline / bottomline of a surfboard, the other one / Nr.2 is the deckline.

There is associative points (offset along curve) on spline Nr.1

Spline Nr.2 is controlled by the endpoints of lines ( in the same sketch as spline Nr.2) that are coincident to the points on spline Nr.1 and perpendicular to spline Nr.1.

Now, if I want to remove a controll point of spline Nr.1, I get an error message : Internal memory access violation.

I have been in contact with my local UG support and they reported this to UGS, but sofar no answer for quite some time.

Thanks for any Help,

Seb

 

[Xwheelguy]

That's a common error that is sometimes hard to diagnose. Usually even the most experienced UG users end up having to call GTAC. If they haven't responded in a couple of days, call them back...they should have given you an IR number to use.

One thing that sometimes works is to do a part cleanup. Try that & see what happens.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[sebw]

Thanks, for the fast response.

This even happens with only these two splines / sketches in the part. These are the first to construct in the part. So there is not really much to clean up.

Best regards,

Seb

 

[Xwheelguy]

What exactly are associative offset points?

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[sebw]

Dear Tim,

in NX 3 you have associative Points - these points you can place along a curve with a value. This value is changeble afterwards in the expressions dialog.

Like this you can move the points along the spline with a value measured along the spline and not in a straight line.

Best regards,

Seb

 

[Xwheelguy]

OK...I wasn't sure if you were outside the sketch or not. Plus, I don't believe you mentioned which version of UG you were running, but now that you have it (associative points) makes more sense to me.

If I were you, I'd use the Studio Spline versus trying to use spline in sketcher. It's associative & you can constrain each point of the spline with XYZ points as well as constraining the ends as G0, G1 or G2, while also controlling degree & number of segments.

I realize you want a part that will update seamlessly, but considering that it's a surfboard, you'd probably have better luck staying away from sketcher if you're intent on using splines.....just my personal feeling. Plus, NX3 is quite buggy from what I have heard, so that may be making things even more difficult for you.

I've never been much of a user of sketcher....just didn't like the idea of having to put thought into how to "lock" it all down so there isn't unexpected/undesired movement when making a dimensional change. I prefer using what most call "smart curves" or just drawing the curves in modeling in 2D.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[sebw]

Dear Tim,

thanks again for the fast reply.

I ve been working with NX 2 before and I had the same problem. The construction - in NX 2 without the ass. point - cam up with the sam error.

I tried different ways - but no luck.

Reg. Studio Spline - I ve experiementing a little with that.

But can you can controll the slope of the studio spline in a specific point, like you can with a spline in a sketch ?

I ended up constructing the entire " frame " for the board in differnt sketches, and like you say link them all together. Works actually quite nicely sofar.

My goal is to be able to controll as much of the design as possible by numbers/parameters.
I do not want to do to much "freehand editing".

The general things is, that everyboard we make is differnt to the one before. So for me it is important to make the changes fast and easy.

Thanks again,

Seb

P.S: I still got the NX 2 version also running if needed.

 

[Xwheelguy]

Yes you can, but it's usually easiest to use a separate reference line & assign continuity (G1 in this case for slope) from the spline to the line. You could also control each individual point or pole of the spline, really no different than what you're accomplishing in sketcher, it's just a different way of 'dimensioning' it. Also, you could avoid the diffence from one surfboard to another by using 'seed' or start parts that contain standardized geometry already created in them.

I understand your goal for the surfboard (controlling it via numerical dimensions), but the geometry or shapes associated with a surfboard are more freeform than numerically driven.

It's a design approach/preference & not really a fact, so hopefully you'll figure out a method that works for you.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[sebw]

Yes, will try to use the studio spline.

You are right the geometry of the surfboard is more freeform, but never the less you will be surprised how many numbers there are involved to specify those faces.

As you say I am basiclly using seed parts / or previous boards that I change than.

I ve been designing boards for over 15 years now, and just for some time now working it on the computer. So there is a lot of info that has to be fead to the programm.

But like I said before, so far the results are quite good,and for about 4 month I am doing all the design and CAM work with UG, just that internal error is a bit innoying.

For sure I will try the new dirctions you advised.

Thanks again and best regards,

Seb

 

[ewh]

I have to agree with Tim about using studio spline outside of the sketcher. There was a recent post on the UG bbs explaining why.

 

[Xwheelguy]

Rather than steer you completely in a different direction, there is always the "hybrid" approach that you could use which would involve using reference geometry in sketches then taking advantage of more powerful associative curves outside of sketcher (studio spline, bridge curves, etc.) that you could "connect" to the ends of open lines/arcs defined & constrained in sketcher.

I design aluminum wheels & do quite a bit of freeform & Class A surfacing. I have yet to find a method using sketcher that is better than smart/associative curves when it comes to making free form surfaces that are more complex than typical surfaces derived from a sketch. Then again, I don't have your experience making surfboards either.

There also might be other methods of sketching that would be more efficient, such as using reference lines instead the associative points.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[sebw]

Yes, I like the "hybrid" idea - was thinking of that also and will try that.

In the meantime it seems that I have located the initial problem.

It seems the nr.1 spline in the sketch does not like the construction lines ( tangent to the spline and coincident to the ass. point on the spline ) that I use to design the line perp. to the spline.

Even with just one tangent line connected to the spline, the error message comes up.

Is there any otherway to design a line perpendicular to a spline ?

Seb