logo
NOTICE:  This is the new PunchCAD forum. You should have received an email with your new password around August 27, 2014. If you did not, or would like it reset, simply use the Lost Password feature, and enter Answer as the security answer.
Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error
Rail extrude question (#305)
Options
Go to last post Go to first unread
Previous Topic Next Topic
rojharris  
#1 Posted : Wednesday, May 30, 2007 1:57:05 PM(UTC)
rojharris

Rank: Junior Member

Joined: 5/28/2007(UTC)
Posts: 15
Hi There,

I am a complete beginner with nurbs and I am having some frustrating difficulties doing what would seem to be a simple operation. I have bought ViaCAD (because it seems amazingly powerful for its price) mainly to model bottles (my client is a bottle product designer). Now very few of these bottles are your basic revolved profile round an axis critter. Usually they have different x and y dimensions, like an elipse. So here's what I'm trying to do:
I draw a cross section, like an elipse for eg. then I procede to draw the profile of the height of the bottle, starting with the recessed base bit, then down to the bottom, then out a bit, then up the side to the top, then in for the neck, then straight up then finish (with an interpolated spline). When I try to use rail extrude to skin the bottle shape I always get a "self-intersecting" errror.
How can I avoid this? Should I always use cross sections and skin them (but then how to get the domed recess in the base)?
This is very frustrating as I am sure there must be an easy way.

Here is a grab of a profile so you can see what I mean.

Any pointers much appreciated. I can't believe I'm stumped at the first hurdle on this one!

cheers
Roger
UserPostedImage
Back to top
WWW
rojharris  
#2 Posted : Thursday, May 31, 2007 2:18:33 AM(UTC)
rojharris

Rank: Junior Member

Joined: 5/28/2007(UTC)
Posts: 15
OK. I've figured out, by looking at other software methods, that what I need to do is a 'boundary sweep'. Can I do this in viaCAD?
Back to top
WWW
jlm  
#3 Posted : Thursday, May 31, 2007 11:54:33 AM(UTC)
jlm

Rank: Senior Member

Joined: 2/18/2007(UTC)
Posts: 1,252
Man
France
Location: Paris & Frankfurt

Thanks: 217 times
Was thanked: 164 time(s) in 101 post(s)
Rojharris,
You're right, it's difficult to make it !
I tried all the methods I could think of to make a similar shape (one or two rail sweep surface, one or two rail sweep solid, solid skin with guides, guide skin surface...).
They all failed.:mad:
"self intersecting or cusping surface found".
I'm sorry, it doesn't help...

Hey Punch people !
What is cusping ?

JL
Back to top
WWW
jlm  
#4 Posted : Thursday, May 31, 2007 12:42:25 PM(UTC)
jlm

Rank: Senior Member

Joined: 2/18/2007(UTC)
Posts: 1,252
Man
France
Location: Paris & Frankfurt

Thanks: 217 times
Was thanked: 164 time(s) in 101 post(s)
Though, if you need to make this shape, use a set of ellipses (ie the one you have + a bigger one at the base + 2 for the body + one for the neck) and use the simple skin solid tool.
You can change the ellipses parameters afterward and get a very smooth solid.
I used this method for a few shampoo bottles.

The nurbs nerds should still fix the cusping :rolleyes:

JL
Back to top
WWW
rojharris  
#5 Posted : Thursday, May 31, 2007 1:54:47 PM(UTC)
rojharris

Rank: Junior Member

Joined: 5/28/2007(UTC)
Posts: 15
Hi Jim,

Thanks for the reply. I did make it with skinned elipses in the end, although I found it difficult to get the top nice and straight. Sometimes it's better to be able to define a clean profile so it's exactly what the design specifies, so I agree that this should be fixed! It would be ok if we could make it from cross sections and then afterwards edit a profile curve but I couldn't get that to work.

Of course this would be a doddle in sub-d's but then that's not the point.

cheers
Roger
Back to top
WWW
jlm  
#6 Posted : Friday, June 1, 2007 12:07:10 AM(UTC)
jlm

Rank: Senior Member

Joined: 2/18/2007(UTC)
Posts: 1,252
Man
France
Location: Paris & Frankfurt

Thanks: 217 times
Was thanked: 164 time(s) in 101 post(s)
rojharris wrote:
Hi Jim,
I found it difficult to get the top nice and straight.
Roger

Roger,
Then, make the top part with another solid (cylinder or extrude), boolean add and blend the junction.
JL
Back to top
WWW
Users browsing this topic
Guest (3)
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Powered by YAF.NET 2.1.2 | YAF.NET © 2003-2024, Yet Another Forum.NET