[Questionguy]

Hello,

since January the 18th, I have BC V24. Since that day, I face a problem than I can not fix.
I build up a shape with blended splines. Than I extrude them with extrude curve to get a solid. From that solid, I want to substract a second solid.
I am able to extrude the solid, but most times, I can not substract. I get an error message or both objects disapear. Also if I made an undo, it looks not the same like before.
I try out more simple curves with the blended spline. I stop using the shape I need for my construction. I think the problem is the curve itself. So I made a lot of random shapes with blended splines. Sometimes it works, sometimes even extruding is not possible.
So I think my problem is the way I draw the blended spline. At the beginning, I used an imported 2D drawing to snap in the ancor points of the blended spline. I found out, after substracting a solid from it, that the end of the spline does not look as it should be. So how can I draw a closed loop with blended splines, that I can extrude it to a solid and than later extract something else from it?
A second curve that also did not work, is a curve made of an blende spline breaked by two lines with break many function. I also remove the line later on, an used join to connect the end point of the blended spline. Result is the same. It will not work as it should be.

This problem really drives me crasy. Drawing a curve should be the easiest thing on the world, I am not able to do it right? So please help me.

Greetings

Neil

P.S.: I als ocheck the normals of the solid and try to test different direction.
The blended spline can be marked all with one click.

[dougl]

Hi Neil,

Can you post an example of what you are doing right up to and including the point where it fails. There are quite a few very capable people here who will help if you post your file.

I would bet this has something to do with the curves overlaping or very small gaps (might even be a bug).

Hope we can be of some help,
Doug

[Questionguy]

Hello,

here comes the file.
You must rename it from *.txt to *.bbcd

I have to say something to the file.
I prepare it that only the cylinder must be substract from the extruded part. Before saving the file and reopen it, it did not work. Both parts disapear. Before I attached the file, I test it again. I reopen it, and all work just fine. So this problem you can reproduce.
But please make a new solid by extruding the shape and than try to substract a sphere from it. This will not work.
I saw this in the past. The same procedure get different result based on the file if it was saved and reopend before or not.

Confussed Greetings

Neil

[dougl]

Hi Neil,

I'm getting an "unexpected file format" when I try to open the file.

Are you on the bobcad forum?

Or you could email it to me at dougl at netscape dot ca

Doug

[Questionguy]

Hi Doug,

I just sent you an email with the file.

Greetings

Neil

[dougl]

Hi Neil,

I played around with your file for a bit last night and it pretty much was as unstable as you described.

I have two thing for you to try.

1- Take a good look at your drawing. there are a few left over trims that need to be removed that might be confusing Bobcad a little.

2- When doing your subtract process you might try using a shorter cylinder that doesn't overlap into the other operations space.

Just some thoughts to try. I have found that Bobcad gets real fusssy on some of these seemingly simple things and sometimes is just plain weak on other things like filleting.

Anyway, give it a try.

Doug

[Questionguy]

Hello Doug,

1. Yes I know that and I took care of that. That was the reason why I start to use blended spline. With that I only have one curve made of one object and not many lines and curves with (maybe) some doubles or overlaps.

2. In the mean time, I try to generate the hole thing without blended spline. So removing all the doubles and overlaps. This worked just fine. The thing was ready after 1h. I don't faced any problems during that time. Also the length of the cylinder was okay.

I get the conclusion that all the problems are only based on blended splines. I made a test to see if it is the way I draw them. I draw a lot of splines. Some work some not, but I can not see what I am doing wrong. For the test I only want to generate a surface with a rectangular hole in the middle. Sometimes it generate the surface with the hole and sometimes not.

Thanks for your gelp.

Greetings

Neil