'curves don't form a closed boundary'

[Mark Lovelace]

Every now and then, I'll be trying to trim a surface to a curve and I'll get the message "Selected curves do not form a closed boundary", when they in fact do. This is one of those times. I've tried extending the curves well beyond the surface, retrimmming the composite arcs, and all of the options under'modify/trim/surface/to curves'. Nothing will convince Mcam that that this is a closed boundary. What am I missing here?

[perfecseal mankato]

this is just an idea I have used in the past.

try extending the surface in all the directions

before you trim it. sometimes the geometry is correct but the surface may not cross the geometry

so it cannot be trimmed.

[Mark Lovelace]

I've tried that, but when extending this surface develops a self intersection, which causes other problems.

[Roger Peterson]

try doing a xform squash on your trimming curves.

[camguy]

Mark, I have had the same problem with this also. If you are set to "normal to cplane", try changing 'normal to surface". If this does not work, run "rmnodes" chook and pick any splines that are in your trim curves to reduce the number of node points in the splines. This works 99% of the time. Hope this helps

[Mark Lovelace]

Tried this, tried that. My trimming curve doesn't have any splines. I's all tangent arcs and lines.

 

However, I did get the surface to trim, but I had to redraw the surface itself. I changed the orientation of the coons patches (from along to across), and for whatever reason that seems to have accomplished it.

 

Thanks for all of the suggestions. If anyone knows why this worked, or what the actual problem was, please let me know.

[cadcam]

Mark I would liked to seen the first file to of tried a few thoughts.

Whats the chance.

[cadcam]

Mark I would liked to seen the first file to of tried a few thoughts.

Whats the chance?

[Zero]

That's what I usually end up doing if nothing else works. MoldPlus has some good powerful trimming tools that work when mastercam sometimes wont. I have never tried the rmnodes chook, I'll have to see if this works next time.

[BernieT]

This thread has some more info on the same subject.

 

http://www.emastercam.com/cgi-bin/ultimate...ic;f=1;t=003596

 

BerTau

[Die Sinker]

When I have trouble like this, I do "Modify, X to Nurbs, Surfaces". Click the surface, then trim. It has worked for me before with "seemingly difficult to trim surfaces". It has been a while since I needed to do this, but someone else might have used this as well. Try it. It can't hurt. But, as others have stated, get the construction plane correct.

 

Gary Armitstead

Santa Fe Enterprises

Santa Fe Springs, CA