Trimming in Rhino

[Willallison]

I'm having trouble trimming a deck surface in Rhino
The deck is made up of two (port and starboard) surfaces. The cabin is made up of 4 polysurfaces - 2 sides and 2 front. The bottom of these have been trimmed off at the deck. I now want to trim off the deck surfaces inside the cabin. When I do this, it says it's splitting, but nothing happens. If I split, it says is can't do it.....
Any help much appreciated.....

[Raggi_Thor]

I sometimes have the same problem.
It may help to reduce tolerances.
Take a look in File / Properties.
Trimming in Rhino is a kind of mathematical loop running till the max error is less than you tolerance, can be funny if you by accident model in meters and have tolerance set to 0.01 for example, that is one cm..

Other tips:
Try in top view, trim with the option "UseApparentIntersections=Yes"
If that doesn't help, create curves along the cabin side bottom, using DupEdge. Then try to trim with that curves. If that doesn't work, it may be easier to make a new sirface from those curves, EdgeSrf.

[Raggi_Thor]

File / Properties / Units, typical settings for small boats...

[Tim B]

Make sure your cutting surfaces extend past the extents of the surface you're trying to cut. I know it sounds simple but it's the top reason for things not working. think of it like cutting cardboard, the bit you cut out must be completley detached.

Tolerances can be dodgy if you don't use them properly. I leave mine in the order 1e-6 and work in meters.

Tim B.

[Windvang]

Copy trimmed sides and front to another place. Then untrim the current front's and sides, make sure they extend trough the surface you want to cut all around. Join al cutting parts and try trimming again. Then replace untrimmed part with copied part.

I use tollerances as Raggi except angle at 1 deg, but I have a powerfull computer.

[SailDesign]

I usually try the "Explode/Trim/Rejoin" method. Just make sure to delete the unwanted parts before re-joining
Also, try creating an intersect curve, and then explode and use the curve to trim.
Both of these have worked well for me when things don't trim.
Steve

[Willallison]

Thanks Chaps - I'll give all the above a try and let you know how I get on. As you can tell, I'm a bit of a Rhino novice - but already I've learned one thing....
Based on your suggestions, it's obvious that many an otherwise productive work hour has been spent wrestling with the nuances of various CAD programs!!

[Raggi_Thor]

yes, that's true, a lot of people spend a lot of time trying to fool different cad programs to do what we want :-)

[SailDesign]

And even more time trying to persuade the programs to do the same thing the next time.....
Steve Baer - are you listening?

Steve (Baker - with a "k")

[Steve Baer]

This may get posted twice. The forum got hung up when I attempted to post the first time.

It is hard to tell from a screenshot exactly why the trim is failing in your specific situation. The techniques presented above are all valid methods to get the result you are trying to get.

Tolerances are an important concept to understand when using any CAD application to attempt to design something that will actually be built. A good short article on Rhino tolerances can be found here:

http://en.wiki.mcneel.com/default.as...olerances.html

We are always listening for suggestions on how to improve Rhino and make it more usable. That is pretty much the point of our open beta process. Just tell us what features or changes you need from Rhino in order to help get your job done.

Thanks,
-Steve