voids and solids not getting along well...

[danger3sque]

I've almost finished carving out a mass but am running into some really strange issues. I've found that if I create a void that doesn't intersect the solid but then move it to overlap with the solid, it won't cut the solid. Using the 'Cut Geometry' button doesn't help. However, sometimes if I draw over the blend profiles of this void (one that is properly placed to overlap the mass) and create a new void form, it will cut the solid without a problem!

Some void pieces just don't seem to want to cut my solid. So far I've had limited success with breaking the voids up into simple, smaller shapes. I've looked over the user guide and various tutorials but it seems like it should be fairly straightforward. Are there some unwritten laws about revit massing that I should know?

[Steve_Stafford]

It's a chicken and the egg thing :)

If a solid is created first and a void is created, when you click Finish...if they intersect Revit will cut the solid. If you finish but it doesn't intersect, no cut. Revit doesn't assume it should cut if you haven't created the situation to allow it. No worries, you can use the Cut Geometry tool (Modify ribbon) to tell Revit which thing should cut which other thing(s).

Interestingly, if you alter a void that's been told to cut a solid so it no longer intersects and then move it back, it remembers it is supposed to cut. This means you can create an "on/off" condition by parametrically moving the void in and out of contact with a solid.

[danger3sque]

I will definitely keep the on/off void tip in mind for the future!

As for my problem, these are actually voids that I've created after the solid. I basically have a big solid that I've been carving away at with voids. If I create a void form that doesn't initially intersect with the solid, Revit seems to blacklist this void and won't allow it to do anything. Moving it to intersect with the solid and/or editing the profile to simplify it doesn't seem to help. 'Cut Geometry' doesn't seem to do anything. The only voids that I've had any success with are those that intersect the solid when I initially create a form from the profiles.

[Steve_Stafford]

Are you a project? If so the voids have to be in the same "family". I assume you are using an in-place family. You need to edit that family and add the voids. If you are in a family template then the cut geometry should work.

[danger3sque]

Yes I'm doing all of this within the edit-mode of an in-place mass family

[Steve_Stafford]

If I may ask, what are you making with the mass category? Building form or something "real"? I ask because I see people use it for the wrong reasons and regret it later because they really meant it to be a wall or floor or something else.

Do a little test. Start a new in-place family, create a new solid and void apart from one another. Drag the void so it intersects the solid and then use Cut Geometry on it. Should cut.

[danger3sque]

Thanks for the help so far by the way. I'm modelling a building envelope that has a somewhat complicated form. I need better control over the curtain system than what an imported mass would give me, so basically I'm just trying to remodel the imported mass in Revit and then divide the surfaces by intersection to come up with the curtain grid. See here for some images: http://forums.augi.com/showthread.php?p=1140229

I did a test like you suggested and it works fine with a new in-place family.

As for my problematic mass, I found that I can create a non-intersecting solid or void, drag it across the solid, and then toggle it to a void and it will cut. Somehow this works while 'Cut Geometry' does not. I guess this is a so-so workaround but I hope someone knows why it's not working normally.

The last void I need to have cut from the solid won't cut though. Sometimes it will throw errors about causing elements to unjoin. I'm guessing this is because it's cutting through some unusual geometry (at the bottom on the front where one surface peels away from another). I'll try to keep breaking up the void into smaller pieces and see if that helps.

If you want to have a look I'm attaching a simplified version of the project with just the mass. The small form jutting out in front is supposed to be the last void cut away (only a small chunk). To the left is the imported mass and to the right is the original void I was trying to cut the whole bottom-right portion with.

[danger3sque]

I continued dividing up the voids into smaller pieces until I isolated the portion of the solid that doesn't seem to want to cut no matter what (circled in the attached image). The green profile is how the bottom surface should look (basically a blend between the adjacent surfaces). Also, can that line above that I x'ed out be removed, that is, make that whole blend continuous instead of faceted?

I know this isn't a major deviation from the desired form but I don't see why Revit shouldn't be able to do it. Any ideas?