How accurate is Revit? Need to rotate a section

[Mike Sealander]

I have a gable roof rotated 33.69 degrees from plan north: that's the 8:12 pitch, but in plan. I put a grid line and reference plane right at the ridge, and cut sections perpendicular to the ridge. Long story short, I'm having trouble verifying that my sections are truly perpendicular to the ridge grid and ref plane, and I'm wondering if Revit is as accurate as AutoCad, or whether it can't compute accurately beyond a certain number of decimal places.

[brakware]

This has been somewhat of a sticking point for me and Revit... the fact that you cannot snap sections and elevations and such to model elements. You can fudge it, but usually it isn't going to get you what you REALLY need.

One thing that you can do is draw down your section line either horizontally or vertically (letting Revit snap it to 90° for you). Then, while the section is selected, rotate it. While you are rotating (before clicking your mouse button), type your angle on the keyboard (in your case, 33.69°, or 90° more or less) and press enter. Then the section will be properly rotated. Unfortunately, you can't, then, snap or align it to your ridge, but at least you will have it at the proper angle.

Good luck.

[sfaust]

Unfortunately, you can't, then, snap or align it to your ridge,
not true. Select your section, go to the move command. Hover over the section head where the section line starts. Hit tab and you will get an endpoint snap at the head of the section. You can then move it snapped exactly to your ridgeline (or anywhere else in your model).

Kind of hidden, but it's in there...

HTH.

Steve

[brakware]

You learn something new everyday, right? Thanks for the tip.

[sfaust]

np. learned it here too from someone else :)

[Justin Marchiel]

good tip.

Justin

[mibzim]

Revit has improved its snapping of section lines to grids and model elements in 9.1. Often its easier to place a new section and make sure it is snapped to whatever orientation you require.

Otherwise use the trick steve suggested. You can also rotate pretty accurately by tab selecting the end points of the section (there is one at each end).

[Tobie]

Same goes for rotating the section. just move the rotation position.

[jvoight]

If you are going to place a lot of sections of anything that have to be perpendicular or parallel to the ridge, one thing i do is set up another plan north to the angle of the ridge.

[patricks]

If you have a datum showing on your roof plan that you know is perpendicular to the ridge, you can snap to the ends of the section line to move and rotate the section, but both ends of the section line must be changed to the tail graphic. If you try to move the section and grab the end handle while it's on the section head graphic, it won't grab it. If you change both ends of the section line to the tail graphic, you can snap to and grab the ends of the section mark line just as you do a wall or a detail line. Then once you get it in place, change one or both ends back to the section head graphic.

So if you have grid lines that are perpendicular to the ridge, place your section at some angle that's close to what you want, and change the head to a tail. Use the move tool to snap to one end of the section line and move it onto a grid line, and then using the rotate tool, move the center of rotation to that end of the section line that is on the grid line, grab the other end of the section line and rotate it so that it's directly in line and on top of the grid line. Now the section is perpendicular to the ridge, and you can move it to the location you need. Then change one end of the section line back to the head graphic.

I just read about this feature last week in the Revit article by Cyril Verley in this month's Cadalyst issue.

*edit* nevermind, the above tip posted by sfaust works also. If you use the tab key you don't have to change the section head to a tail.

[Mike Sealander]

Thank you everyone for your input.
What I found is that it is possible to use the "rotate section" methods mentioned above and get the section (and therefore the view direction) exceedingly close to perpendicular, without quite being perpendicular. This affects the ability to use "mirror", for instance, when the reflection axis is the grid line on the ridge, or a ref plane on the ridge. In other words, if the view is only close to perpendicular to a grid or ref plane, it seems the grid or ref plane will show up in the view, but not be available as a mirror axis. It seems Revit sets a certain tolerance for perpendicular when deciding to show grid lines, and another, more severe tolerance when deciding whether it can use that grid line as a mirror axis.

[patricks]

I don't understand. I was able to get section line exactly parallel to a grid line that was not orthogonal. Are you snapping to the ends of the section line to pick them as I described?

[Mike Sealander]

The problem I had was that it seemed like I had a section perfectly perpendicular to a grid line, but the mirror command did not work when using that grid line from that section. So I rebuilt the section (be deleting the section, then creating a new one), and got the mirror to work.