Align Revit to Acad import or link

[bob.86982]

I have tried importing and linking an autocad drawing in my revit model and I'm trying to align parts of my model to the drawing. I can not select any of the lines in the drawing to move my model to or align with. I can place it close to the drawing lines but when I zoom in close it is not aligned. The project is a remodel and the import drawing has corrected as-built walls that I'm trying to align to.

Bob

[Norton_cad]

Move the base cad file away from the desired location, approx 100mm or 4". Then select the Align tool from the menu bar, pick the source, then the object to align (the cad layout), and there you go...

Revit dosn't like moving tiny dimensions, so give it a bigger one.

[bob.86982]

I was able to align the cad file to a common point with the revit model, the problem is then moving parts of the model to align with the lines in the cad file that represent the correct locations of existing walls. Things appear to snap to those lines but when you zoom in they are not aligned.

Bob

[William Troeak]

I have seen this problem before with some other Revit users in an office I used to work in.
What they did if memory serves correct was sent it to Autodesk as a support request.

I don’t think Autodesk came back with an answer but hopefully you can get this on there radar as an issue that needs to be addressed.

[bob.86982]

Thanks Will,

If I don't get some other answers I'll send a support request.

Bob

[hermeytheelf]

are you sure that the lines in the dwg are perfectly vertical or horizontal? That's another thing that Revit can get picky about. Maybe try and import the dwg into a blank project, explode it and check to see how many warnings about 'Line is slightly off axis' you find in the Review Warnings dialog.

[bob.86982]

None of the lines are horizontal or vertical. The lines in this import drawing are the as-built walls of a house that has a center area that is a hexagon and two angled wings coming off of it. To complicate things even more, the house was not built accurately so none of the sides of the hexagon or interior angles are equal as they should be. Some of the hexagon wall lengths vary by as much as a foot. This is a real nightmare to model and tie additions into. I accurately measured the house and laid it out in an autocad drawing so i would have something accurate to adjust my revit model to and now revit will not align to these walls accurately.

Bob

[hermeytheelf]

yikes, sounds like a trainwreck. You would probably be best off creating reference planes by picking not drawing on the lines of the imported dwg. Use the reference planes to align your revit objects to. Make sure you name them so it doesnt get to cluttered and you can choose a specific ref plane from the drop down list when setting your workplane in an elevation or section view.

[steve922542]

None of the lines are horizontal or vertical. The lines in this import drawing are the as-built walls of a house that has a center area that is a hexagon and two angled wings coming off of it. To complicate things even more, the house was not built accurately so none of the sides of the hexagon or interior angles are equal as they should be. Some of the hexagon wall lengths vary by as much as a foot. This is a real nightmare to model and tie additions into. I accurately measured the house and laid it out in an autocad drawing so i would have something accurate to adjust my revit model to and now revit will not align to these walls accurately.

Bob
Bob -
First, be sure that you have pinned the CAD import so that you do not accidentally align it to the model. Then if you still have trouble aligning (which I have seen before) select the item you are aligning and verify that you have not constrained it. You will not always get a warning if it can't be moved. If that doesn't work, try deleting that wall (or other object) and creating a new one using the Pick Lines method on your imported CAD lines.

One thing that you have already noticed is that Revit can give you some odd results when walls are not square. When modeling as-built conditions, this is especially problematic for:

1. Structural beams - many issues particularly with ALMOST linear end to end beams
2. Dimensions - you can not dimension between non parallel walls

With the help of some very patient AUGI Reviteers I got through a nightmarish as-built project in Revit. My solution was to create in-place families for all of the structural components.

I recommend setting up control lines in Revit (ref planes) which you probably did in the field while surveying. In a building which is as non-true as the one you describe, it is really the only reasonable way to model it, or for the contractor to build it.

If you get stuck I'll take a look at it and help it I can. Good luck!