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Setting Precision for a Revit Model

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    Setting Precision for a Revit Model

    Is there a way to set the precision of a model? for example, I don't want to be able to draw an object that is, lets say 5' 6/128" I want it to "snap" to the nearest 1/8 of an inch as it is being drawn.

    I have set the precision for aligned dimensions at 1/8 of an inch but I notice that when I do the "Measure Geometry" tool, I get something different. For example, the dimension will maybe say 7' 1 1/2" but the measure geometry will say 7' 1 35/64"

    This drives me nuts and causes things to be off, and to prevent it, you have to be super meticulous. Is there a way to set this from the beginning?

    To reiterate, I want to be able to draw a wall or object, lets say, and have it "snap" in 1/8th increments, preventing anything beyond 1/8th precision.

    EDIT: I checked my Units, and those are set for 1/32" which is fine, but I am still getting 1/128" precision so that's not the issue as far as I see
    Last edited by katewood1989; September 25, 2017, 09:44 PM.

    Short answer, no. What you draw you get. The units you assign are only altering what will be displayed. If you want a wall to be a specific length, start the first point and enter the length you want. That will never get more or less accurate than your input.

    FWIW, I set my units to the deepest accuracy available 1/256" linear Imperial units. I use dimension styles that apply rounding for display purposes in select situations where rounding is appropriate. I'm also careful to never close dimensions that are using rounding so there is a clearly defined location for where the slop or bust in the dimensional reliability/accuracy is intended to occur.

    You can turn on the grid (Show Workplane) and change the spacing of the grid. Each view has its own. Then you can sketch and snap to the grid. A tiny grid spacing won't be very pleasant to work with though. When/if I use that feature that I assign a spacing that is a multiple of a dimension I'll be calling on frequently, like 2 feet or 5 feet. That way two or three or four grid squares are multiples of the base grid spacing.

    Another way to look at the process, sketch walls without regard for accurate locations initially...just pretty close. Add dimensions and then fine tune the layout by interacting with the dimension values when you select individual or multiple (Activate Dimensions) wall segments to adjust them. Also start with grids and/or reference planes to mark datum locations to add the accurate placement of walls and the rest.


      I do not think there is a way to do that in Revit. However, your question highlights some confusion that some people have about the terms "precision" and "accuracy".
      If one models accurately, then the precision takes care of itself. Revit has a system built in that seems to control the "snap" accuracy based on how far you are zoomed in or out of the view. For this reason, I discourage people from relying on what the temporary dimensions say when they are eyeballing their modeling clicks.
      If they want the thing to be a certain dimension, then they should type it in with the keyboard and then they won't have to worry about 256ths of an inch - ever.
      AutoCAD had a snap system that I tried once for about 5 minutes long ago. Personally, I thought it caused more problems than it solved.
      So to circle back around, I think the answer may be that one needs to be super meticulous.


        jsynder mentioned something I intended to write about too but got distracted so I posted my reply.

        If you open the Snaps dialog you'll find two settings within the Dimension Snaps frame (top of the dialog). The increments that are stored there incrementally affect the length dimension you see as you sketch a wall, a line or move/copy something. When you are zoomed out quite far, far from the model, the the largest value is used and as you sketch as wall you'll see dimensional increments of 4', such as 24' and then 28' etc. (stock settings). The closer you zoom toward the elements the smaller the units are offered. The stock settings are 4', 6", 1" and 1/4". You have to zoom in pretty close to see 1/4" increments being offered while you sketch a wall or a line.

        Similarly when you use the Arrow keys to nudge elements these snap increments affect how far and how accurately they move. Pressing the SHIFT key and using the arrow keys causes selected elements to nudge/move 10x as far as they'd move without having pressed SHIFT. In other words, if pressing the Left arrow key moves a wall 1", pressing SHIFT + Left arrow will move it 10" instead. Again, it is influenced by how close or far you are from the elements in the model. Zooming in closer results in smaller incremental nudges.


          if u type in the length, diameter, angle etc. you will get the exact dimensions your looking for revit rounds things when you drag things out depending on your level of zoom to the object

          the short version of what Steve said


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