Making effective dimensioned drawings is an art. It's not so easy to figure out what dimensions are needed and how they should be displayed. I'm always impressed by drawings done by John Kassay in his book, "The Book of Shaker Furniture" or Lester Margon in his book "Construction of American Furniture Treasures". They produced works of art, while communicating the engineering design in an efficient and effective way.
In SketchUp it's easy to splash a drawing with a bunch of dimensions, but they don't always look that good. So I'm finding that it is taking me much longer to do dimensioning in an effort to improve. Getting the SketchUp model assembled is perhaps only 75% of the job. Another 25%, or maybe more of the time is making and editing dimensioned Scenes.
Although I use Layout to produce the final drawings, my dimensions are done in SketchUp. Layout can do orthographic dimensions, but it currently does not manage perspective dimensions. I think it is important to have both perspective and orthographic dimensioned views. Flat dimensioned drawings are easy to make, but aren't sufficient for communicating work in the shop. The best drawings I see have both representations.
I'll show you some of the things I've found helpful in placing dimensions. I'll use this Stile and Rail with mortise and tenon joint as an example.
In the above picture I've used a dimension style that includes:
Endpoints - None (you could also use arrows, slash, or dot)
Align to Screen
These options are found in the Model Info Dialog Box as shown below. To find this dialog box, click on the Window tab, pick Model Info from the list, and then click on Dimensions in the left panel.
If you select the option "Align to dimension line" in the dialog box, the same drawing will have dimensions shown below. Note that some of the dimensions are now unreadable. Clearly, the "Align to Screen" setting is better in this case.
Also note that many of the dimensions are shown with the dimension text outside and at the end of the leader lines. I find that this option is used often because the dimension is smaller than the text. To make this setting, right-click on a dimension and a menu will pop-up as shown below. I've right-clicked on the 3/8" dimension, then I move the mouse down to Text Position that opens up a fly-out menu with three settings. In this case I've used Outside End.
Often I need to change a setting for a specific dimension. After you click to select a dimension (13/16" in this case), right-click on the dimension and pick Entity Info, and a dialog box will appear as shown below. Here you can change the setting for that particular dimension. I use this sometimes to switch the alignment or change a font.
I place dimensions in layers for the flexibility of having only some dimensions showing in a scene. In this case I have a close-up detail perspective view of the stile and rail joint. The dimensions shown here should not display in a scene showing the entire stile and rail assembly. Therefore I select all the dimensions and choose Detail View Dimensions/Text in the Layers Toolbar. Also I set visible layers for that Scene as shown in the Layers Dialog Box to the right.
After placing dimensions, I often spend time nudging and moving them for best viewing. Choose the Move/Copy Tool and hovering over a dimension. It will turn blue (selected) and you can begin the move. However, sometimes the movement is very jerky and jumps further than you would like. To have more control on movements, I sometimes use the Select Tool to select the dimension, then click the Move/Copy Tool on an edge anywhere in the model (but along the axis of desired movement). Now when you move the mouse, the adjustment of the dimension is more smooth, incremental and controlled.
The following picture shows that I've selected the 13/16" dimension and clicked the Move/Copy Tool on the top edge of the stile. Now a movement of the mouse along the edge will shift the dimension accordingly.
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