In SolidWorks 2007 drawing mode, the ability to change the size of individual dimension arrows (so that they were different than the drawing) was limited to a tricky use of favorites. Starting with SolidWorks 2008, that situation improved. SolidWorks now allows the user to set the size for individual dimension arrows. For me, using arrows of a different size from the drawing default was only required once in the past. However, I recently had the need to use this function for dimensioning limits from an origin. This is a special kind of dimension where the tolerance of a dimension is set between two features but applied in only one direction.
From paragraph 2.6.1 of the ASME Y14.5M-1994 standard:
In certain cases, it is necessary to indicate that a dimension between two features shall originate from one of these features and not the other. The high points of the surface indicated as the origin define a plane for measurement. The dimensions related to the origin are taken from the plane or axis and define a zone within which other features must lie.
The origin of such a dimension is shown by replacing that arrow with a circle.
This is where we get back to talking about SolidWorks. You can change the shape and size of the arrows on one or both sides of a dimension. The problem is that once the dimension arrow is changed to a circle, its size cannot be adjusted. This means that if the circle is too small (as it likely will be) the size must be changed to the arrow before switching it to a circle.
The following are the basic steps to establishing a dimensional limit related to an origin on a drawing in SolidWorks 2008 or higher.
This following chart will then pop up at that location on your drawing view.
3. Select Size, to bring up the next window.
4. Deselect Use document arrow size and edit the arrow width. Accept by choosing the OK button.
No, you aren’t done yet. There’s more. Remember, earlier I said the situation was easier. I didn’t say it was easy.
7. Select the fifth item down on the pop up chart, which is the circle at the end of the dimension line.
After all of this, you’ll finally have a dimension that establishes its tolerance from an origin per ASME Y14.5-1994 paragraph 2.6.1 and figure 2-5.
UPDATE: Newer releases of SOLIDWORKS will allow you to apply a size directly to the circle arrow. So, although the above instructions still will work, there are some extra steps that are no longer necessary.
Thanks for the great tutorial.
Thank you, tool die design. My only complaint about my own tutorial is the image quality on Internet Explorer (IE). I’m using some high res photos and are properly handled to make them display properly…however IE cuts them up badly. Firefox isn’t much better. It’s just that the internet programs aren’t really supportive of images with this orthogonal lines. I’m working on a solution.