Woo-Hoo! Another Standards Tuesday and I am so excited. I hope you have been looking forward to this week’s installment as much as I have been. Last week we began looking into Section 1.8, Dimensioning Features, of ASME Y14.5M-1994 and judging by the traffic it seems to be the most popular Standards Tuesday yet. If you missed it, make sure you go back and read Standards Tuesday – Dimensioning Features Pt1.Today we will continue discussing dimensioning features per ASME such as irregular outlines, spotfaces & knurling. So without any further a due, let us jump right in.

Rounded Corners

When dimensioning corners that are rounded the is no need to dimension the center location of the arc. Instead dimension the edges and the arc radius.

Outline Consisting of Arcs

Sometimes your outline will be pretty complex, made up of nothing but arcs. To dimension an outline made up of arcs first ensure that each arc radius is called out. Then the necessary center locations should then be dimensioned. Care should be taken when dimensioning outlines so that it is not over-dimensioned. There will be times that the location of some arcs will not need to be dimensioned since it’s location is fully defined by it’s tangencies.

Irregular Outlines

Irregular outlines can be extremely troublesome to dimension. An irregular line can be made up of a spline that can’t be dimensioned by conventional methods. Instead, the best way to do it is to place points on the line that can then be dimensioned coordinately. I find ordinate dimensions work best for this situation sense it is often cleaner, but that is a personal preference. ASME Y14.5 also allows designating each point with a symbol, such as a letter, that is then referenced in a table. This was great in AutoCAD or manual drafting but I do not encourage it in SolidWorks, since as the outline changes the values will not be updated in the table.

Symmetrical Outlines

In my opinion, this is one the aspects of ASME Y14.5 that really doesn’t apply in today’s CAD world. In the past when drawings were hand drawn, a great time saving practice was to only show one-half of a large profile that was symmetrical. The centerline for symmetry designated that the unseen portion of the profile was a reflection of the shown outline. The profile centerline was then designated for symmetry with two thick horizontal lines, looking like a an equal sign, at the top and bottom of the centerline. Refer to ASME Y14.2M for more information on this linetype.

Round Holes

The illustration below shows how to dimension a round hole. When the depth of the hole is not obvious then it must be dimensioned. If the hole goes through the entire feature then the abbreviation of THRU may be used to follow the diameter. When the depth is a blind depth, most of the time you can get away with using the depth symbol shown below. If the depth is not clear, as when you are dimensioning a hole on a cylindrical face,  specify the depth with a dimension.

Slotted Holes

Slotted holes can be dimensioned as shown below. If using the DimXpert, each of these methods are supported. However when dimension by using conventional methods you may find the Ex. 1 & 3 are easier.

That will cover it for today. I realize it is extremely short but to be honest I ran out of time. Next week, I will make sure that my continued converage of ASME Y14.5 is a lot better. Hey, it’s like they say it’s not the quantity, it’s the quality.

If you enjoyed this post, make sure you subscribe to my RSS feed!

Related posts brought to you by Yet Another Related Posts Plugin.