What's the standard that specifies the size of center marks and when they should be added to holes?

[fcsuper]

What's the standard that specifies the size of center marks and when they should be added to holes on a drawing? Almost every ASME Y drawing with holes has center marks that have a uniform shape, but where is this actually specified. Where is it specified that we should put them at the center of holes? Or, are center marks on holes nothing more than two crossing centerlines that always happen to have the small dash centered in both directions? ...and if so, where's that stated?

Matt Lorono, CSWP
Product Definition Specialist, DS SolidWorks Corp
Personal sites:
Lorono's SolidWorks Resources & SolidWorks Legion

 

[Belanger]

The center marks you refer to are simply part of the larger idea of center lines which intersect, resulting in a cross-hairs image.
According to Y14.2-2014, "Center lines shall start and end with long lines and shall intersect by crossing the long lines or short dashes....The long line portion of the center line may vary in length depending on the scale of the view. Center lines shall extend uniformly and distinctly a short distance beyond the object or feature" (para. 4.7).

Regarding when we should show them, I would say that's a judgement call -- just like hidden lines, which the designer can turn off if he/she thinks it will clutter up the drawing too much.

That's not a specific answer to all your questions, but it's the best I could find here on a Friday evening.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems