yang686526

dimensioning repeated hole patterns
i'm attempting to dimension a drawing of a large plate (lots of holes) and am trying to find ways to avoid the inevitable mess of crossed dimensions. there is a pattern of 4 holes that repeats in about 10 places and i was wondering if there was a way to create a detail of the pattern and reference that detail 10 times. i can then dimension 1 hole for each pattern and refer to the detail.
does that make sense? any help would be appreciated, thanks.
i've seen that done before. i do not think it violates any standards. have you considered a hole table?
"art without engineering is dreaming; engineering without art is calculating."
i considered a table but my real intent is to show that the dimensions within the pattern is more important than the location of the pattern. i was hoping that by dimensioning the pattern separately i could better indicate this.
is it obvious enough to be able to put "10 places" on the drawing and for manufacturing to understand what you mean?
if i have patterns like that, i will usually just create a detail and state that the detail represents however many places for the pattern, like:
detail a
10 places
scale 1:1
(i don't use x (as in 10x) in this particular instance because that doesn't see quite as clear as spelling it out. i will use x for multiples at any other time.)
so far, no vendor has every misinterpreted this method or even questioned it.

matt lorono
cad engineer/ecn analyst
silicon valley, ca
fcsuper,
if you apply the note "10x" to the rectangular pattern or pitch circle in your detail, i would think things would be pretty clear. i have gone 10x 6x ?6.4 on drawings.
if you have an accurate manufacturing process such as machining, you can apply a single positional tolerance to all your holes. if your process is less accurate, you will need a composite tolerance, and you will have to set up your dimensions so that this makes sense.
jhg
drawoh,
when i've done this, the 10x would have to be repeated on multiple dimension. for me, it's quicker and cleaner to just type it in one location to cover the entire detail.
matt lorono
cad engineer/ecn analyst
silicon valley, ca
gmurr, do you use gd&t? if so then where you mention
quote (25 jul 08 10:27):
my real intent is to show that the dimensions within the pattern is more important than the location of the pattern
you may want to consider composite positional tolerancing.
otherwise as others say you basic idea is sound, just make sure you dimension it correctly. i too sometimes spell out places rather than just x like fcsuper for this type of application, however technically you don't need to.
kenat, probably the least qualified checker you'll ever meet...
i've always approached this the way fcsuper recommends.
when the people fear their government, there is tyranny; when the government fears the people, there is liberty.fff"> - thomas jefferson