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Treating Position Individually as well as in a Pattern

Treating Position Individually as well as in a Pattern

Treating Position Individually as well as in a Pattern

(OP)
Referencing the ASME Y14.5M - 1994, Fig. 5-39 illustrates how to reference the center pin back to the lobes shown in Detail C[2].

In the Front View[2], it is desired to hold features back to these 5 pins independently which is accomplished by identifying each as its own datum.

In Detail B[2], a bushing wants to be located to these 5 pins for a fastener. Can Datum H be treated as individually applied for the pin centers, and as a pattern to locate the bushings?

Thanks for your consideration in this matter.

RE: Treating Position Individually as well as in a Pattern

Well:
What is datum "A" here, a radius?
Are those square cutouts and why cylindrical zones on squares?
What do all the partial circles on the part represent?
What is your thoughts on why G is not primary, here?
What are the lobed things, are the bore with cutouts?
You want to add another datum to the 6X holes to locate the datum "H" holes?
Frank

RE: Treating Position Individually as well as in a Pattern

(OP)
The attached example appears to express what I am trying to convey.
I apologize for the lack of clarity in the example. The example was cobbled from a print eliminating all but the basic details I thought were needed.
Datum A is a diametrical feature of size.
The cylindrical callout on the the position of the squares was an oversight made in haste.
Datum H are five pins (lobed features) which establish location in conjunction with A, which will engage first.
The part has some flexability to it.

The rectangular features are desired to be held individually with each lobed pin referenced, locating it. They can move slightly, individually, each with its own pin.
The bushings, located at the G targets, will have a fastener pass through them when A-H are engaged. While some of them are influenced by the pin near it, the intention is to locate them as a group, rather than individually

Your example suggests that the way is to designate the pin by two datums, one used to refer to the pins as a pattern, and the other to reference each pin individually.

This seems a bit confusing to try to express. The examples in the standard show instances of pattern, and of individually, but not the same pattern being used as both.

In retrospect, the T.O.P|dia0.55(m)|A|H(m)|G is how I'm trying to express rather than stating it as: T.O.P|dia0.55(m)|A|B(m)-C(m)-D(m)-E(m)-F(m)|G

RE: Treating Position Individually as well as in a Pattern

I think it would depend on how you expressed it on the actual drawing. Since it is not right out of the book it will always confuse some. Most of those people are confused by GD&T to begin with! Conceptually, I think it is sound and inevitable if we ever take the concept of functional dimensioning to what I believe to be the logical extension of the intent of the standard. This I wrote in 1990 or so, and I still see it as the end result under the current direction, now.
I left of the "means this" part of the text to make it easier for myself, I just wanted to see if it was what you were looking to do.
Frank

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