Orientation & Length
Orientation & Length
(OP)
Morning All
I have a cast part with a defined length and two orientation features, see attached.
The length will be reduced to 189.4 +0.25 -0 how does this affect the two orientation features?
I'm no expert in GD&T!.
Many Thanks
I have a cast part with a defined length and two orientation features, see attached.
The length will be reduced to 189.4 +0.25 -0 how does this affect the two orientation features?
I'm no expert in GD&T!.
Many Thanks





RE: Orientation & Length
Your GD&T looks suspicious to me.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
RE: Orientation & Length
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
RE: Orientation & Length
As drawn, datum A is the centerplace of the 190.60 dimension, not an end face.
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Orientation & Length
Datum feature A if FOS 190.60 itself and sloppy placement of datum feature symbol B doesn't help either.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
It is good practice to select datum features that do not get machined off. I am looking at your datums A and B. Also, it is good practice to separate your casting drawing from your machining drawing. Let the foundry worry about making moulds and melting metal. Make a separate drawing for machining.
As noted by ewf, your datums must be a feature on your part. You cannot attach datums to centrelines.
--
JHG
RE: Orientation & Length
In a way, a datum IS associated with a center line if the datum is established with a diameter. Based on this thread, sounds like you need training and a D&T reference book. I also concur with drawoh that the machined part needs to be shown on a separate drawing with a different part number than the cast part.
Tunalover
RE: Orientation & Length
It is unfortunate use of GD&T (or is it GPS?) that's troubles me.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
My point regarding the center line is that the center line cannot be the datum, only the axis of a datum feature (which is not specified in the example). Y14.5M-1994 ¶4.3.2 states "... shall not be applied to center lines, center planes, or axes...". While I could not find this same statement in the current version, the application requirements are still clearly defined in ¶3.3.2 of the '09 standard.
A good review of the standard should help the OP understand where the example is lacking.
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Orientation & Length
From my understanding and reviewing the examples in the standard how does my latest effort look?
For the curious the drawing IS a machined casting and I do produce a separate casting and machined drawing.
Many Thanks.
RE: Orientation & Length
I'm interested in my understanding of GD&T on this view.
Many Thanks.
RE: Orientation & Length
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Orientation & Length
This case looks more like Two features One axis (see Fig. 4-24, 4-25 in Y14.5-2009 book)
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
"Know the rules well, so you can break them effectively."
-Dalai Lama XIV
RE: Orientation & Length
One may argue that this definition is open to more than one interpretation - well that's exactly the reason I would avoid it alltogether.
"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future
RE: Orientation & Length
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems