Runout relative to a planar datum
Runout relative to a planar datum
(OP)
Since we seem to be having so much fun on the other thread about TIR/runout, let me throw this one out there...
A major company that I work with is floating the idea of allowing GD&T specifications for runout (for now let's just say circular runout) but instead of mentioning a datum axis, as is required per Y14.5, they want to allow a single datum reference of just a flat surface. I of course had to tell them that it's not strictly kosher, but their idea intrigued me.
An everyday example that might help is to think of an old-fashioned pencil sharpener, with the mounting surface attached to a table or on the wall. Imagine that, as you turn the crank, we want to check for runout of the rotating part of the sharpener to determine its relationship to the datum plane formed by the mounting surface.
What are your thoughts? It's not allowed by the current standards, but I suppose it makes sense. Any predictions on whether it will make it into Y14.5 someday?
A major company that I work with is floating the idea of allowing GD&T specifications for runout (for now let's just say circular runout) but instead of mentioning a datum axis, as is required per Y14.5, they want to allow a single datum reference of just a flat surface. I of course had to tell them that it's not strictly kosher, but their idea intrigued me.
An everyday example that might help is to think of an old-fashioned pencil sharpener, with the mounting surface attached to a table or on the wall. Imagine that, as you turn the crank, we want to check for runout of the rotating part of the sharpener to determine its relationship to the datum plane formed by the mounting surface.
What are your thoughts? It's not allowed by the current standards, but I suppose it makes sense. Any predictions on whether it will make it into Y14.5 someday?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems





RE: Runout relative to a planar datum
RE: Runout relative to a planar datum
I generally feel if there is a valid need for something, by design or function, not already covered another way, it is OK. I think Evan said it once, and I felt it was true, we are just trying to describe or uncover how something actually works.
Frank
RE: Runout relative to a planar datum
RE: Runout relative to a planar datum
Essentially, think of the desired control as equivalent to parallelism, along with circularity. Hey, I don't really like it myself, I just said I was intrigued by their idea...
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Runout relative to a planar datum
RE: Runout relative to a planar datum
Jim Sykes, P.Eng, GDTP-S
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