Parallelism GD & T and angle connection

[tost]

Hi,
Could you help me interpret the parallelism GD & T. figure is attached.
I have shown my interpretation , I am not sure which one is correct.

 

[ringman]

Parallelism defines a set of parallel planes at the given distance from the specified datum. All points of the controlled surface must lie within the limits of those planes.

 

[tost]

Ringman,
It is true but in both of my cases set of the parallel planes will lie at distance of 0.2. only difference being in first case it is equally offset by 0.1 in both direction In other case 0.2 in one direction.

 

[ringman]

Im not sure that I understand the 2/50 in the fcf. I think you may have a problem there.

Then there is the question is this per Y14.5?

 

[weavedreamer]

Parallelism is a refinement control. In fig. 6-15 the Profile is 0.4 with the additional requirement that within that 0.4 zone, it be parallel with 0.12 - the 0.12 may not violate the 0.4 profile zone.

On a limit dimension, the upper and lower limits set up the zone, the parallelism should be a refinement of those limits.

 

[tost]

Ringman,
I have myself seen this kind of notation for first time may be from ISO.
But let us forget that part consider only 0.2 instead of 0.5/50 than what is your thought

 

[weavedreamer]

Darn. Keep reading these ISO questions with the ASME glasses on.

 

[ringman]

ME too, disregard my comments. Intended for Y14.5

 

[drawoh]

tost,

Your specification 0.2/50 is identical to just specifying 0.2, given that the length is 50.

Both of your interpretations are correct. The total variation from parallel to datum[ ]A must not exceed[ ]0.2. Your two diagrams show a different distance between datum[ ]A and your edge. This would be controlled by a ±[ ]tolerance, or by a profile[ ]FCF.

JHG

 

[CheckerRon]

drawoh: That's how I see it too. The /50 is redundant, but who knows how ISO interprets it?

 

[ctopher]

0.2/50 is the first time I have seen this. Reduce the print or make multiple copies can make it unrecognizable...possibly make it "0.2150".

Also, just curious...not clear to me, is datum A representative of a surface or a centerline?

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)

 

[CheckerRon]

Do we have an emoticon for "tongue-in-cheek"?

CTOPHER: This is the wrong forum for this, but, that's what our default Pro/E Wildfire3 weld symbol pallet does to the numerical values in the symbol. Shrink an E size to a B size, and you need magnification to read it.

 

[ewh]

Off topic
I think a "tongue-in-cheek" emoticon is a great idea... up there with "beating a dead horse"... the one that I really want is "herding cats". I could get a lot of use out of that in work-related email.

When the people fear their government, there is tyranny; when the government fears the people, there is liberty. - [small]Thomas Jefferson [/small]

 

[drawoh]

CheckerRon,

The emoticon for tongue in cheek is -).

Optical surfaces are specified for flatness as a multiple of working wavelength, eg [λ]/4. Sometimes, they call up something like 1[λ]/inch. The parallelism specification would have made sense to me if they had gone perhaps 0.2/25. ASME Y14.5M-1994 is pretty clear than the value in the parallelism[ ]FCF is a linear measurement. Perhaps it is an ISO specification. I see this on drawings.

JHG

 

[tost]

ctopher
Datum A is a plane.

CheckeRon
Also I have attached an example from reliable source which explains this symbology.

Drawoh,
"Your two diagrams show a different distance between datum A and your edge."
I did not get what you intended to say above.
Let me say that I define the Ø50 surface from datum A with a basic dimension 20 than will it be correct if the edge of tilted surface lies within a distance of 20 0.0, -0.2 or 20 +- 0.1 ?

 

[ringman]

Interesting enough. Difficult for me to see an application for it.

If I am seeing it correctly this is like limniting the area for the datum feature and also for the related parallel surface. Strange.

 

[tost]

Drawoh,
When you are answering assume only 0.2 and not 0.2/50

 

[drawoh]

tost,

Parallelism controls the variation in distance between Datum[ ]A and your surface. It does not control the distance itself. The difference between your sketches[ ]a and[ ]b is the distance from datum[ ]A.

I did assume parallelism of 0.2. Your "/50" notation is redundant at best.

JHG