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# I am new to GD&T can someone please explain what all of these mean? Thank you so much2

## I am new to GD&T can someone please explain what all of these mean? Thank you so much

(OP)
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### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

(OP)
What does 1.6 X <-->Y mean in the 3rd image?

### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

1.6 Surface finish applies between points X and Y

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### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

At the top, CTQ means "critical to quality" and it signifies that the given callout (in this case parallelism) is very important -- perhaps for safety or functional reasons. Thus, it is to be verified after production and often this gets into statistical tracking.
The rectangular box next to that CTQ shows the GD&T symbol for parallelism (shown by 2 slashes), which means that the surface on the right side of that picture is to be parallel with respect to datum D (taken from the surface on the left side of that picture). The allowable deviation from perfect parallelism is 0.2 mm over the length of that right-hand surface.

### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

Gambler: Belanger is probably correct when indicating the 0.2 dimension is in mm. However, I don't see anything in your depictions that indicate what the units are for the drawing as a whole (usually found down toward the lower right corner or maybe a bit toward bottom right-center). What it - and any other measurement OTHER THAN the surface finish symbol - means that the numeric value is in the units of the drawing (inches, millimeters, feet, miles, cubits, furlongs, etc.).

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### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

Trailing zeros are not used on metric dimensioned drawings, so that would indicate the dimensions are in inches. However the dimension values would indicate a metric dimensioned part. The drafter needs to update the dimensioning to conform to standards.

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### RE: I am new to GD&T can someone please explain what all of these mean? Thank you so much

It would be interesting to see the tolerance block for the drawing.
First to determine if ASTM Y14.5, DIN 7168, ISO 2768, or house rules apply.

Also because some drawing tolerance blocks set dimension tolerances based on the number of displayed decimal places.
https://community.sw.siemens.com/sfc/servlet.sheph...

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