fractional GD&T

[StephenW]

I have a checker who says if I use fractions on my drawing, my GD&T must also be fractional. I am NOT questioning what the checker is telling me as he is all seeing and all powerful but I am questioning whether I can change my GD&T in the model/drawing to display as fractions?

Remember, the checker is all knowing, omnipotent, and above all other authority so his rule is above question. Can I bend pro/e to me the supreme power's desire?

Sorry for going over the top, but hey that's how we roll here.

Steve

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[rapidoconsultin]

Steve

You have two issues:

1. You are mixing dimensional units, which your checker is correct. Good example would be 1.00 with a GTOL of .010. The units must be the same per ASME y14.5 2009.

2. You are not able to create a fractional GTOL and I found no reference to it under the ASME Y14.5.

My advice would be to change the dimensions that have GTOLS to decimals or remove the GTOLS all together. Many times we use GTOLS to better define a feature or a features location. Typically fractional units are of a courser unit of measure.

Best of luck

Eric


In Reply to

[StephenW]

Thanks to Eric and James.

James brought to my attention that y14.5 doesn't allow for fractional dimensioning except in specific situations where the commodity is know and purchased by fractional sizes, ie pipe, lumber.

My specific requirement is on a weldment. So we are not toy14.5 when we are using fractions on the drawing. Doesn't matter, we just make it up as we go anyway. I'll bring it to the bosses attention that we shouldn't be using fractions on our drawings and at the same time, I'll fake my GD&T to make it fractional so I can get my drawing released. I make my engineer happy because he gets his drawing, the checker will be happy because I did what I was told, I'll be happy because I can show the boss we aren't really following ASME (again)like he says. And my boss will probably use it as ammunition to fire me. Woohoo, everyone wins.

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1. You are mixing dimensional units, which your checker is correct. Good example would be 1.00 with a GTOL of .010. The units must be the same per ASME y14.5 2009.2. You are not able to create a fractional GTOL and I found no reference to it under the ASME Y14.5.My advice would be to change the dimensions that have GTOLS to decimals or remove the GTOLS all together. Many times we use GTOLS to better define a feature or a features location. Typically fractional units are of a courser unit of measure.

****

from ASME Y14.5
------------------------------------------------
1.6 TYPES OF DIMENSIONING
Decimal dimensioning shall be used on drawings
except where certain commercial commodities are
identified by standardized nominal designations,
such as pipe and lumber sizes
-----------------------------------------------
It doesn't seem necessary to apply GD&T to stock sizes.