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difference between dimensions
- Thread starter holyghost
- Start date
Or , the explanation 
1) is a "regular" dimension, this value is what is to be manufactured, plus or minus the tolerances.
2) is a "helper" dimension, placing the same dimension on multiple places on a drawing is not allowed in engineering standards due to if ( in the old days ) when one sometimes corrected dimensions by eraser and pen on the drawing paper it was difficult to remember all instances. It is allowed to place multiple "helper" dimensions if that clarifies the drawing. ( See attached picture . In this example it does not clarify but is still allowed.)
Reference dimensions does not have tolerances.
3) is an "Absolute" value. It's tolerances are determined but GD&T tolerances displayed somewhere else on the drawing.
Regards,
Tomas
1) is a "regular" dimension, this value is what is to be manufactured, plus or minus the tolerances.
2) is a "helper" dimension, placing the same dimension on multiple places on a drawing is not allowed in engineering standards due to if ( in the old days ) when one sometimes corrected dimensions by eraser and pen on the drawing paper it was difficult to remember all instances. It is allowed to place multiple "helper" dimensions if that clarifies the drawing. ( See attached picture . In this example it does not clarify but is still allowed.)
Reference dimensions does not have tolerances.
3) is an "Absolute" value. It's tolerances are determined but GD&T tolerances displayed somewhere else on the drawing.
Regards,
Tomas
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