Engineering 22. GD&T Bonus Tolerance. Bruce Mayer, PE Licensed Electrical & Mechanical Engineer [email protected] Skill-Development Goal. Learn How to Use the GD&T MMC to Avoid Inspection-Rejection of Entirely Functional Parts Use AutoCAD to Construct GD&T Feature Control Frames.
This means that the tolerance is .010 if the hole size is the MMC size, or .497. If the hole is bigger, we get a bonus tolerance equal to the difference between the MMC size and the actual size.
Discover that RI does Not Understand “Bonus” Tolerances
To Avoid Scraping Good Parts, Work with a High precision Machine shop to make a Gage Fixture
Gage Pin Precisely Located at (2, 0.75)
Gage Pin Precisely Machined to Ø0.4965
A bit Less than Lo-Lim on Hole-Size;i.e., at the MMCGage Fixture Design
NOT to scale
Read Carefully §10-17 thru §10-23 in Text Book
REJECTED – Out of Spec
The AMEandBonus Tol.
If a hole, for instance, has the following size and geometric control, and the hole measures .502. It would be incorrect to use a bonus tolerance of .003 (.502 - .499(MMC)) if the hole is not perfectly oriented to the Datums. If the hole is out of perpendicular to datum A by .002, for instance, the bonus that may be used is reduced by that amount. The bonus would be merely .001 and the allowable position tolerance = .016.
Use Line to Extend the 0.625 Dim-Ext_ln up to 1.0 offset
Open Geo Tol Dialog Box
Dimension → Tolerance Menus
Use Dialog Box to Spec Flatness & Back Surface as the DatumGDT Demo - 2