Most complicated part of the drawing There is more to it than just the numerical values

Holes Engineering Drawing

Showing that placement should match intent These drawings show bolts holes for mounting a flange onto a plate. When mounting the flange, the position of the holes with respect to each other is very important, or else the flange or part won't fit. It makes sense to dimension the distance between the holes, instead of the distances to the edge.

Geometric Tolerancing

Straightness Datum

Geometric Tolerancing is used Things like Straightness Flatness Circularity Cylindricity to specify the shape of features. Profiles Perpendicularity Parallelism Concentricity And More drawing with a feature control frame. This feature control frame is read as The specified feature must lie perpendicular within a tolerance zone of 0.05 diameter at the maximum material condition, with respect to datum axis C. In other words, this places a limit on the amount of variation in perpendicularity...

The Ansi Y or the ISO standard

Ansi Engineering Drawing

The ANSI standards must be understood to read a drawing. Lets look at a sample drawing 1 1 1 Laboratory for Manufacturing and Productivity 1 Massachusetts Institute of Technology Basic Information Included in a Drawing Projected Views Show as many sides as needed for completeness. Cross Sections A view that is good for showing interior features. Table Lower right corner, with material information, part name, designer etc.

Tolerance Zone Size

Drawing With Positional Tolerancing

This feature control frame specifies the tolerance zone as a circle of diameter .010 at MMC, centered according to the basic dimensions given. The size of the tolerance zone is dependent on the size of the hole. A feature control frame can specify the size of the tolerance zone at MMC, LMC or RFS regardless of feature size . MMC of hole .250 LMC of hole .255 Does this feature meet the true position tolerance Calculate deviations in x and y directions. How does this compare to the basic...

Circular Total Runout

Circular Runout

Runout is specified on cylindrical parts. It is measured by placing a gage on the part, and rotating the part through 360 degrees. The total variation is recorded as the runout. Circular runout is measured at one location. Total Runout is measured along the entire specified surface. Measuring angularity is equivalent to measuring parallelism at an angle. Conventional Coordinate Tolerancing In the conventional tolerancing scheme, a hole center axis can reside anywhere in the square tolerance...