Of the machine parts produced, many tapped holes are provided on base plates and covers. If the tapped hole layout is not properly designed, troubles such as locating errors and excessive machining time may often result. Therefore, it can be said that the fastener layout design is indicative of the designer's technical levels, and is a design parameter to be reckoned with.

Example 1: Screw hole and tapped hole design on round objects

• As long as there is no concern of causing drawing to be misread, one pitch set of the holes are drawn with actual features and the rest are indicated with a pitch circle and center lines ([Fig. 1]).
• The hole quantity and dimensions are indicated with a leader line, starting with the qty. followed by a hyphen and dimensions ([Fig. 1]).

Example 2: Screw hole design for rectangular cover

• If locations of the intersections can be made clear by dimension indications, the centerlines intersecting the pitch line can be omitted. In this case, the number of the repeats must be clearly shown in the dimension indication ([Fig. 2]).
• a) The end hole is located where the lines of 2 sides intersect. In this case, locating of all the holes can be done all at once making it simple and low cost.
• b) The end hole is located on the arc along the cover outer shape, making it necessary to separately locate the hole and more costly.