Inside Tapers


Tapered surfaces must be properly dimensioned to be produced accurately and checked with standard gages.

Only three of the four dimensions given for each figure on Drawing #30 are necessary to define a taper accurately.

A conical taper may be defined by a suitable combination of the following dimensions and tolerances.

  1. The diameter at one end of the tapered feature.
  2. The length of the tapered feature.
  3. The diameter of a selected cross-sectional plane which may be within or outside of the tapered feature. The position of this plane is shown with a basic dimension.
  4. A dimension locating a cross-sectional plane at which a basic diameter is specified.
  5. The angle of the taper.

If subsequent grinding and plating is necessary, each will affect the dimensions used to limit a taper and its intersecting surfaces and should be considered when dimensioning the component.

Explanation of notes found on Drawing #30:

Note 1, Figure 1: Datum means no tolerance allowed.Note 2, Figure 2: Any three dimensions can be used, but not all four.

A standard sized ball can be used to check an inside taper. The diameter of the ball and the distance from the end to the ball’s surface must be specified, as shown in Figure 4.