BS 4500:2009 pdf free download – Limits and fits – Guidance for system of cone (taper) fits and tolerances for cones from C = 1:3 to 1:500, lengths from 6 mm to 630 mm and diameters up to 500 mm.
6 Basis of the system
6.1 Types of cone tolerance
The following four types of tolerance provide the basis of the cone tolerance system.
a) Cone diameter tolerance (TD), valid for all cone diameters within the cone length (L).
b) Cone angle tolerance (AT), given in angular or linear dimensions (ATU or ATD).
c) Cone form tolerance (TF) (tolerances for the straightness of the generator and for the roundness of the section).
d) Cone section diameter tolerance (TDS), given for the cone diameter in a defined section. It is valid for the cone diameter of this section only.
6.2 Cone diameter tolerance, cone angle tolerance and cone form tolerance
Normal cases will be handled by application of the cone diameter tolerance (TD) only. It includes the two tolerances of the types 6.lb) and 6.lc). This means that the deviations of these two types might, in principle, utilize the whole tolerance space given by the cone diameter tolerance (TD).
In case of stronger requirements, the cone angle tolerance and the cone form tolerance may be reduced within the cone diameter tolerance (T0) by means of supplementary instructions. In this case likewise, no point on the conical surface is permitted to lie outside the limit cones given by TD.
In practice, all types of tolerance generally exist at the same time and, as far as normal cases are concerned, each tolerance may occupy a part of the cone diameter tolerance (T0) only in such a way that no point on the conical surface lies outside the tolerance space. In other words, no point on the conical surface is permitted to lie outside the limit cones.
6.3 Cone section diameter tolerance
If for functional reasons the cone diameter tolerance is required in a defined section, the cone diameter tolerance (TDS) [tolerance type 6.ld)] should be indicated. In this case, it is also necessary to indicate the cone angle tolerance.
If general tolerances for the cone angle are specified, for example in an international document, and if it is referred to this tolerance, it is not necessary to indicate special cone angle tolerances.
7 Cone diameter tolerance (TD)
In general, the choice of the cone diameter tolerance (TD) is based on the large cone diameter (D). It is selected from the IT tolerances and applies over the whole of the cone length (L).
If it is not necessary to indicate smaller tolerances of angle and form, a cone diameter tolerance (TD), given on the drawing, applies also to the angle and form deviations. However, in this case all workpieces that conform to Figure 12 and Figure 22 should be accepted.
The symbols of the geometric tolerance system should be used to indicate the cone diameter tolerances referred to the corresponding cone diameter. If the conical surface of the conical workpiece is not intended for a cone fit, the tolerance positions i and j5 should be chosen for preference, for example.