⌲ Cone taper symbol
Cone taper symbol · Indicadores dimensionales · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Taper 1:10 with major and minor ⌀ specified” states a cone taper symbol requirement.
What controls
Graphic symbol placed before the taper callout to indicate that the surface is conical and in which direction it narrows, so the orientation of the symbol shows which way the diameter decreases. Together with the taper ratio or angle, and at least one diameter with its axial location, it fully defines the cone. Without that reference diameter the cone is not defined: the inclination alone does not say where the cone is.
How to verify
Bluing against a master taper gauge or the mating part and assessing the contact pattern, which is the functional check par excellence for mating tapers. Numerically, measuring two diameters a known distance apart, using gauge balls or precision rollers, or CMM measurement with a cone fit, which returns angle, diameter at a given location and axial position. The surface roughness of the taper is usually specified as well, because it affects contact.
Common mistakes when interpreting it
- Machining the taper in the opposite direction to the one the symbol indicates.
- Defining the cone by the angle alone, without the reference diameter and its axial location.
- Accepting the taper on the measured angle without checking actual contact with the mating part.
How to get it in the workshop / if it comes out of tolerance
It appears on tool taper seats, spindle fits and joints that transmit torque by friction. In these applications the contact is what carries the load, so the real requirement is that the taper bears over its whole surface, not just that the angle comes out right. Check the direction of the symbol: machining a reversed taper is a mistake that is not caught until assembly.
Contact at the small end or at the mouth of the taper: angle error; adjust it before continuing. Correct contact but axial position out: error in the reference diameter. Spotty, irregular contact: a finish or form problem on the taper, not an angle problem. On tool tapers, also check that the seat is clean before blaming the part.
Alternative symbol:▽
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