## Measuring male tapers

for many types of tapers the angle of the taper is critical if the tapers is to fit a female taper. A simple test is to test the taper against a female taper. A convenient source of these is a tapered sleeve. If the wide end is too small it is obvious and easy to detect because the male taper will be loose in the female taper. If the narrow end is too small it is not so obvious and an error that is unacceptable can be difficult to detect.

One way of measuring a male taper systematically is as follows.

A sine table is fitted with an end plate. The sine table is set to the angle where, if the taper lies on it and against the end plate. The top surface should be horizontal. This is tested with a DTI.

Of course, the top surface is round. With the usual round probe it is impossible to scan the top surface. There are two ways round this. Firstly the DTI is fitted with a probe that present a flat surface to the taper. Alternatively, with a round probe, the height of the probe is set just belowc the top of the taper.But, instead of scanning from one end of the taper to the other the probe scans across the taper at one end. The reading will go from below the surface up to a maximum and then down. Make a a not of the value at the maximum. The probe is then used to scan the other end of the taper. Again, the maximum is noted. The taper is correct is both maximums are the same.

The reason for the probe being set just below the maximum is to reduce the “disturbance” to the probe as it hits the side of the taper.