Setting up for turning a Morse Taper, or similar.
For the viewer who has an involvement in making workshop equipment then turning a precision taper is very likely to be required at some time and, being unable to measure the angles involved, most will adopt a method of trial and error. Having adopted this method myself many times I became aware that it was far from ideal, not least because it required the part to be removed from the lathe to enable it to be tested with its mating half. Because of this I developed the following method.
The Method
Its essential feature is the ability to measure the diameter of the taper at two points a very specific distance apart, from these determining the angle. A test piece is made having two flanges, the distance between their two trailing edges being such that the difference in their diameters must be 0.040” Having made the test piece it can be retained and reused until the flanges have been turned away, so it is particularly quick for subsequent applications..
Even with this method I found that setting the top slide can still be on the difficult side due to the need to make very small adjustments to the angle set, but at least it avoids the turn, remove, test, replace, turn, remove, test, sequence of events. I have though adopted an approach that minimises the problem making the task considerably easier.
Having taken a trial cut leave the tool in contact with the larger diameter and measure
the two diameters. For an example, let us assume the larger diameter is only 0.039”
larger than the smaller, thus needing the angle to increase. Loosen the top slide
and swing it away from the test piece, move the cross slide forward by 0.001 in.
and then rotate the top slide until the tool once again touches the test piece and
re-
Continued on page 2
Workshop Tips
Setting Up to Turn a Precision Taper. Page 1.
Test Pieces for 2 Morse taper and 3 Morse taper and for increasing and decreasing diameters for both sizes.
Test piece in use for an increasing diameter, right to left
