Calculating tapers

Bruno - one more thing to remember: I believe it is United States practice to measure the angle as "included angle", whereas the European practice defines the angle as measured from the centerline of turned parts. Thus, if you use one formula and live in a different geographic region, you might have an error of 100 percent. I've been there! Dave

Well, you could always mount a known good part and set up your compound with a dial gage or even feeler gauges. Then all you have to do is remove it, set up your stock and go.

Bruno wrote: Now if I

On manual lathes that lack a taper attachment I use the following procedure to accurately set the angle of the compound rest. First I chuck up a good straight bar. Verify it is running true. Roughly set your angle on the compound rest. Mount a dial indicator on the tool post with the indicator tip resting on the bar. Move the compound rest by stroking it an inch or two and then checking the deflection on the indicator. Remember, the stroke of the compound is the hypotenuse.

Not if the angle is critical. There are too many variables to set angles by that method, cutting tool height amongst them. One uses a sine plate or sine bar and inspects the angle being produced and makes the necessary adjustments to correct the inherent errors made in setup. .

Harold

" Now if I could just figure out how to scale my compound to nail that angle."

I just went thru that with an old live center that the former owner had tried to turn down to the next morse size lower. I finished the OD by calculating what the major & minor diameters would be over the total length of the piece, roughed the od in on the lathe & finished by grinding between centers on the surface grinder. Very easy to tweek angle between centers with the proper setup. While doing that job, I realized for the first time that all the different sizes of morse taper are not of consistant angles. This is also true of jakobs& jarno. Learn something new everyday.