I'd approximate it with a few tangents, 4 or 5 should do it, then blend them with a file.

You could also use a full size filed sheetmetal template clamped to the bed of the lathe as a guide, with a follower "tooth" or stylus on the compound. The cuts are made as you would with X Y movements to do the cuts, but by aligning the tooth to a guide rather than by using the dials to approximate the curve as you mentioned.

Easiest way to make such a template is to print out your section from CAD, check the print is to scale, then use spray glue or glue stick to attach the paper to the sheetmetal. Cut and file the sheetmetal to your printed line. This method can yield very accurate curves.

I'd draw a series of lines on your CAD model at regular intervals and then measure their lengths. You then have a set of co-ordinates to cut to moving the topslide out in equal amounts and the cross slide adjusted to the measured lengths. This will give the profile ias a series of steps that can then be blended, in this case internal are best done with a hand graver and external can be done with files.

This sort of thing

Bit hard to see the 10thou steps on this one

And blended

Edited By JasonB on 16/12/2019 16:28:08

Don't see why it needs to be a curve. A plain taper and final parallel section would work just as well.

Andrew

Thread started at 15:47:45.

“Ok, done. Thanks for the prompt feedback.” That post was made less than 10 1/2 minutes later at 15:58:15!

So, not a difficult solution? Doing it must have been a simple operation.