Bushing for stepped collets of lathe MN-80

t is described in detail and shown how the adapter sleeve for the collets of stepped herringbones is made, which expand the capabilities of the MN-80 lathe. The bushing is made on the same MN-80 machine.
In addition to this bushing, it is necessary to make another bushing, which is needed to attract the herringbone collets to the made adapter bushing using a standard cleaning rod. The production of such a sleeve is shown here:
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The sleeve is machined from a piece of bronze. First, the sleeve is machined on one side, a metric taper 1:20, a locating taper is made. It will fit into the tapered bore of the spindle. To grind the cone, it was necessary to turn the upper part of the support by 1 ° 25´ 56 ", that is, with an accuracy of seconds. And for such machines, the counting scale has a division of 1 °.
There is a known method of setting the angle with running-in on the indicator according to the available sample. But I do not have such a sample of a metric cone. But there is a metric tapered hole in the spindle, into which this bushing will be inserted.
In my opinion, setting an angle with a running-in indicator of an existing tapered hole gives a better result than running along a different taper. Even more accurate than the taper in the spindle. The main thing is that there is the best match between the existing taper in the spindle and the taper that will be sharpened.
The fit of the cone was checked by the paint. Good fit, uniform along the entire length.
For further processing of the bushing, I turned it over and fixed it not in the lathe chuck, but inserted it with the conical part into the spindle, where it will stand when working with stepped herringbone collets, that is, in its workplace. I center, drill, reamer, grind the working cone. This installation of the sleeve without the use of a lathe chuck has the following advantages.
Firstly, the minimum runout relative to the axis of rotation of the spindle of all machined surfaces is automatically ensured, and most importantly, the working cone, along which the collets are centered and installed.
Secondly, the rigidity of fastening the part increases by eliminating the lathe chuck and reducing the overhang of the part, that is, its console.
This is not the first time I have used this technique of installing a part for processing it in the same place where it will stand during operation. For example, when processing an adapter sleeve for bell collets, I processed the working cone by installing the sleeve not on its working place, that is, on the spindle, which ensured the minimum runout of the working cone. The video is on my channel:
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I used this technique in the manufacture of a sharpening machine. When turning the seating surfaces for abrasive wheels, the adapters were rotated by the electric motor itself, on the shaft of which they were screwed, and not by a lathe. And the electric motor itself was fixed on the machine bed using a plaster bed. The video is on my channel:
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