How to machine large taper thread on ordinary lathe

The use of moving tailstock to process cones is only suitable for workpieces with thimble holes at both ends, so it cannot be used to process inner cone surfaces (the tailstock has nowhere to top the thimble).
Using the adjustment headstock to make the spindle and the bed guide at an angle can easily process the inner and outer cones and conical threads, but the headstock should be restored to normal after adjustment. If the adjustment is not good, it will directly affect the machining accuracy of other workpieces in the future. Besides, the taper of 130mm long, 150mm big end, and 120mm small end seems to be less than adjustable for the headbox of an ordinary lathe.
Generally use profiling processing: install the profiling on the bed, remove the middle carriage screw rod, and connect the middle carriage with the profiling in the appropriate position, and the small carriage is rotated 90 degrees to replace the middle carriage to complete the cutting Movement, adjust the angle between the master and the bed rail, so that when the large carriage moves 130mm, the middle carriage moves 15mm under the limit of the master (ie the required taper). After adjustment, it can be processed as normal As with cylindrical threads, taper or conical threads (including internal and external threads) with the same taper are directly processed, but the feed is carried out with a small carriage, and the middle carriage is restricted by the mold to move the tapered surface.
The advantage of using the master model is that as long as the connection between the middle carriage and the master model is separated after use, and the screw rod is installed back, the lathe can work normally without resetting.