[WilliHersch]

This is an improvement to a small Chinese lathe. It motorises the cross slide. This photo shows the back end of the cross slide. The aluminium bracket and armoured cable are for X-Y axis encoders.



Some existing designs add a belt drive to the front of the lathe. This is a back end drive coupled directly to the lead screw. The drive motor has an integrated epicyclic gear box coupled to an electromagnetic clutch driving a spur gear. Two additional spur gears drop the mechanism out of the trajectory of the cross slide.
The 3-D CAD design is shown below. The Perspex cover keeps chips out of the gears.



The feed rate can be adjusted from zero mm per minute to about 10 mm per minute by varying the voltage to the motor which can run both backwards and forwards. Watching the rotation of the cross slide handle gives a feeling for the right speed and it can be measured using the x-axis DRO if necessary. When the clutch is disengaged the handle is used to crank the slide manually. When voltage is applied to the clutch it engages and the motor drives the lead screw. The essential parts of the gear train are shown below.


This photo shows the gearbox, without the chip guard mounted on the lathe.



The mechanical parts cost around £20 with an additional £20 for the electronics. The power feed makes the common tasks of facing and parting so much more satisfying than hand cranking. There is some machining skill required to build this gearbox and it probably took more than 50 hours to complete. It might be a good idea to add micro switch interlocks to stop the slide accidentally running too far forwards or backwards under power.

[daniellyall]

Nices