Cross slide extended travel
The cross slide travel on the as supplied lathe is a little limited. It can swing a 7" diameter workpiece but the cross slide cannot be moved back far enough to cut at the edge of such a work piece. There are two reasons limiting the forward movement. Firstly, the extension that houses the thrust bearing at the front of the carriage is quite short and secondly the leadscrew nut movement is limited by the length of the slot in the carriage. This project was initiated to solve both of these problems. At the same time the standard thrust bearing was replaced by a ball bearing for smoother operation and a longer leadscrew was installed permitting greater movement in the rear wards direction. This modification was very much inspired by a similar modification that was carried out by John Moran (www.gadgetbuilder.com).
The photo above shows the new extension on the front of the carriage . This is 65 mm long and turned from 1.1/2" aluminium. The top face is milled away to allow movement of the cross slide over it..
The photo above shows the new extension on the front of the carriage . This is 65 mm long and turned from 1.1/2" aluminium. The top face is milled away to allow movement of the cross slide over it..
This shows the front of the carriage extension. Note the bored recess for the 608ZZ ball bearing and the M4 socket head bolt at the bottom of the two deep holes. The M4 screws bolt the extension to the carriage. Ignore the four small holes in the front of the piece. These are for a later modification. The bearing is retained in the recess by a small M4 grub screw at the bottom.
This shows the front of the carriage. Approximately 25 mm of cast iron has been milled away in order to extend the length of the slot in the carriage. Note that in milling the material away the crest of the vee at the front of the lathe ways has been exposed.
This photo shows the new longer leadscrew, with the ball bearing. This is 275 mm long. It is machined from 10 mm free cutting steel. The thread is left handed and has a 1 mm pitch. One end is turned down to 8 mm for the bearing. When making the leadscrew an extra length was threaded and this was used to make a tap so that I could then make my own leadscrew nuts. The length for the tap was fluted and case hardened.
The assembly is identical to that shown for the topslide modification for extended range, with the same modified friction arrangement for the graduated collar.
If I were doing this modification again then I would not mill out the carriage slot. Instead I would simply move the leadscrew nut 25 mm further back on the cross slide. This would achieve the same result as extending the slot.
If I were doing this modification again then I would not mill out the carriage slot. Instead I would simply move the leadscrew nut 25 mm further back on the cross slide. This would achieve the same result as extending the slot.
