While my lathe was slightly dis-assembled I took a couple of pictures of my leadscrew ‘clutch’.
Its very simple, just a shallow ‘top hat’ with three holes in the side attached to the gear banjo (by three countersunk screws) around the end of the leadscrew. Around this is a ring with a threaded hole that the handle fits into, with a peg on the end that can be fitted into the most convenient hole for the chosen gear ratio. Three fiducial marks (I like that word) help with lining the peg up with a hole. Handle is oil blacked to match lathe parts.
The simple nut that keeps the banjo in place is replaced by a belleville washer (dished spring washer) and a longer nut (you can see this poking out in the first picture).. A piece of the gear cover is cut away so the handle pokes out.
Adjustment of the banjo nut needs to be right, but then it can be left alone for ages.
Advantage? You can have fine feed set up all the time, but disengaged, and leave the saddle nut engaged, allowing the leadscrew feed handle to be used. Also no worries about accidentally engaging the leadscrew nuts when the gears are engaged. An best of all, no fiddling round the back with a spanner when you want to engage the gear train.
Neil
P.S. The gear wheel with the chemical metal on it… in my early days I somehow managed to strip the keyway. I bored out the gear, made a little sleeve with a flange and a slot for the keyway. The chemical metal keys to the ribs on the gear and stops the insert rotating.
Edited By Stub Mandrel on 21/11/2011 19:25:55
Edited By Stub Mandrel on 21/11/2011 19:27:47