09-06-2015, 06:19 AM
Hi aRM,
I think the tailstock quill *should* be locked by the lever 42 rotating the cross-shaft 41 which has an eccentric, forcing the key 15 to bottom in in the groove in the tailstock quill.
The groove in the quill *should* be open-ended at the rear of the barrel, so wind the handle until the feedscrew 17/18 disengages, then the quill will pull forward out of the tailstock body.
Then, examine the key 15 for wear or breakage, see whether the handle will now rotate the cross-shaft - it should do so, raising and lowering key 15.
If it still won't rotate, loosen and if necessary remove the grubscrew 14 - this is accessed from beneath the nose of the tailstock body, directly underneath the cross-shaft. It looks to be in a recess that is half-shown in the last of your pics, at the far left of the pic. This shouldn't really be necessary, although it's possible that the quill has had enough torque applied to shift the cross-shaft and bind up the grubscrew in its slot...
I've seen sheared keys in tailstocks where an excessive cutting load was applied (e.g. a blunt 2" Morse taper drill in very tough materials hanging up and grabbing in an existing bore), this usually jams the tailstock solid, as the remains of the key is rotated out of the slot in the quill... Was the Apprentice doing anything daft before it failed?
A sheared key that hasn't "travelled" will often leave the missing part elsewhere in the slot, so the remains can't contact the quill and lock it - if yours still moves via the handwheel this may be what's happened, luckily the key is just a piece of ordinary keystock!
I hope this makes sense, and helps!
Dave H. (the other one)
I think the tailstock quill *should* be locked by the lever 42 rotating the cross-shaft 41 which has an eccentric, forcing the key 15 to bottom in in the groove in the tailstock quill.
The groove in the quill *should* be open-ended at the rear of the barrel, so wind the handle until the feedscrew 17/18 disengages, then the quill will pull forward out of the tailstock body.
Then, examine the key 15 for wear or breakage, see whether the handle will now rotate the cross-shaft - it should do so, raising and lowering key 15.
If it still won't rotate, loosen and if necessary remove the grubscrew 14 - this is accessed from beneath the nose of the tailstock body, directly underneath the cross-shaft. It looks to be in a recess that is half-shown in the last of your pics, at the far left of the pic. This shouldn't really be necessary, although it's possible that the quill has had enough torque applied to shift the cross-shaft and bind up the grubscrew in its slot...
I've seen sheared keys in tailstocks where an excessive cutting load was applied (e.g. a blunt 2" Morse taper drill in very tough materials hanging up and grabbing in an existing bore), this usually jams the tailstock solid, as the remains of the key is rotated out of the slot in the quill... Was the Apprentice doing anything daft before it failed?
A sheared key that hasn't "travelled" will often leave the missing part elsewhere in the slot, so the remains can't contact the quill and lock it - if yours still moves via the handwheel this may be what's happened, luckily the key is just a piece of ordinary keystock!
I hope this makes sense, and helps!
Dave H. (the other one)
Rules are for the obedience of fools, and the guidance of wise men...
(Douglas Bader)
(Douglas Bader)