I dont have the machine you mentioned (the 4015), but I looked at their
G4015Z picture.
The clutch at the left end of the feedscrew should be able to handle
changing under power. If you're unsure, you could always disassemble it to
determine if you would want to.
In a Smithy machine, the clutch is a sliding socket that engages a hex head
to engage the feed.

WB
..............

"Loren Coe" wrote in message
news:KfjEb.422665$ao4.1358065@attbi_s51...

snippage

i have not tried to use the lead screw clutch when the motor is on,
never had the nerve. if that is okay to do, it might make some things
easier.