I've just upgraded from a Harbor Freight 8x14 to a G4003G. I never had any decent carbide tooling, but I've been looking to buy some for the new lathe. I did have some 1/2" HSS before which I've put in the tool holder and set to the center line, and it looks like there would be enough room to use 5/8" tools, but just barely. I wanted to see what everyone else is using. On a related note, I can't drop the tool holder all the way down without unscrewing the knurled knob so far that the locking nut almost comes off. This doesn't seem normal, like maybe the stud is too short. Does anyone else have that issue?