Review on HHIP 3900 1629 Expanding Collet 0.750 - 1.437 by Carlos Reyes

Range is listed as .250-.468 but center hole for expansion screw is .207. So reducing it to .250 leaves a wall thickness of about .0215, so I doubt you can reduce it that much since the cutter will hit the grooves. Maybe a better machinist than me, which doesn't say much. So it doesn't work for me and I haven't tried it, so the three stars are just trying to be neutral. This might work well for a through hole closer to 0.5.