I've been kicking around the idea of buying a small used CNC lathe recently and have come across a couple that are pretty interesting. 95% of the parts I do are smaller than 6" diameter and 6" long, so a chucker would be great. The other 5% of parts can be up to 12" in diameter, but still no longer than 6". The lathes I am looking at are 6" chuck machines with max turning diameters of around 6.5" because that seems to be what is available right now in my price range(cheap!).

The interesting thing about these for me is that the turrets (mounted in line with the z, face toward spindle) are essentially round with very long tool holders that bolt on radially and add around 3-5" to the distance from the tip of an external turning tool to the centerline of the turret. The picture below should make that a lot clearer.

Attachment 182912

My thought is that I could make a tool holder (and tool) that is significantly shorter, gaining back 2-4" radially and allowing me to turn parts as big as can fit in the chuck. This tool obviously could no longer reach the the spindle centerline, but it wouldn't have to. That creates a problem for using the tool presetter and for programming, but I could always just touch off manually. If the controller has a problem seeing x values that much bigger than 'allowable', then I could touch the tool off with a bar of known length in between the presetter and tool, then offset my x values accordingly.

Does anyone see a problem with this? Obviously the diameter of the part is fixed by what I can hold or machine clearances, but I haven't come up with a reason it couldn't work as long as I'm clearing everything.

Thanks for the help!