04-10-2016, 09:06 AM
I can only comment on the piston type. It doesn't mount the holder exactly the same each time but it also doesn't seem to matter a whole lot, I'm not sure why that would be a problem. Coming to size with HSS, a few tenths isn't out of the question. Rough .020 over, one finish pass .010 over, then to size.
You might see an advantage when you assemble the tool holder to the post, the piston needs a wiggle until it drops in, sometime invisible gremlins prevent it and a puff of air clears it. I'm guessing that a wedge might have a better feel, a more positive action. I don't think it could be any more rigid, but maybe they are.
I have a lantern and a 4-way on a South Bend. The QCTP lives on a Logan but if there's any amount of work to do on the SB the toolpost gets moved over to it. There's that much improvement, even with the piston type.
You might see an advantage when you assemble the tool holder to the post, the piston needs a wiggle until it drops in, sometime invisible gremlins prevent it and a puff of air clears it. I'm guessing that a wedge might have a better feel, a more positive action. I don't think it could be any more rigid, but maybe they are.
I have a lantern and a 4-way on a South Bend. The QCTP lives on a Logan but if there's any amount of work to do on the SB the toolpost gets moved over to it. There's that much improvement, even with the piston type.