Originally Posted by
ger21
It's not that simple, for a variety of reasons.
1) How do you mount the toolholders in a rack? They don't have the notch that ATC toolholders have.
2) How would the spindle pick them up. A normal ATC toolholder is tapered, so you have a little room as the spindle drops over the tool. With a straight shank, you have zero clearance, and a few thousandsth of misalignment would cause serious damage. I guess you could grind a chanfer on the shank, to help with this.
3) Those tool holders are big and heavy. If you have ANY runout in your spindle, or in the toolholder, you'll get some serious vibration. We will occasionally get a small wood sliver caught between the flange on our spindle and the HSK tool holder. I'm talking about .002" thick. It'll throw off the balance so much that it'll sound like the machine is going to go bouncing across the room. And the machine is 25ft long, and weighs about 10,000 lbs.
Also, any runout will be magnified by the increased length.
4) How do you get a powered wrench to grap the nut. They use spanner wrenches, so you can't just use a socket or something similar.
With no sensors, you never know if the tool holder is held properly, which could be incredibly dangerous when the spindle starts spinning, and 2 lbs of steel with razor sharp edges comes flying out.
There have been various attempts by companies to make "inexpensive" ATC spindles, or ATC adapters. At the end of the day, they end up being not that inexpensive, and they don't work all that well either.