Hello,

I think I have figured out my ATC tool jam problem on the 720.

If the air pressure drops below 95 psi the ATC sometimes fails to load the tool holder, because the drawbar does not fully release. The drawbar air cylinder can only fully press the drawbar down at 97 or more psi. This of course is problematic because the 720 pressure should only be 80 psi according to the manual. This explains why sometimes the ATC moves seem to stop harder than I would expect, the previous owners had the 720 set at 100 psi.

So this leads to the chicken and 2 eggs question? Is it a weak air cylinder, or a jamming drawbar, or both?

I have heard of the spring washer breaking and jamming the stack, with this in mind I would like to remove the drawbar with the spindle on the machine.

If any one has experience pulling the drawbar, I would really appreciate any tricks or traps I might run into. :-)

I guessing there is some preload when reassembled?

Thanks, Bryan

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