Bridgeport interact 4 series 2, ATC lock causes z servo to error

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07 Oct 2023 11:50 #282496 by GDTH
Hello,My Bridgeport Interact 4 Series 2 is equipped with a manual ATC. The ATC utilizes a hydraulic booster, which has proven to be quite challenging to work with. However, the booster plays a crucial role in the tool-changing process.Here's how it works: When the ATC is activated, the hydraulic booster triggers a cylinder to lower the tool from the spindle. Simultaneously, another cylinder positioned parallel to the first one inserts a pin into the pulley of the Z-axis, effectively immobilizing it.I am currently using a Mesa 7i80db with a 7i76 controller, using step and dir signals to control the servos.Based on my observations, it seems that the Z-axis moves to the correct position, but the insertion of the pin into the pulley causes a slight displacement. As a result, the servo attempts to return the Z-axis to its intended position, eventually leading to an error.I'm seeking your input on the best approach to address this issue:
  1. Is it possible to deactivate the servo at the end of the ATC? However, this would require rezeroing since LinuxCNC would lose track of the Z-axis position.
  2. Removing the hydraulic pin is an option, but I suspect it serves a vital purpose in the system.
  3. Alternatively, we could deactivate the servo while also providing the Z-axis encoder feedback to the Mesa card, ensuring it maintains awareness of the Z-axis position?
I would greatly appreciate your insights and suggestions.

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09 Oct 2023 15:16 #282616 by Todd Zuercher
There probably is some position point where in that exact position engaging the locking pin would not cause a position displacement. If you can find that position, and set it as the tool change position in Linuxcnc.

If that isn't going to work or isn't possible, could you possibly add encoder feedback to Linuxcnc for the Z-axis? (Such as using the spindle encoder input on the 7i76 if you arn't using it for a spindle encoder.) If you did you could then disable the Z servo drive without loosing position in Linuxcnc.

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15 Dec 2023 18:02 #288246 by hunterlong
I had a similar problem with my BTC1, see my solution in this thread: forum.linuxcnc.org/24-hal-components/479...to-servo-amp?start=0

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