Longer Z travel through Knee axis control?

[greeder88]

Making a automatic tool changer for a Bridgeport knee mill but having a problem with long reamers and drills. The Z axis is only 5 inches so I want to extend this occasionally by putting a geared servo motor on the knee and tie it to the M100...? tool change sequence.

I want to drop the knee down and then up to take out the backlash and adjust the tool length for the new table height needed for very long drill-chuck & drills.

Anyone know what to put in the Hal and INI files to make this custom M-100? I am taxing my abilities on this one.

This would be axis 5.
I run servos but using steppers on the ATC.

[skullworks]

You might want to define the knee as the "W" axis and just have a "W" move as part of a tool change macro or defined tool change position.

This allows you to use this knee travel when needed in your normal G-code programs not just during tool changes.

[greeder88]

I guess it is as easier than I thought.
Just move down (W-5.0) and set the tool length from there and the program should run fine. Move back (W0.0) before I cut again with shorter cutters.

Here I thought I needed a sophisticated M command.

Good thinking. Thanks