This procedure tells you how to set the C Axis engagement on ST-35/40 NGC lathes. In addition, this procedure will tell you how to inspect damage on the gears.

Important: ST-40/45 Reboot Series machines have a revised spindle head casting design and use the same C-axis engagement offset adjustment method as the ST-15 to ST-30 models. To find out which spindle head casting your machine has, check the ST-Series Machine Version - Identification guide. If your machine has the reboot-style spindle head, where the C-axis is located on top of the spindle, refer to the C-Axis - Engagement Offset - Lathe - NGC instructions to set the C-axis Engagement Offset.

Important : This procedure is applied to the illustrated C-axis assembly.

Remove the enclosure panels in the order shown.

Disconnect the air supply [1] to the actuator block for the C axis.

Install the air regulator and cutoff valve on the actuator air supply hose.

Note: This tool will need to be sourced.

Connect the air supply and set the regulator to 85 PSI.

Insert the Service USB key and go into Service Mode.

Go to the Settings tab

• Set 216 Servo And Hydraulic Shutoff to 5000 sec.

Go to the Parameters > Factory tab 

• Set 4.082 SPINDLE ORIENT OFFSET or 30.085 SPINDLE Spindle Orient Offset (SI Units) to 0
• Set 7.078 C_AXIS TOOL CHANGE OFFSET to 0
• Set 7.140 C_AXIS GRID OFFSET to 0
• Set 7.019 C_AXIS INVIS AXIS to FALSE. This makes the C-axis visible.
  
• Set 7.326 C_AXIS ENABLE SELECTIVE POWER SAVING to Disabled. This enables the C-axis to hold position when engaging the C-axis gear. The parameter will reset to its default value after Cycle Powering the machine.

Note: Make sure the C-axis is NOT engaged and the gear teeth will not touch.

Orient the Spindle:

• Press [Current Commands] go to Devices Tab
• Navigate to Main Spindle Orient
• Press [F2]

Zero Return the C-Axis:

• Press [Zero Return] 
• Press [C]
• Press [Single]

Press [RESET].

 Note: The [RESET] button is used instead of E-stop so that the C-axis stays oriented.

Open the cutoff valve to engage the actuator block.

The C-axis gears must engage correctly. Use an inspection mirror to see the gears engage. Do not move the C-axis disc gear more than a tooth. Turn the C-Axis disc gear until the gears align.

With the C-axis gears fully engaged, set the Spindle Orient Offset:

• Press [DIAGNOSTIC] and go to Parameters Tab, then Factory Tab
• Enter 4.082 or 30.085 and [F1]
• Press [S+F3]Press [Y]

Release the air from the actuator block.

Remove the air regulator and cutoff valve from the air supply tube for the actuator.

Connect the air-supply tube to the actuator block for the C Axis.

Now that the spindle offset is set, press [RESET] and engage the C-axis by pressing [C], then [HANDLE JOG].

The axis should engage smoothly and push the mount out.

If the teeth do not mesh, restart the procedure.

Disengage the C-Axis by pressing the [E-Stop] and [RESET].

Press [RESET] and engage the C-axis by pressing [C], then [HANDLE JOG].

Note: Do not move the C-axis.

With the C-axis at 0 and the gears fully engaged, set the Spindle Orient Offset again.

• Press [DIAGNOSTIC] and go to Parameters Tab, then Factory Tab
• Enter 4.082 or 30.085 and [F1]
• Press [S+F3]Press [Y]

Press [E-Stop] and [RESET]. 

Orient the Spindle by pressing [Current Commands] and go to the Devices Tab. Navigate to Main Spindle Orient and press [F2].

Press [HANDLE JOG] then [DIAGNOSTIC] and navigate to the Axis Tab and to the spindle column.

Note the Actual Position value.

Press [RESET] and press C in the Jog Keys area to engage the C-axis.

Note the new Actual Position value.

If the new Actual Position value is greater than +/-0.035. Redo the C-axis engagement until the value is within spec.

Go to the Settings tab

• Set 216 Servo And Hydraulic Shutoff to 120 sec.

Run the C-axis test program to verify the C-axis engagement is correct.

Download the program here.

Listen for smooth operation and no gear noises during engagement. If any faults occur, restart the procedure. 

Place a magnetic base indicator on the spindle head [1] and rest the indicator tip of the pivot block [2].

Handle Jog the C Axis 360 degrees and look at the indicator.

Find the highest point then adjust the stop block adjustment set screw.

Repeat until the gear runout is 0.0005"

If the gear runout is more than 0.0005", refer to the C Axis - Gear Mesh Contact - Load Adjustment - ST - SL procedure.