Replacing a Z-Motor and Ball-screw Assembly

Owned by Riley gunn
Oct 25, 2023
7 min read

Tools Required

  • 6mm Allen Wrench or Hex Key

  • 4mm Allen Wrench or Hex Key

  • 3mm Allen Wrench or Hex Key

  • 2.5mm Allen Wrench or Hex Key

  • 19mm Combination Box Wrench (12-point ideally for the closed end)

  • Loctite 243

  • 5mL Syringe with Grease

  • Torque Wrench capable of 40 in-lbs

  • Pantheon ball-nut removal and installation tool

Apply Loctite 243 to all metal-to-metal interfaces.

Removing a Z-motor and Ball-screw Assembly

  1. With the machine powered, move the Z-axis to Z300 using the control screen or the web console.

  1. Power off your HS3 using the main power switch on the back of the machine.

  1. Lift the lid and un-plug the relevant z-axis stepper motor connector located beside it.

  1. Using a 4mm Allen wrench or hex key, loosen and remove the four M5x16 socket head screws holding down the stepper motor.

  1. Using a 2.5mm Allen wrench or hex key, remove eight M4x12 button head screws of the side panel to gain easy access to the ball-nut. If it is on the side where filament enters the machine, be sure to disconnect the filament path from the machine.

  1. Loosen and remove the six M5x20 button head screws holding the ball-nut to the Z-axis plate. The motor and ball-screw assembly should now be completely loose from the rest of the machine.

The motor and ball-screw assembly is captured by the top-plate. DO NOT unscrew the ball-nut off the end of the ball-screw without using the provided tool. Risk of irreparable damage to the ball-nut exists.

  1. Gently lift the assembly vertically upwards until the end of the ball-screw is free from the z-axis plate and gently rest it facing out of the machine’s envelope.

  1. Using the Pantheon ball-nut removal and installation tool, gently unscrew the ball-nut off of the ball-screw and onto the tool. Be sure to align them well.

  1. You may now lift the motor and ball-screw assembly vertically up and out of the top-plate and set to the side.

  2. Re-install the ball-nut onto the ball-screw for safe-keeping.

Installing a Z-motor and Ball-screw Assembly

The start of this procedure assumes the z-motor and ball-screw assembly is completely removed, the side panel is also removed, and the z-axis is at approximately Z300.

  1. Using the Pantheon ball-nut removal and installation tool, gently unscrew the ball-nut off of the ball-screw and onto the tool. Be sure to align them well. It is critical not to lose any of the balls within the ball-nut.

 

  1. Gently lower the motor and ball-screw assembly vertically downward through the hole in the top-plate.

 

  1. Carefully screw on the ball-nut to the end of the ball-screw. Ensure the tool with the ball-nut is well aligned. It is critical to not lose any balls within the ball-nut.

 

  1. Once the ball-nut is on the ball-screw, thread it upwards until it is above the z-axis plate, then lower the end of the ball-screw through the z-axis plate. If the motor is not touching the top plate due to the assembly resting on the ball-nut, thread the ball-nut up more until the motor can be fastened to the top-plate.

 

  1. Align the motor such that the cable and connector of the motor faces the mating connector on the top plate.

  1. Secure the motor using four M5x16 socket head bolts with Loctite 243. Torque to 40 in-lbs.

  1. Thread the ball-nut down to the z-axis plate and install two of the six M5x20 button head screws in the 9 and 3 o-clock positions. Loosen by 1/4 turn after bottoming the screw. Ensure the grease port of the ball-nut is facing inwards towards the bed.

  1. Power on the machine using the main power switch.

  1. Home the machine. If the z-axis travels in the opposite direction as expected (down to home instead of up towards the printhead), then you will need to check which stepper drivers you have in the electrical panel.

    1. If your z-axis does home in the wrong direction (meaning you have outdated stepper drivers), you can simply put an “!” in front of the direction pins in the machine config to reverse the direction of that drive. Contact us at support@pantheondesign.ca if you run into problems with this.

  1. Go to the Machine tab on the web console.

  2. Go to the "Hardware" folder.

  3. Open the "HS3-Manta-M8P-v1.1.cfg" file

  4. Scroll down the [stepper_z] or [stepper_z1]

  5. Modify the "dir_pin" reference to include an exclamation point ! in front of the pin reference. (ex: !PB4 instead of PB4)

  6. Home the machine.

  7. Keep a note of which one is inverted so that we can change it back to normal when you receive the new old stepper driver.

TMC51601-TA is the newer stepper driver, TMC5160A-WA is the older stepper driver.

TMC5160A-TA

TMC5160A-WA

Stepper driver location

  1. When homing is successful, jog the Z-axis to 300mm using the web console with the command:

G1 Z300

  1. Jog the Z-axis to 40mm using the web console with the command:

G1 Z40

  1. Using a 3mm hex key or Allen wrench, soft seat the screws holding the ball-nuts and tighten 1/8 turn.

  2. Jog back down to Z=300 using the command:

G1 Z300

  1. Insert the remaining four screws for each ball-nut and soft-seat them.

  2. Tighten the screws to 40 in-lbs in the star pattern below:

 

  1. Once secured, it is necessary to verify the bed is level with the X and Y axes. To do this:

    1. Place a print bed on the heated bed and ensure there is no debris under the bed, on the bed or on the nozzle. Clean or replace the nozzle if necessary.

    2. Ensure any tools or objects or limbs are not in the possible range of motion of the machine.

  2. A built-in command is used now to check how parallel the print bed is with the X and Y axes. It will probe three points on the bed and report the height back in the console on the web-interface. Probe the points over the kinematic mounts by entering the following command in the Klipper Gcode Console:

  1. The goal is the have the reported value as close to 0 as possible. The target is 0 +/- 0.030mm. To adjust the height, loosen the large M12 nut using a 19mm wrench, then tighten or loosen the ball-point set-screw using a 6mm hex key or Allen wrench. There are 3 points in total.

    1. The pitch of the ball-point set-screws are 1.75mm per turn, so for example, when you run the “_PROBE_KINEMATIC_POINTS" command and the results are all -0.875mm, then you would have to tighten each screw by 1/2 turn to approach 0mm.

    2. Run the “_PROBE_KINEMATIC_POINTS" command as many times as needed.

 

 

  1. Once the bed is level, hold the M12 ball-point set-screw in position with the 6mm hex key and tighten the M12 nut using a 19mm wrench. Run the “_PROBE_KINEMATIC_POINTS" command again to ensure the bed hasn’t shifted during the tightening procedure.

  2. Finally, grease the ball-nuts by inject 0.5ml of grease into each of the Z ball nuts. Try to distribute the grease throughout the length of the ball-screw. A good way to do this is to inject a small amount of grease (0.05mL) every 25-30mm. You can use the offline screen or the web-interface to move the axis up and down.

  1. After lubricating the ball-nuts, be sure to re-install all the side panels.

 

 

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