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Printing Head

Maintenance and servicing require the manipulation of the head mounted on the Z stage. Listed below are the different workflows and manipulations on the head which a trained operator may need to use.

Deinstallation of the head

Prerequisites

  • Ensure a probe is mounted before starting the procedure to protect the probe the nose holding the probe.
  • The software is closed.
  • Both pressure and system controllers are powered off.
  • The mini-USB was unplugged from the controller.

Process

  1. Rotate the luer lock to unplug the pressure tube.

    Unplug Pressure Tube

  2. Unplug the head cable by pressing the clips on the sides.

  3. Hold the head with one hand and unscrew the two screws with a SW 2.0 screw driver. Note that screw can’t be removed from the head.

    Remove head

  4. Keeping the head in one hand, slightly bend it out and pull it up from its socket. Push the Z stage down can help releasing the head.

Cleaning the sealing screw

Over time, ink can deposit on the printing nose and sealing screw. Keeping the head clean helps to prevent leaks and ensures the performance and reliability of the system.

Prerequisites

  • The head is removed from the Z stage.

Process

  1. Insert a lever or a T1x40 screwdriver into the gripper’s hole and push to open them. Remove the consumable and let the grippers close again. The nose is composed of the parts shown below:

    Nozzleparts

  2. If crystals or particles are present, they need to be cleaned to ensure a proper sealing with consumables. Remove the sealing screw with a T1x40 screw driver.

    Remove sealing screw

  3. If the duct O-ring also need cleaning, remove the duct O-ring from inside the nose piece or the bottom of the sealing screw with tweezers.

    Remove sealing screw

    Remove sealing screw

  4. Proceed to the required steps below to clean the nosepiece, O-rings and the sealing screw:

    1. To remove any water-soluble salts or stains (e.g. copper sulfate crystals from a Cu-based ink), dip the removed parts in deionized water. Suggested standard procedure is 3 min sonication in deionized water.
    2. Isopropanol (IPA) can be used to clean the O-rings and the sealing screw from non water-soluble products. Then, clean with water.
    3. For the nosepiece, wet a cotton swab with deionized water and use it to remove water-soluble products. Use cotton swabs with IPA to remove non water-soluble products. Be careful to not wet or stain the prism during this operation.
    4. Repeat any of those step if needed.
  5. Let all the parts dry for 1-2 hours at ambient conditions.
  6. If the cleaning wasn’t successful, it is advised to change the stained parts (O-ring or screw) for new parts.
  7. Damaged O-rings (deformed, flattened, hardened or cut) should be replaced.

Note

Due to capillarity effects, water can from a droplet inside the nosepiece channel during the cleaning. If the drying time isn’t long enough and the head is reassembled, this water in the pressure channel will degrade or prevent the functionality of the system. A dry cotton swab can be used to remove most of the excess water, but step 6. is mandatory. Apply gentle pressure and pay close attention to not wet or stain the prism.

Prism cleaning

A poor laser signal quality with more than one probe can happen when the prism is dirty. Remove the head and follow the steps below to clean the prism if stains or dirt are noticed:

  1. Wet lint-free cleaning optical grade wipes with a 50/50 % mix of isopropanol (IPA) and ethanol.
  2. Rub the prism surface to remove dust and stains. Don’t apply force as it may scratch the surface.
  3. If marks persist, start again. Depending on IPA quality, white evaporation marks may be left on the prism. In that case, start again.
  4. Let the prism dry for 1-2 hours as IPA may have wet the inside of the nose.

Reassembling the head

After cleaning, assemble the ring and sealing screw in reverse order:

  1. Put the duct O-ring in the nose with tweezers and ensure it rests at the bottom of the hole.
  2. Screw and tighten the sealing screw. To drive the sealing screw correctly, first rotate it anticlockwise until the thread step is passed, then screw it clockwise until the dead stop, without applying extra force:
  3. Put the sealing O-ring on the sealing screw.

  4. Mount a probe on the nose using a lever in the gripper’s hole. Ensure the sealing screw enters the probe reservoir and does not rest on the reservoir’s border.

    Warning

    Make sure no plate is installed in the XY sled as the tip may crash into a plate during the head installation.

  5. Slide down the head to make sure the stud at the back of the head rests in the corresponding socket on the Z stage.

    Reassemble head

  6. Fix both screws with a SW 2.0 screw driver.

  7. Connect the head cable. Both clips click when correctly plugged in.
  8. Connect the pressure tube and rotate the threaded part to tighten the luer lock. Make sure the thinner parts of the lock do not bend.
  9. Plug back in the mini-USB cable at the back of the controller.
  10. Wait 1 min.
  11. Power the pressure controller and system controller on. Wait for about 1 min for all components to boot.
  12. Start the software and let the system initialize itself.
  13. Enter the maintenance mode and perform the following calibration steps as the head and tip may not be in the same position as before due to assembling tolerances:
    • Calibrate XY (Head)
    • Calibrate Z height
    • Top Camera alignment
    • Measure top camera offset

Once the calibration is completed, the system is ready to be used again.