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Replacing the Form 3 cartridge dispense arm

The resin dispense arm sits at the bottom of the resin cartridge slot at the back of the Form 3. When activated, it presses into the cartridge bite valve to dispense resin. A spring automatically retracts the arm when not in use so that resin is not dispensed inadvertently. An issue with the dispense arm may cause the printer to dispense resin too slowly.

Use this guide to replace the Form 3 cartridge dispense arm.

Required Supplies:

Formlabs:

Cartridge dispense arm

Third-party:

3 mm hex driver
2 mm hex driver
T10 Torx driver
Phillips head driver
Nitrile gloves
Paper towels
Needle nose pliers or tweezers

Estimated time: 20 minutes

Preparing the workspace

Overview: Prepare the Form 3 and a dust-free workspace for replacing the cartridge dispense arm.

Step 1: Remove the build platform

Remove the build platform first to avoid dripping resin into the printer cavity.

Step 2: Remove the resin cartridge

Remove the resin cartridge and close the vent cap to prevent resin from dripping off of the bite valve and into the printer.

Step 3: Remove and store the resin tank

Remove the resin tank, place it in the resin tank case, and cover it with its lid. Set the case and tank aside on a clean, flat surface.

NOTICE:

Wear gloves and hold the resin tank by the tank grips on either side to avoid contamination or damage to the underside of the tank.

Step 4: Prepare the workspace

Clear a workspace around your printer. Ensure that the workspace is well-ventilated and free of dust.

Step 5: Unplug the printer

Disconnect the power cable from the printer before continuing with maintenance. Do not perform maintenance on the printer while it is connected to power. Wait five minutes after disconnecting the printer from power before proceeding.

DANGER:

Performing maintenance on the printer while it is plugged in increases the risk of electric shock. Never remove the back panel of the printer while the printer is plugged in. Never reconnect the printer to power while the back panel is uninstalled.

Removing the rear shell

Overview: Remove the rear shell of the printer to gain access to the resin cartridge slot.

NOTICE:

The Form 3 contains sensitive electronic components. Ground yourself before touching any electronics in the printer by using a grounding strap or touching a grounded piece of metal.

Step 1: Remove the rear shell screws (internal)

Open the printer cover. There is one screw on each side of the Z-tower. Depending on the age of your printer, they may be 2 mm hex screws or T10 Torx screws. Use the appropriate driver to loosen and remove the two screws on the side of the Z-tower.

Step 2: Remove the rear shell screws (external)

Rotate the printer to access the rear. Use a 3 mm hex driver to loosen and remove the two screws on the back of the printer, near the power and data ports.

Step 3: Remove the rear shell

Gently flex the sides of the rear shell outwards to unclip it from the printer frame. Pull the rear shell directly away from the printer to remove it. Set the rear shell aside.

Locate—but do not remove—the two nuts, retained in the lower shell, that previously secured the external rear shell screws. Ensure that they did not come loose while removing the rear shell.

Step 4: Access the cartridge dispense arm

There are two ways to access and replace the cartridge dispense arm: by removing the cartridge floor or by removing the cartridge slot plate above it. The cartridge floor is held in place with two 2 mm hex screws, while the cartridge slot plate is held in place with four 2 mm hex screws. Depending on your machine, one set of screws may be easier to remove than the other.

Test both sets of screws. If any given screw requires excessive force to loosen or feels like it may strip, try the other set. Instructions for both paths are provided below. The photos in the sections for removing and replacing the cartridge dispense arm show the cartridge slot plate removed and the cartridge floor left in place.

Option 1: Removing the cartridge slot plate

Overview: Remove the plate that covers the resin cartridge slot to gain access to the cartridge dispense spring and arm.

Step 1: Remove the cartridge slot plate screws

Use a 2 mm hex driver to loosen and remove the four screws holding the cartridge slot plate to the Z-tower.

Step 2: Remove the cartridge slot plate

Option 2: Removing the cartridge floor

Overview: Remove the cartridge floor to gain access to the cartridge dispense spring and arm.

Step 1: Unscrew the cartridge floor screws

Using the 2 mm hex driver, unscrew the two screws securing the cartridge floor to the printer frame. Set the screws aside.

NOTICE:

The cartridge floor is still attached to the printer via the cartridge spring finger cable. Do not pull on the cable or pull the display assembly away from the printer. Doing so may damage the cartridge spring finger cable.

Removing the cartridge dispense spring

Overview: Clean the cartridge floor and remove the cartridge dispense spring from the printer.

Step 1: Clean the cartridge floor

Absorb any resin on the cartridge floor with a clean paper towel.

NOTICE:

Do not use any solvents to clean the cartridge floor. Any solvent on the cartridge floor can contaminate resin dispensed during subsequent prints.

Step 2: Unscrew the cartridge spring finger assembly screws

Use the 2 mm hex driver to loosen and remove the three screws that secure the cartridge spring finger assembly to the bottom of the cartridge slot.

Move the cartridge spring finger assembly to the side to access the cartridge dispense spring. Do not unplug the cartridge spring finger assembly.

Step 3: Remove the cartridge dispense spring

The cartridge dispense spring is attached to the resin dispense arm and to a metal tab on the cartridge floor. Gently remove the spring from the metal tab using needle nose pliers, tweezers, or another similar tool.

Remove the other end of the spring from the dispense arm. Set the spring aside.

Removing the cartridge dispense arm

Overview: Remove the cartridge dispense spring from the printer.

Step 1: Unscrew the cartridge dispense arm screw

Using a Phillips head driver, unscrew the screw securing the cartridge dispense arm to the cartridge dispense floor. Set the screw aside.

Step 2: Remove the cartridge dispense arm

Gently lift the cartridge dispense arm off its mount. Set the cartridge dispense arm aside.

Installing the new cartridge dispense arm

Overview: After removing the old cartridge dispense arm, install the replacement cartridge dispense arm.

Step 1: Mount the cartridge dispense arm

Align the post on the distal end of the cartridge dispense arm with the curved slot in the cartridge floor. Press the cartridge dispense arm onto its mount.

Step 2: Secure the cartridge dispense arm

Insert the cartridge dispense arm screw into the screw hole in the cartridge dispense arm. Tighten the screw with the Phillips head driver until finger tight.

Reinstalling the cartridge dispense spring

Overview: After replacing the cartridge dispense arm, reinstall the cartridge dispense spring.

Step 1: Install the cartridge dispense spring

Slip the ends of the cartridge dispense spring over the hook on the resin dispense arm and over the metal tab on the cartridge floor using needle nose pliers, tweezers, or another similar tool.

Step 2: Test the cartridge dispense spring

Push the dispense arm to extend the cartridge dispense spring. Release the dispense arm and ensure that the spring fully retracts.

Step 3: Install the cartridge spring finger assembly screws

Place the three 2 mm hex screws into their respective holes in the cartridge spring finger assembly and thread them into the floor of the cartridge slot. Tighten the three screws using the 2 mm hex driver. Do not overtighten to avoid stripping the screw threads.

Option 1: Reinstalling the cartridge slot plate and rear shell

Overview: After installing the replacement cartridge dispense spring, reinstall and secure the cartridge slot plate.

Step 1: Align the cartridge slot plate

Orient the cartridge slot plate vertically, with the cutout at the top. Align the four holes in the cartridge slot plate with the four screw holes in the Z-tower.

Step 2: Install the cartridge slot plate screws

Thread one 2 mm hex screw into each of the four holes. Tighten the screws using a 2 mm hex driver. Do not overtighten to avoid stripping the screw threads.

Option 2: Reinstalling the cartridge floor

Overview: Reinstall the cartridge floor.

Step 1: Mount the cartridge floor

Slide the cartridge floor into the space directly above its mounting points. Lower the cartridge floor into place so that the screw holes in the face of the cartridge floor are aligned with the screw holes in the printer frame.

Step 2: Secure the cartridge floor

Insert the two cartridge floor screws into their respective holes in the cartridge floor. Tighten the screws with the 2 mm hex driver until finger tight. Proceed to reinstall the rear shell.

Reinstalling the rear shell

Overview: After performing any other maintenance procedures, reinstall and secure the rear shell.

Step 1: Replace the rear shell

Place the rear shell back onto the printer. Press it towards the front of the printer to ensure that it fully seats in place. There should be no gaps between the rear shell and the side or bottom shells.

Step 2: Secure the rear shell

Using a 3 mm hex driver, screw the two 3 mm hex screws into the rear of the printer.

Open the printer cover. Using a 2 mm hex driver or a T10 Torx driver (depending on the type of screws in your printer), screw the two Z-tower screws into the sides of the Z-tower.

Finalizing the repair

Overview: After installing the new cartridge dispense arm, power on the printer and perform final checks.

Step 1: Power on the printer

Close the printer cover and connect the power cable to the printer and the power supply. The printer will initialize.

Step 2: Test the printer

Insert a resin cartridge into the printer and check that the printer detects it properly. Insert a resin tank and build platform, then start a print and check that the printer dispenses resin properly.