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Replacing the Fuse 1 doser assembly

In Fuse 1 generation printers, the doser controls the flow of powder from the hopper into the hopper trough before it is spread by the recoater. A faulty or malfunctioning doser will prevent the printer from printing normally.

Use this guide to replace the doser assembly on a Fuse 1 printer. To replace this component on a Fuse 1+ 30W printer, see Replacing the Fuse 1+ 30W doser assembly.

Required supplies:

Formlabs:

Replacement Fuse 1 doser assembly (RP-FS1-DOSE-01)

Third-party:

2.0 mm hex driver (flat-end)
2.5 mm hex driver (flat-end)
8 mm torque driver rated to at least 1.5 N-m
Compliant vacuum with static dissipative components, such as a Class II, Division 2 vacuum
Vacuum brush tools
Hopper vacuum attachment, to be printed in advance (optional)
Appropriate personal protective equipment (PPE) for handling the powder in the printer
Cyanoacrylate glue
Telescoping magnet wand (optional)

Estimated time: 45–60 minutes, plus time to empty the powder hopper and print the hopper vacuum attachment, if needed

Danger:

Read and follow all safety instructions and warnings in the operator manual. Replacement with incorrect parts can lead to burns, shock, fire, or explosion. Dispose of all parts in accordance with local regulations.

Warning:

Do not perform this procedure if the printer was printing less than six hours prior. Failure to do so may result in serious burns. Allow the print enclosure to cool to room temperature before touching or inspecting any Fuse 1 components.

Preparing the workspace

Overview: Prepare the printer and a dust-free workspace for replacing the doser assembly.

Notice:

Fuse 1 generation printers contain 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: Print the hopper vacuum attachment

If you have access to another 3D printer or your Fuse 1 generation printer can complete a print before servicing, print and post-process the hopper vacuum attachment. The STL file is available here.

Step 2: Prepare the workspace

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

Step 3: Empty the hopper

Insert an empty build chamber. Tap Settings > Calibration > Empty Hopper on the printer’s touchscreen. Follow the on-screen prompt on the Empty Hopper screen to transfer the powder from the hopper to the build chamber. This process may take up to an hour.

Step 4: Clean the hopper and powder troughs

Follow the instructions for cleaning the hopper and cleaning the powder troughs from the support article Cleaning all powder out of a Fuse 1 generation printer. You do not need to clean the other components of the printer to replace the doser assembly.

Step 4: Unplug the printer

Disconnect the power cable 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 top panel

Overview: Remove the top panel to access the interior of the printer.

Step 1: Remove the top panel screws

Using a 2.5 mm hex driver, remove the 26 6 mm M4 countersunk screws securing the top panel to the printer:

Six 6 mm screws on the front end of the buffer-side
12 6 mm screws on top of the printer
Eight 6 mm screws on the hopper-side

Set the screws aside.

Step 2: Remove the top panel

Lift the top panel off of the printer by grabbing the IR sensor door and the rear-most edge. Set the top panel aside.

Removing the hopper-side panel and hopper shell

Overview: Remove paneling on the hopper side of the printer to access the doser assembly.

Step 1: Begin removing the hopper-side panel screws

Using a 2.5 mm hex driver, loosen and remove the two black (circled in red) and one chrome (circled in blue) 8.0 mm M4 button head screws from the back-left of the printer. Take note of the locations of these screws, as the placement of the chrome screws is critical to the printer's electrical grounding. Set the screws aside.

Step 2: Continue removing the hopper-side panel screws

Move to the hopper side of the printer. Using a 2.5 mm hex driver, loosen and remove the 10 M4 countersunk screws holding the hopper-side panel to the printer. Remove the top-most 6.0 mm countersunk screws last to make removing the panel easier. Set the screws aside.

Three 16.0 mm screws, circled in green
Three 12.0 mm screws, circled in blue
Four 6.0 mm screws, circled in red

Step 3: Tilt the hopper-side panel

Allow the panel to tilt away from the printer, allowing access to the interlock switch cables. Do not remove the panel at this time.

Step 4: Disconnect the interlock switch and remove the hopper-side panel

Locate the black and red cables leading to the interlock switch on the inner left-hand side of the panel. The cables are retained by a cable clamp. Unlock the cable clamp and disconnect the cable labeled C033.

Separate the hopper-side panel from the printer, taking care to ensure that none of the cables are caught or tangled. Set the panel down on a flat, clean surface.

Step 5: Remove the inner door handle

Using a 2.0 mm hex driver, loosen and remove the four 10.0 mm M3 black countersunk screws holding the inner door handle to the printer. Remove the door handle and set it and the screws aside.

Step 6: Remove the hopper shell

Grip the sides of the hopper shell. Carefully lift the shell upwards then pull it away from the printer. Set the hopper shell and lide aside.

Removing the hopper

Overview: Remove the hopper to access the doser assembly underneath.

Step 1: Disconnect the cables from the hopper

Locate and disconnect the connectors for the hopper LEDs and two powder sensors.

Step 2: Remove the hopper mounting screws

The hopper is secured to the printer using four 4 mm M3 chrome socket head screws: two on each side towards the bottom of the hopper. Using a 2.5 mm hex driver, loosen and remove the four screws. Set the screws aside.

Step 3: Remove the hopper

Grip the hopper from the sides and lift it straight up towards the top of the printer. Once the bottom gasket has separated from the doser, pull the hopper away from the printer.

Do not remove the hopper by tipping it out and away from the printer. This may damage the gasket and lead to powder leaks.

Set the hopper down on the side opposite the window on a flat, clean surface. Do not set the hopper down on either of the gasketed ends or or the windowed side with the powder sensors, as these components may become damaged.

Removing the original doser assembly

Overview: Disconnect and remove the original doser assembly.

Step 1: Remove the doser assembly mounting screws

The doser assembly is secured to the printer frame by four 8 mm standoff nuts. There is a washer between each standoff nut and the doser assembly. Using an 8 mm nut driver, loosen and remove the standoff nuts. It may be helpful to use a telescoping magnet wand to catch and retrieve the washers; if they fall into the printer, they may be difficult or impossible to retrieve. Set the standoff nuts and washers aside.

Step 2: Separate the doser assembly from the printer

Grab the doser assembly and pull it straight back from the printer. Make sure it does not catch on the nearby insulation or printer frame. Do not fully remove the doser assembly at this time, as it is still connected to the printer by two cables.

Step 3: Disconnect the doser cables

Disconnect the doser motor and encoder cables from the doser assembly.

Step 4: Remove the doser assembly

Fully remove the original doser assembly and aside for disposal.

Installing the replacement doser

Overview: Connect, mount, and secure the new doser assembly.

Step 1: Mount the doser assembly

Align the two locating pins on the back of the doser assembly with the corresponding holes on the doser mounting surface. Slide the doser assembly into place until it sits flush against the printer frame. The flange on the left side of the doser assembly should sit behind and parralel to the adjacent insulation panel.

Step 2: Secure the doser assembly

Thread the washers and standoff nuts into the four screw holes in the doser assembly. Using an 8 mm socket wrench or torque driver, torque each nut to 1.5 N-m in the sequence shown here. Torquing the nuts out of order may lead to powder leaks.

Step 3: Reconnect the doser motor and encoder cables

Connect the doser motor and encoder cables to the new doser assembly.

Calibrating the replacement doser

Overview: After replacing the doser assembly, calibrate its home position.

Step 1: Turn the printer on

Plug the power cable back into the rear panel then turn the printer on.

Step 2: Calibrate the doser

On the touchscreen, tap Settings > Calibration > Doser Calibration. Follow the on-screen. The printer will automatically find the correct home position for the new doser. The process typically takes up to 30 minutes to complete.

If any errors are encountered during calibration, follow any instructions provided on the touchscreen and re-run the calibration if necessary.

Step 3: Unplug the printer

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

Reinstalling the hopper

Overview: After installing and calibrating the new doser assembly, reinstall the hopper.

Step 1: Check and clean the hopper gasket

Check that the bottom gasket of the hopper is free of debris, such as powder or pieces of insulation. Clean the gasket if necessary.

Step 2: Mount the hopper

Grip the hopper from the sides and bring it to the printer. Hold the back of the hopper flush against the insulation panel above the doser, then guide the hopper straight down onto the doser until the screw holes at the base of the hopper align with those in the printer frame. Do not reinstall the hopper by tipping it in and towards the printer. This may damage the gasket or create an uneven seal, leading to powder leaks.

If it is difficult to align the screw holes, firmly press the top of the hopper downward with your hand. Do not place any tools or objects directly on top of the hopper, as they may damage the top gasket.

Step 3: Secure the hopper

Thread one 4 mm M3 chrome socket head screw into each of the four screw holes in the hopper. Using a 2.5 mm hex driver, tighten the screws until snug.

Step 4: Reconnect the hopper cables

Reconnect the hopper LED board cable and the two powder sensor cables.

Reinstalling the hopper shell and hopper-side panel

Overview: After reinstalling the hopper, reinstall the paneling on the hopper side of the printer.

Step 1: Mount and secure the inner door handle

Align the four screw holes in the inner door handle with the corresponding screw holes on the front edge of the hopper side of the printer. Thread one 10.0 mm M3 black countersunk screw into each of the four screw holes, then use a 2.0 mm hex driver to tighten until snug.

Step 2: Mount the hopper shell

Grab the sides of the hopper shell and bring it towards the printer. Align the shell with the hopper body, then slide it down on top of the hopper.

Step 3: Reconnect the interlock switch cable

Align the bottom of the hopper-side panel to the bottom of the printer and allow it to lean against you. Reconnect the interlock switch cable, labeled C033, to its receptacle. Route the cables into the cable clamp with the connector positioned below the clamp. If necessary, tuck the interlock cable slack into the side of the printer’s frame.

Step 4: Begin securing the hopper-side panel

Thread one M4 countersunk screw into each of the 10 screw holes in the hopper-side panel. Using a 2.5 mm hex driver, tighten until snug. For greatest convenience and ease of installation, thread and tighten in the following order:

Four 6.0 mm screws below the hopper, circled in red
Three 16.0 mm screws below the filter door, circled in green
Three 12.0 mm screws above the filter door, circled in blue

Step 5: Continue securing the hopper-side panel

Thread the two black 8.0 mm M4 button head screws into the screw holes circled in red in the image here. Thread the chrome 8.0 mm M4 button head screw into the screw hole circle in blue here. Using a 2.5 mm hex driver, tighten until snug.

Reinstalling the top panel

Overview: After reinstalling the hopper-side paneling, reinstall and secure the top panel.

Step 1: Align the top panel

Lift the top panel and place it on top of the printer. Align the screw holes in the top panel with the corresponding holes in the printer frame.

Step 2: Secure the top panel screws

Thread a 6 mm M4 countersunk screw into each of the 18 marked screw holes in the top panel:

Six 6 mm screws on the front end of the buffer-side
12 6 mm screws on top of the printer
Eight 6 mm screws on the hopper-side

Using a 2.5 mm hex driver, tighten the screws until snug.

Finalizing the repair

Overview: After installing the replacement doser assembly, power on the printer and perform final checks.

Step 1: Power on the printer

Connect the power cable to the printer and the power supply. The printer initializes.

Step 2: Test the repair

Start a print. Monitor the printer to ensure that the print proceeds normally. Contact Formlabs Support or your certified service provider to share the results of the procedure.