Required supplies:
Formlabs:
- Fuse 1 generation IR sensor kit (RP-FS1-IRK-02)
Third-party:
- 2.5 mm hex driver (flat-end)
- 3 mm hex driver (flat-end)
- 6.5 mm slotted screwdriver
- Telescoping mirror
- Non-reactive nitrile gloves
On Fuse 1 generation printers, the infrared (IR) sensor sits on the IR sensor flow body, pointed down at the print bed. If the IR sensor flow body or its seals are damaged, the IR sensor may not be able to measure the temperature of your print or the printer may encounter other errors.
Use this guide to replace the IR sensor flow body on a Fuse 1+ 30W printer. To replace this component on a Fuse 1 printer, see Replacing the Fuse 1 IR sensor flow body.

Required supplies:
Formlabs:
Third-party:
Estimated time: 45–60 minutes
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 IR sensor flow body.
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: Prepare the workspace
Clear a workspace around your printer. Ensure that the workspace is well-ventilated and free of dust.
Step 2: 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:



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 upper cooling shroud
Overview: Remove the upper cooling shroud to access the IR sensor flow body.
Step 1: Remove the IR sensor


Open the access door to the IR sensor panel, located on top of the printer next to the hopper. Lift the IR sensor and disconnect the cable from it. Set the IR sensor aside on a flat surface with the sensor window facing up. Feed the IR sensor’s cable down through the plastic shroud.
Using a 3 mm hex driver, loosen and remove the four 8 mm M4 socket head screws securing the upper cooling shroud to the printer. Newer printers also include four washers. Set the screws and washers (if present) aside. Do not separate the upper cooling shroud from the printer at this time.

Step 3: Disconnect the nitrogen valve cable, nitrogen pressure sensor cable, and cooling fan cable


Disconnect the nitrogen solenoid valve from the cable labeled F1+ Nitro N2 Valve Cable. Disconnect the nitrogen pressure sensor from the cable labeled F1+ Nitro Pressure Sensor Cable. Disconnect the cooling fan from cable C047.
For each, disconnect the cable by opening the tab and pulling the plastic connectors apart. Do not pull on the wires themselves.
Step 4: Disconnect the tubing from the upper cooling shroud


Locate the brass tee fitting on the rear side of the cooling shroud. Push the brass ring down while pulling on the plastic tube to disconnect it.
Locate the brass elbow fitting towards the rear hopper side of the printer. Push the brass ring down while pulling on the plastic tube to disconnect it.
To avoid confusing the tubes, use a permanent marker or piece of tape to label them.
Step 5: Separate the upper cooling shroud from the printer
Gently lift the shroud up and away from the printer. Check that all cables and tubes have been disconnected and nothing is caught or tangled. Remove the shroud from the printer and set it aside.
Removing the original IR sensor flow body
Overview: Disconnect and remove the original IR sensor flow body.
Step 1: Disconnect the duct from the flow body
Using a 6.5 mm slotted screwdriver, loosen but do not remove the ring clamp screw on the side of the flow body. Pull the aluminum duct away from the IR sensor flow body.
Step 2: Remove the IR sensor flow body mounting screws
Using a 2.5 mm hex driver, loosen and remove the four 5 mm M3 socket head screws securing the IR sensor flow body to the printer.

Step 3: Open the print enclosure door
Open the filter cabinet door, then manually open the print enclosure door by pulling the blue release handle. This creates enough space to remove the display assembly.
Step 4: Remove the IR sensor flow body
Look up at the ceiling of the print enclosure. Locate the rubber gasket extending down from the IR sensor flow body. Reach inside the print enclosure with one hand and hold the gasket in place. With your other hand, lift the IR sensor flow body off of the printer. Do not remove the rubber gasket. If it comes loose, reposition it as shown here.

Installing the replacement IR sensor flow body
Overview: Mount, secure, and connect the replacement IR sensor flow body.
Step 1: Mount the IR sensor flow body
Orient the new IR sensor flow body with the IR sensor mount facing up and the hole for the aluminum duct facing right. Position the replacement IR sensor flow body onto the printer but do not secure it.
Step 2: Inspect the IR sensor flow body positioning



Use a telescoping mirror to inspect the aforementioned rubber gasket from inside the print enclosure. Confirm that the edge of the gasket is even and flush against the printer ceiling, as shown.
Tip:
If the gasket flange is not seated properly, use a gloved finger to guide it into place from inside the print enclosure. If it is difficult to reseat, remove the IR sensor flow body, readjust, and try again.
Step 3: Secure the IR sensor flow body
Once the rubber gasket is properly seated, thread one 5 mm M3 socket head screw into each of the four screw holes in the base of the IR sensor flow body. Using a 2.5 mm hex driver, tighten until snug.
Step 4: Recheck the gasket
Use a telescoping mirror to check that the rubber gasket did not shift after securing the replacement IR sensor flow body. If it did, readjust its position.
Step 5: Mount and secure the aluminum duct.
Attach the aluminum duct to the replacement IR sensor flow body, then use a 6.5 mm slotted screwdriver to tighten the ring clamp screw.

Reinstalling the upper cooling shroud
Overview: After replacing the IR sensor flow body, reinstall the upper cooling shroud.
Step 1: Reconnect the upper cooling shroud cables


Reconnect the cooling fan connector to the socket labeled C047. Reconnect the solenoid valve to the cable labeled F1+ Nitro N2 Valve Cable. Reconnect the N2 pressure sensor to the cable labeled F1+ Nitro Pressure Sensor Cable.
Step 2: Route the IR sensor cable
Position the top cooling shroud by holding it from the front edge so that the cables covered by the shroud can still be accessed. Feed the IR sensor’s Ethernet cable back through the cutout in the top shroud.
Step 3: Mount the upper cooling shroud
Lower the upper cooling shroud on the printer, aligning the four screw holes in the shroud with the corresponding screw holes in the printer frame. Ensure the shroud is positioned so that there is a uniform gap around the IR sensor flow body. If there is overlap, the IR sensor will not fit correctly.

Step 4: Secure the upper cooling shroud
Thread one 8 mm M4 socket head screw into each of the screw holes in the upper cooling shroud. Using a 3 mm hex driver, tighten until snug.

Step 5: Route the nitrogen solenoid valve tubing
Tuck the plastic tube connected to the nitrogen solenoid valve under the sheet metal hopper cover as shown.

Step 6: Reconnect the tubing to the upper cooling shroud


Locate the brass tee fitting on the rear side of the cooling shroud. Push the plastic tube firmly into the fitting.
Locate the brass elbow fitting towards the rear hopper side of the printer. Push the plastic tube firmly into the fitting.
After insertion, pull on the tubes gently to ensure they do not come out.
Inspect the IR sensor lens for debris and clean it if necessary. Attach the ethernet cable to the IR sensor, then place the sensor back into its mount.

Reinstalling the top panel
Overview: After installing the new IR sensor flow body, 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:



Using a 2.5 mm hex driver, tighten the screws until snug.
Finalizing the repair
Overview: After installing the replacement IR sensor flow body, 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.