Underdosing describes a disruption to the powder flow during a print. This is usually caused by insufficient powder and may result in print failures.

During normal operation, Fuse Vision monitors the printing plane for debris, fibers, voids, or a deficit of powder. If Fuse Vision determines that not enough powder is deposited after a recoating pass, it will intervene and abort the print with Error 112.

Underdosing may also be a sign of a mechanical error with the printer’s recoater motor. If the printer touchscreen displays the error message Error 94/3, contact Formlabs Support or a certified service provider for additional guidance.

• Prints are repeatedly aborted with Error 112, and accompanied by Fuse Vision failure images of partially-covered previously-sintered layers. These images can be accessed and reviewed by downloading your printer’s history package.
• Each successive print attempt fails sooner than the previous one, still with Error 112.
• Powder leaks out from underneath the hopper-side powder trough and onto the print enclosure floor.
• Printer touchscreen displays the error message Error 94/3

• Insufficient powder
• Powder Dosing Offset needs adjusting
• Powder clumps in the printer hopper
• High humidity (Fuse 1 only)
• Debris catcher clogged (Fuse 1 only)
• Recoater motor error
• Contaminated powder

Add sufficient powder to the printer

If the hopper empties during a print, the print fails. Add sufficient powder and powder credit to the printer before starting a print.

Follow Formlabs recommended workflows

Certain materials clump more than others. This can cause obstructions that result in underdosing. Some materials, like TPU 90A Powder, require stirring to ensure that it flows properly.

When working with these materials, follow Formlabs recommended workflows as outlined in the support articles below:

• Using Nylon 11 CF Powder
• Using TPU 90A Powder
• Using Polypropylene Powder

Monitor humidity levels (Fuse 1)

Monitor humidity levels wherever unsintered powder is stored or used, including around the printer and Fuse Sift. High humidity (e.g., in excess of 50% relative humidity when printing with Nylon 12) can cause powders to clump and obstruct powder flow into the dosing system. Fuse 1+ 30W printers are also affected by humidity, but they have an agitator in the hopper to aid with dosing.

Keep humidity low in the work area. If necessary, install dehumidifiers or other air handling and conditioning units as needed.

Adjust the Powder Dosing Offset (Fuse 1+ 30W)

Formlabs recommends raising the Powder Dosing Offset by 5° to prevent print failures when printing with the following materials:

• Nylon 12 Powder (v3.0 or higher print settings)
• TPU 90A Powder (v2.0 or higher print settings)
• Polypropylene Powder (all Fuse 1+ 30W print settings)

Remove the debris catcher (Fuse 1)

The debris catcher at the base of the printer’s hopper traps any foreign objects that may be in the powder before it flows into the dosing system. Debris accumulates behind the catcher, which can become clogged.

Remove all powder from the hopper and remove the debris catcher if you are experiencing underdosing with a Fuse 1 printer.

Resift your powder

Underdosing issues caused by debris or other contaminants may be resolved by passing the powder through the Fuse Sift.

1. Check the Fuse Sift sifter mesh to ensure that all eight turnbuckles are engaging the brim and that the brim itself isn’t bent or distorted.
2. Check the sifter mesh for holes, tears, or fraying strands.
3. Insert an empty build chamber into the printer and empty the printer hopper. Vacuum the remaining powder out of the hopper and troughs.
4. Resift the powder in the Fuse Sift.
5. Refill the hopper with the freshly sifted powder.

Check the recoater motor assembly

If the previous steps did not fix the underdosing issue, inspect the recoater motor coupler.

3. If underdosing alternates with Error 94/3 (PR_ERROR_MOTOR_MOVE_MISSED_HARDSTOP__RECOATER) or started one or more prints before the error appeared, replace the recoater motor assembly following the repair guide linked above. Fuse 1 generation recoater motor assemblies are available for purchase on the Formlabs Store.

Contact Formlabs Support

If the issue persists despite the actions taken, contact Formlabs Support or a certified service provider and upload diagnostic logs.