Fortus® Loss of Extrusion
If you searched for Fortus loss of extrusion, not extruding, head not feeding, extruder jammed,
ghost printing, printing air, or clogged tip — this page is the master reference.
It also covers common Fortus® operator messages including Model Filament Blocked at Head, Support Filament Blocked at Head,
Model Filament Broken at Cassette, and Model Liquefier Deadlock.
The goal is to isolate the failure path quickly and restore stable extrusion.
Blocked-at-head
Ghost printing
Liquefier restriction
Feed resistance
Drive engagement
Thermal stability
Platforms
Messages
Root Causes
Fast Isolation
Long Builds
Platform Notes
Repair Strategy
Related Guides
FAQ
Platforms Covered
Applies to Fortus® 360mc, 380mc, 400mc, 450mc, 900mc, and F900.
Behavior varies slightly by configuration, but the primary failure paths for loss of extrusion are consistent across these systems.
Fastest Way to Start
Send your model + the exact operator message text (photo preferred) and tell us whether it happens during
load, purge, or mid-build.
The fastest fix depends on whether the restriction is at the tip/liquefier, the upstream feed path, thermal behavior, or drive engagement.
Operator Messages & Common Searches
Operator messages
- Model Filament Blocked at Head
- Support Filament Blocked at Head
- Model Filament Broken at Cassette
- Model Liquefier Deadlock
Search phrases
- Fortus not extruding / not feeding
- Extruder jammed / tip clogged
- Ghost printing / printing air
- Loss of extrusion mid-build
Primary Root Causes
- Tip / liquefier restriction (wear, contamination, partial obstruction)
- Thermal performance (slow heat-up, drift, inability to hold setpoint)
- Upstream feed resistance (routing drag, tube wear, tight bends, canister feed issues)
- Drive engagement (roller wear, contamination, inconsistent grip under load)
- Material condition (brittleness, deformation, storage-related issues)
Fast Isolation Sequence
Ordered to remove the highest-probability causes first — without guessing.
1) Confirm the symptom
- Hard stop message vs print-quality symptom
- Occurs during load, purge, or mid-build
- Model vs Support (or both)
2) Tip / restriction check
- Inspect tip condition and wear
- Run a controlled purge and observe flow stability
- If flow changes after a tip change, treat as restriction-driven
3) Thermal performance validation
- Confirm the system reaches and holds setpoint
- Slow heat-up or drift increases back pressure
- Abnormal airflow/cooling can destabilize extrusion
4) Feed path resistance
- Inspect routing from canister through tubes to head fitting
- Look for drag points: tube wear, sharp bends, misrouting
- Confirm canister feed is smooth and not binding
5) Drive engagement
- Inspect rollers/feed components for wear/contamination
- Check for slipping under load
- Confirm repeatable engagement during purge and build
6) Cassette-related failures
- Repeated “broken at cassette” often points to upstream resistance
- Inspect brittleness + routing drag together
- Confirm tube condition and bend radius
Key Point
“Replace the head” is not always the right first move. The correct decision depends on isolating whether restriction/resistance is local to the liquefier/tip,
upstream feed path, thermal behavior, or drive engagement.
Loss of Extrusion During Long Builds
If extrusion degrades after hours of printing, the root cause is often progressive: rising restriction, increasing back pressure,
thermal drift, or developing drive slippage under sustained load.
Common “Long Build” Patterns
- Starts fine, then fades: restriction/back pressure increases over time
- Intermittent weak flow: drive slip under load or inconsistent feed resistance
- More common in high chamber conditions: thermal balance and airflow become more sensitive
Fortus Platform Notes
- Fortus 360/380/400/900/F900 share similar head/drive behavior families.
- Fortus 450mc: some sensing/behavior differences exist depending on configuration.
- Behavior varies with firmware and installed options.
Repair Strategy
Not all loss-of-extrusion events require full head or major assembly replacement. Structured isolation can determine whether the issue is limited to a tip/liquefier restriction,
drive components, thermal performance, or upstream feed resistance.
How We Decide the Repair Path
- Which message you get (blocked-at-head vs broken-at-cassette vs deadlock)
- Whether the issue is model, support, or both
- Whether it happens during load, purge, or mid-build
- Whether a tip change changes the symptom immediately
Related Fortus® Troubleshooting Guides
The other two Fortus “big three” failure families:
Motion Faults
Auto Home XYZ failures, Failed Auto Z, limit switch states, enable conditions.
Open Guide
Startup / Boot Failures
No power, UPS-related issues, controller boot problems, reboot loops.
Open Guide
FAQ
What causes Fortus loss of extrusion?
Most commonly: tip/liquefier restriction, thermal instability, feed resistance, drive wear/slip, or material condition issues.
Is “Filament Blocked at Head” always a clogged tip?
No. Tip restriction is common, but upstream feed resistance, thermal issues, and drive wear can also trigger blocked-at-head conditions.
Why does my Fortus ghost print without pausing?
Ghost printing often indicates reduced flow that hasn’t crossed the pause threshold. Progressive restriction, thermal drift, or intermittent drive slippage can cause it.
Does loss of extrusion mean the head must be replaced?
Not always. Isolation can determine whether the issue is tip/thermal/feed/drive before any major replacement decision.
Which models does this apply to?
Fortus 360mc, 380mc, 400mc, 450mc, 900mc, and F900 systems.
What’s the fastest info to send for help?
Model + exact message text (photo preferred) + whether it happens during load, purge, or mid-build + model/support/both.
NEXT 3DP is an independent service provider and is not affiliated with or authorized by Stratasys Ltd.