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Hopper cleaning

The hopper accumulates pellet dust, fines, and color residue over time. Clean it whenever you switch to a new material, after any contamination incident, or before long storage.

When to clean

Section titled “When to clean”
  • Before switching polymer type (e.g., PLA → PETG) — cross-contamination can cause foaming or degradation
  • Before switching to a lighter color — residual colorant from dark pellets will bleed into the new color
  • After printing with masterbatch — liquid colorant coats the interior walls
  • After printing with fiber-reinforced materials — glass or carbon fibers accumulate in the hopper base
  • Before long storage (> 2 weeks without printing)
  • If you see unusual discoloration or contamination in the first layers of a new material

What you need

Section titled “What you need”
  • Dry lint-free cloth or microfiber cloth
  • Small brush (soft bristle, like a pastry brush or parts-cleaning brush)
  • Compressed air can or small compressor (optional but helpful)
  • Isopropyl alcohol (IPA) for stubborn color stains — only for the interior walls, not near sensors

Procedure

Section titled “Procedure”

Step 1 — Empty the hopper

Section titled “Step 1 — Empty the hopper”
  1. Stop any active print
  2. Turn off the vacuum pump (or let it complete its cycle)
  3. Remove the remaining pellets from the hopper:
    • Manually scoop out what you can
    • Tip the printer slightly if needed to reach the corners
    • Use the vacuum pump briefly to pull the last pellets into the suction path

Step 2 — Remove fines and dust

Section titled “Step 2 — Remove fines and dust”
  1. Use the soft brush to sweep dust and fines toward the outlet at the bottom
  2. Use compressed air (short bursts) to dislodge fines from corners and the mesh/filter screen at the bottom
  3. Do NOT blow compressed air directly into the barrel opening — this can push debris into the extruder

Step 3 — Wipe the interior

Section titled “Step 3 — Wipe the interior”
  1. Wipe the hopper interior walls with a dry lint-free cloth
  2. For color stains from dark masterbatch, dampen a corner of the cloth with IPA and wipe the stained area
  3. Let the hopper air-dry completely before adding new pellets (IPA must fully evaporate)

Step 4 — Check the sensor

Section titled “Step 4 — Check the sensor”

The hopper level sensor (small light/photoelectric device inside the hopper) can accumulate dust on its face, causing false “material absent” readings:

  1. Locate the sensor on the hopper wall
  2. Wipe the sensor face gently with a dry cloth — do not use liquids on the sensor
  3. Confirm the sensor indicator light behaves normally when pellets are present

Step 5 — Reload

Section titled “Step 5 — Reload”
  1. Add the new material
  2. Run a short purge before printing to flush any residual material from the barrel (see Material change and purge)

Notes

Section titled “Notes”
  • The hopper filter screen (if fitted) collects fine particles over time — clean it at the same time as the hopper interior
  • After any maintenance, run 2–3 purge lines before the actual print to confirm the new material is fully loaded
  • If cross-contamination is suspected (wrong pellets mixed in), discard any pellets in the bucket that may have mixed and do a full barrel purge
Section titled “Related notes”