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Barrel clog purging procedure

This is the escalation path for a clog that has already survived the quick fix. Each step is more invasive than the last — do not skip ahead.

When you are on the right page

Section titled “When you are on the right page”
  • The screw turns, nothing reaches the nozzle, and nothing is visible at the inlet
  • Manual extrusion at temperature produces nothing
  • Output is contaminated — black specks, degraded smell — after a nozzle change

Before you start

Section titled “Before you start”
  • The barrel is hot and stays hot for most of this. Heat-resistant gloves, and keep hands away from the nozzle and feed throat while the machine is powered
  • Empty the hopper and turn the vacuum off, so nothing new feeds in while you work
  • Have a purging compound to hand if you are going past step 2

Step 1 — Heat soak, then extrude slowly

Section titled “Step 1 — Heat soak, then extrude slowly”
  1. Set the three Multi-Heating Zones to the temperature of the material currently in the barrel, not the one you were about to print
  2. Give it 10–15 minutes so the whole barrel is at temperature, not just the bands
  3. Extrude manually at a low rate from the console

If material starts to move, keep purging at low rate until the output is clean and stop here.

Step 2 — Push it through with purging compound

Section titled “Step 2 — Push it through with purging compound”

If nothing moves, the plug is solid and needs something driven through it.

Full detail: Deep cleaning the barrel. In short:

  1. With the hopper off, feed a purge medium into the throat. Cheapest is a commodity injection-grade polypropylene — not the PP sold as a printing material, which is a premium compound. Purpose-made options are Dyna-Purge F at 160–302°C, or Airtech Dahlpram SP209 for pellet machines
  2. Purge at high flow to push the contamination out mechanically
  3. Continue until the output runs clean

Check the compound’s temperature range against what the machine can reach: the G1 extruder stops at 280°C, so a compound whose range starts above that is useless here. Full comparison: what to purge with.

Step 3 — Pull the screw

Section titled “Step 3 — Pull the screw”

The last resort, and the only step that opens the machine.

Full procedure, including the holding-torque trick that keeps the screw locked to the motor: Removing the screw for deep cleaning.

Two things worth knowing before you start:

  • The extruder must be hot. The screw does not come out of a cold barrel
  • The extruder stays on the carriage. You remove the four screws between the gearbox and E01 and lift the motor, gearbox and screw out through the top. Detaching the whole print head from the gantry is a different job and is not needed here

Afterwards

Section titled “Afterwards”
  1. Purge until the output is uniform — steady colour, no bubbles, no dark inclusions
  2. Return the zones to your normal profile
  3. Reload the material and run a small test print before going back to production

If the clog returns quickly, treat it as a symptom rather than bad luck: the usual cause is the Feeding Zone running too hot for the flow, which Nozzle and barrel clog explains.

Section titled “Related notes”