Corrugated tube
The flexible corrugated (ribbed) plastic tube that connects the pellet bucket to the Hopper. The Vacuum pump creates suction through this tube to lift pellets from the bucket level up to the extruder.
Function
Section titled “Function”- Transports pellets from the bucket to the hopper via vacuum suction
- Flexible enough to route around the machine
- Ribbed design allows bending without collapsing the bore
Critical specifications
Section titled “Critical specifications”| Parameter | Value | Why |
|---|---|---|
| Maximum length | 1.5 m | Longer tubes create a “belly” where pellets get trapped |
| Orientation | Always rising toward the hopper | No dips or U-bends — pellets pool there |
| Seal at hopper | Must be airtight | Even a small leak breaks the suction |
Use the correct tube type
Section titled “Use the correct tube type”The correct tube is a rigid ribbed (corrugated) plastic pipe, 32 mm inner diameter, up to 1.5 m long. The ribs prevent collapse under vacuum and allow pellets to tumble and flow rather than bridging.
If you are using any other tube type (smooth, flexible, garden-hose style), replace it before diagnosing any suction problem.
Tape on tube connections: if the corrugated tube is sealed to fittings with adhesive tape rather than proper clamps, the tape can come unstuck during operation, breaking the airtight seal and stopping suction immediately. Always use clamps or the proper press-fit fittings.
How the feeding tubing is arranged
Section titled “How the feeding tubing is arranged”The pellet feed path uses two different tube types in series, plus a third tube that is not part of the feeding system:
| Tube | Type | Role |
|---|---|---|
| White corrugated tube | Flexible ribbed hose | The moving section: runs up to the extruder and flexes to follow the gantry/extruder motion |
| Grey rigid pipe | Stiff straight pipe (outside the printer) | The static section: connects the white corrugated tube to the pellet source. Being rigid, it holds the bore open and prevents pellets jamming where the line would otherwise sag |
| Separate corrugated tube (cabling) | Flexible ribbed hose | Carries the extruder cabling to Klipper — looks similar but has nothing to do with pellet feeding. Do not confuse it with the pellet tube |
So the standard path is: pellet source → grey rigid pipe (outside the printer) → white corrugated tube (flexes with the extruder) → hopper. Keep the corrugated tube routed so it follows the extruder freely without snagging on the gantry or the cabling tube.
The most common failure point
Section titled “The most common failure point”The joint between the corrugated tube and the hopper is the #1 cause of suction failure across all customer cases. Air leaks here mean the vacuum cannot build enough differential pressure to lift pellets.
Inspect weekly:
- Check that the clamp is tight
- Check that the gasket (rubber seal inside the fitting) is intact and seated correctly
- Compress the gasket slightly by hand — it should feel firm and springy, not flat or cracked
- Replace the gasket if it shows any compression set (permanently flattened)
See Hopper suction problems for the full diagnostic flow.
Routing guidelines
Section titled “Routing guidelines”- Keep the tube as short as possible — 80–100 cm is ideal; never exceed 1.5 m
- Run straight and upward from the bucket to the hopper
- No dips — a low section acts as a trap for flat or small pellets
- Place the bucket close to the machine and raise it slightly off the floor if needed to reduce tube length
Why short and straight matters
Section titled “Why short and straight matters”Pellets are lifted by air velocity, not suction force alone. In a long tube:
- Air can flow past flat or fines-heavy pellets without picking them up
- Recycled and irregular pellets are especially affected
- A “belly” in the tube collects pellets that then fall back
Pellet types and tube performance
Section titled “Pellet types and tube performance”| Pellet type | Performance |
|---|---|
| Uniform 3×4 mm cylinders | Works well even at 1.5 m |
| Flat / irregular (recycled) | Needs short tube + tight seal; add SmoothFlow |
| Small pellets (< 3 mm) | Can partially get past the gasket — check seal tightly |
| Fines / dust mixed in | Vacuum filter fills up faster; clean regularly |
Replacement
Section titled “Replacement”If the tube is kinked, cracked, or permanently deformed, replace it. The tube is standard corrugated pneumatic hose (verify the inner diameter matches the fittings). Available from Ginger support or industrial hose suppliers.
Related notes
Section titled “Related notes”- Hopper suction problems — main troubleshooting guide for the feeding system
- Hopper — the container the tube connects to
- Vacuum pump — the suction source
- SmoothFlow — lubricant that helps transport difficult pellets