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S1 General Troubleshooting Guide

S1 General Troubleshooting Guide

Updated on Mar 10, 2025

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How the S1 Works Overview

The S1 works using a force feedback system. It pushes filament forward constantly as the printer is running. As the 3D printer’s extruder moves, the S1 is able to mimic its movement based on the force feedback it receives through the filament.

⚠️ For this reason, flexible filaments will not work with the current version of the S1. These filaments are not rigid enough to provide proper force feedback. ⚠️

The S1 can also be confused by blockages and catching points in the filament path. This will often lead to the S1 thinking the printer is sitting still and it will go into sleep mode (🔵 blue light). In sleep mode the S1 is disabled and will draw very low energy. It automatically leaves sleep mode when it detects movement in the filament. 

 

Common Problems

Filament Not entering Extruder

Symptom: The S1 starts to load filament but it stops when reaching the extruder and goes into sleep mode (🔵 blue light).

  • Cause: The filament is caught on some sort of obstruction at the inlet of the 3D printer’s extruder. 

 

Defects at Filament Transition

Symptom: Under extrusion, gaps, or other defects causing a weak print at the point of the filament transition.

  • Cause 1: A catching point at the inlet of the printer’s extruder causes the filament to get stuck momentarily, creating a gap in the filament transition. The filament eventually moves past the catching point and continues printing normally. 
  • Cause 2: The S1 may struggle to keep up with the printer’s extruder at extremely high printing flow rates. The S1 has a max filament speed of 40 mm/s (~96 mm3/s volumetric flow rate). 
    • Solution 2: If the S1 is moving slower than designed (40mm/s forward filament speed), contact our technical support here.

 

Bowden Tube to Pops Out

Symptom: The S1 is pushing too hard for the printer causing the bowden tube to pop out of the printer’s print head.

  • Cause: The bowden tube is not secured well enough in the printer. The S1 pre-load force is higher than the bowden tube connection can reliably withstand.
    • Solution: Secure the bowden tube to the printer’s extruder using a better method. This may include an adapter or even glue if possible. 

 

Squeaking Coming from the S1

Symptom: There is a squeaking noise coming from the S1 while running. 

  • Cause 1: This can be from a tight fitting TPU wiper inside the S1 gearbox. This part is necessary to prevent dust from entering the system but can lead to squeaking until it is worn in a bit.
    • Solution 1: Allow the S1 to wear in. A break in process of several prints is normal for the S1.
  • Cause 2: Dust and debris from the filament are clogging up the internals of the S1.

 

Filament Stuck in S1 during Reload

Symptom: The S1 operates normally but once the filament runs out it does not leave the S1, causing the printer’s extruder to skip or grind the filament, resulting in a failed print.

  • Cause 1: The printer’s extruder is not strong enough to pull the filament through the S1 once the S1 is no longer able to push and provide the normal preload force (after the filament is past the S1 gears). 
    • Solution 1: If at all possible, use a dual drive geared extruder on your 3D printer. Most newer 3D printers use this style of extruder. Use common methods like increasing spring tension to increase extruder force.
  • Cause 2: Severe kinks at the end of the filament spool get lodged inside of the S1.
    • Solution 2: Use filament with less severe kinks at the end of the roll. Most popular filament brands (i.e. Polymaker, Sunlu, etc.) will work well with the S1 provided the printer’s extruder is not too weak (see solution 1 above).
  • Cause 3: There is a manufacturing defect in the S1. This is apparent when it is extremely difficult to pull filament through the S1 by hand after it has stopped pushing.

 

TPU Clogged the S1

Symptom: Flexible filament was loaded into the S1 and it clogged up the mechanism.

  • Cause: The S1 was not designed to be used with flexible filaments. Reference the section “How the S1 Works Overview” above for more details.
    • Solution: Use the unloading levers on the front of the machine to back out the filament. You may need to pull the filament at the same time. Flexible filaments should not be used with the S1.

 

S1 is Active but Not Moving

Symptom: The S1 says it is active (🟢 green light) but it is not moving causing the printer’s extruder to skip or grind the filament, resulting in a failed print. Usually happens during higher speed printing.

  • Cause: This is a known bug in older firmware versions on the S1.

 

Red Flashing Light

Symptom: The S1 is not moving and there is a 🔴 red flashing light on the side of the machine that was running. This is a safety mechanism to prevent the S1 from wasting filament if a tube pops out of the 3D printer or the S1 causing the S1 to push filament forward full speed. This safety mode is triggered when the S1 does not have any force feedback after running through 15ft of filament. 

  • Cause 1: The gears in the S1 are slipping and it is not able to push hard enough to create the preload needed to operate. 
  • Cause 2: The printer is extruding extremely fast and the S1 is not able to keep up.
  • Cause 3: There is a known firmware glitch in older S1’s that can cause this to happen.

 

How to get more help

View More Technical Support Guides: Click here

View S1 Maintenance Guides: Click here

Contact Technical Support: Click here to fill out a technical support ticket. Our team will be in contact with you within 48 hours.

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