Posted: 4/7/2026 8:22:25 PM EDT
[Last Edit: mvintx][Edited]
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Was doing a very long print last night with PA6CF and while the extruder was pulling in the filament, I noticed the spool was tilted over to one side and the PTFE tubing had been pulled several inches into the AMS HT. I pulled the tubing out and secured it with a zip tie. The filament was at the edge of the spool and being pulled down below other layers of filament. I looked at the drive roller and could see the gear rotating along with the spool. Yes, I had the heat on and “rotate spool” was not selected. Trying to sleep last night while the print was going on, I wondered if the rubber drive roller turning in the opposite direction is causing the problem. Anyone else experienced this? So today I made a spindle out of Delrin that will replace the drive roller. It spins freely since it has no gear to engage the drive motor. Haven’t tried it out yet but I don’t see any reason why it won’t work. Will update as soon as I try it. Pic is of the standard drive roller and the replacement spindle. 
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I have had problems feeding Poly ASA GF through my AMS Pro-mostly because its so brittle and cant handle the tight turns. I have also had several other problems with the AMS with only around 500 hours on it, similar to yours. I use a Creality dryer hooked up to the bypass line on my H2 and took the cover off. It acts the same as yours with free rollers. It solves the problems of the AMS. I am thinking of making a spindle that self centers off the filament roll using really good needle bearings. |
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Originally Posted By RhinelandArms: I have had problems feeding Poly ASA GF through my AMS Pro-mostly because its so brittle and cant handle the tight turns. I have also had several other problems with the AMS with only around 500 hours on it, similar to yours. I use a Creality dryer hooked up to the bypass line on my H2 and took the cover off. It acts the same as yours with free rollers. It solves the problems of the AMS. I am thinking of making a spindle that self centers off the filament roll using really good needle bearings. A much easier solution is just run the Bowden into the HT about 3". It behaves similarly to a reverse Bowden setup (practically speaking that's exactly what it is) as it moves the point load of tension to the end of that Bowden which then has degrees of freedom that make any kind of moment around the Y-axis virtually impossible, eliminating the issue you're experiencing. It's probably why I've also never had a spool come off an underfed spool that rides rim-on-spindle. If there is no torque to twist it off the rollers it's good to go. Now if a rim is jacked up and is getting wedged in a tiny relief gap then we'll that's an issue that's easily solved via a different, but similarly simple method as discussed earlier. |
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Originally Posted By -Obsessed-: A much easier solution is just run the Bowden into the HT about 3". It behaves similarly to a reverse Bowden setup (practically speaking that's exactly what it is) as it moves the point load of tension to the end of that Bowden which then has degrees of freedom that make any kind of moment around the Y-axis virtually impossible, eliminating the issue you're experiencing. It's probably why I've also never had a spool come off an underfed spool that rides rim-on-spindle. If there is no torque to twist it off the rollers it's good to go. Now if a rim is jacked up and is getting wedged in a tiny relief gap then we'll that's an issue that's easily solved via a different, but similarly simple method as discussed earlier. I'm assuming the Bowden is the same as the PTFE? I can visualize what your talking about...the tube moving back and forth as the filament feeds. |
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Originally Posted By mvintx: I'm assuming the Bowden is the same as the PTFE? I can visualize what your talking about...the tube moving back and forth as the filament feeds. Correct. Some of us used reverse Bowden setups to solve other issues as well when printing large spools. On a printer with a direct drive extruder and no Bowden setup, like an mk3s+ or mk4 for example, you have issues with larger spools on faster prints as the extruder moves along Z it can cause a ton of pressure on the hotend as it's having to tug against a 5kg spool. So the solve was ro print a custom piece to sit on top of the hotend that offers a Bowden connection into the hotend, and then you run a Bowden up to a fixed location. That eliminates the tension on the filament and removes all the forces tugging against the gantry and hotend as it relocate the point load to the other end of the Bowden, which is now a fixed location relative to the spool. Zero tugging. |
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