When using the AMS-HT bypass port with stiff filaments that can’t be driven through the normal feed path, every so often the spool gets cocked and then jams. If the spool were jostled periodically with a 1/4 turn forward, 1/4 turn backwards, this would keep the spool from cocking. Of course the motor would need to be turned off (freewheel) when not jostling.
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I have this issue as well. Doing 7+ hour prints with PA6-CF, very hard and brittle material that needs to be fed through bypass port on AMS-HT. After a while the AMS-HT engages the brake so the little roller at the front stops spinning so the extruder keeps pulling until the spool rubs on top of the roller (not spinning) creating additional friction and probably wear. I’ve had prints continue with no filament coming out of the extruder because the extruder sensor detects filament that’s not actually passing.
I’ve also found that taking out the PTFE tube from the back main port after pressing the release button puts the HT into a mode where it doesn’t engage the brake. I then reinserted the PTFE and the HT continued spinning without engaging the brake. I’ll let it run for the next 6 hours to see if it engages brake at any point.
In any case I have both PTFE tubes permanently connected through a Y-SPLITTER and the bypass is set up as EXT spool on the printer, which SHOULD!!! disable the HT brake. Please fix.
Well… that didn’t take long. The brake engaged with the PTFE tube removed. However, I did turn on the dryer without spinning the spool while it’s printing through the bypass port that’s set up as EXT on the printer. I’ve turned off the dryer and wiggled the filament forward/back so the brake is released, dryer is off. I’ll update if it stops again.
The AMS-HT is freewheeling when filament is getting out of the bypass port when dry while printing is off. I can turn on the dryer with or without the spin while drying function and the brake would engage. I can turn off the dryer, wiggle the fillament to disengage the brake, let it print without drying and no problem. When the dryer starts then the brake engages after a short period of time. Dry while printing is my favourite feature of the AMS-HT considering it’s suitable for high temperature materials and efficient with only 1 spool. It’s not clear why this happens, but I prefer feeding PA6-CF through bypass port straight to the extruder since the automatic feeder just doesn’t seem to feed this hard/brittle material. I can’t imagine this being a difficult fix. Spool is set up as EXT on the printer and while it’s printing I’m turning on the AMS-HT dryer with no material in the main port of AMS-HT. I’d really like to see this fixed so we can dry while printing through the bypass port set up as EXT.