Does the extruder gear spring lose tension over time?
My printer has been having extrusion problems for a while and it the cause appears to be that the extruder gear spring has lost tension. In order for extrusion to be consisten I have to manually push down on the tops side of the extruder arm, increasing the pressure between the extruder arm roller and the filament moving over the extruder gear.
The spring itself looks fine, but I get clicking sounds from the extruder gear and inconsistent filament feeding when I am not pressing down on the extruder arm. It is quite obvious that more pressure is needed
Another possibility could be that the teeth on the extruder gear have worn down and no longer grip the filament properly. But the gear looks OK and it doesn't seem likely that PLA plastic could wear down stainless steel.
And yes, I have checked my hotend several times for clogs or obstructions. The nozzle is clear and the PTFE tube is not warped, burned, or clogged. I have also verified that the alignment between the extruder gear, the filament, and the extruder arm and roller is OK.
My plan to deal with this is to grab each end of the extruder spring with pliers and stretch it a bit to increase it's tension when installed. Hopefully I won't break the spring.
翻譯年糕
Hanyang Leong
2016-04-21 09:56:18
Could it be that your main PTFE feed tube has some debris? Otherwise, can also try loosening slightly the M3 bolt holding the plunger arm?
Birk Binnard
2016-04-21 12:45:55
Yes, I did verify that the long PTE tube was clear of any obstructions. I did 2 things to fix the problem:
1. Lengthen the spring by slightly bending the end coils. Stretching the spring did not do anything to it's length.
2. Replace the M3 screw holdi
ng the compression arm with a spare M3 hand-tighten screw.
I noticed that the compression arm was not being held perfectly parallel to the side of the extruder housing, even with the original M3 screw completely tight. The M3 hand-tighten screw has more surface area to hold the compression arm in place and if keeps the arm in the proper position.
When my current print is finished I am going to add a washer under the screwhead to provide even better holding power. If this works OK I'll post a photo sometime tomorrow.
Birk Binnard
2016-04-22 02:42:06
This is how my extruder setup looks now. The washer helps keep the pressure arm better aligned so the roller makes better contact with the filament.
Also notice the slightly bent spring coil at the left. This increases the effective length of the spring and allows the pressure roller to give the extruder gear a better grip on the filament.
