Help with possible retraction problem?

Ive been having alot of trouble lately with getting some good quality prints, and I noticed lately that the filament will actually work its way back out of the hotend when it gets to an area where it retracts alot. This is when my quality is lowest. I have a video of it on YouTube:

[www.youtube.com]

Im using Marlin firmware with Ramps 1.4 and slic3r. I think I have messed with with just about every setting slic3r has for retraction but it doesnt seem to help.

Any ideas whats causing this?

Hello,

Whats the retraction speed and lenght and acceleration that you set?

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Are the teeth on the extruder gears meeting properly,
they should be a snug fit, no free play but not too tight.
Is the filament slipping on the hobbed bolt.
You may get better help if you post this in the section for your machine.
Good luck

Length = 1mm
Speed = 45 (was 30 I just moved it to 45 to see if it would change anything)
Extra length on restart = 1mm (Ive tried 0, .2, .4 ,.6 and now 1 with no change in print quality)
Extruder motor is not skipping, slipping or jumping teeth and the filament is not stripping. Im printing with ABS and Ive tried every temperature between 215-255 without any luck. It seems to print fine in the areas where it doesnt retract. Im almost wondering what it would do if i turned the retraction off....

Your extruder gears are not close enough. I can hear the teeth 'click' when the motor reverses. This causes backlash in your extruder.

Yeah thats the hobbed bolt in the hub of the gear wobbling back and forth, an issue I hadnt noticed, however I dont see how that can make the extruder work itself backwards....Im gonna take a look at the firmware maybe theres something in there amiss...

I found the problem! Turned out the default acceleration settings for Marlin were too high so I changed them to Sprinters default settings. My prints are much better and my filament is returning to its original position when retracting.

Old:
//#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 3200/1.25,700} // default steps per unit for ultimaker
//#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 25} // (mm/sec)
//#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

//#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
//#define DEFAULT_RETRACT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for r retracts

New:
#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 3200/1.25,700} // default steps per unit for ultimaker
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 40} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {5000,5000,50,5000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 1000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 2000 // X, Y, Z and E max acceleration in mm/s^2 for r retracts

Thanks for your help guys, I really appreciate it! Now I can focus on getting the slack out of that gear...

Edited 1 time(s). Last edit at 05/10/2013 10:43PM by Crussell.