Grinding Filiment

So I have a working mini kossel 3D printer, however I am running into some issues:

The hopped geared feeding filiment to the hotend is grinding away my filiment sometimes as it is feeding through to the hotend it seems very inconsistant it happens usually at the start of the print or at the end. I have been playing with slicer settings mainly retract speed and length but for some reason nothing is woking. My bed is level and i dont think my motor is skipping any steps. Can anyone shed some light on this type of problem?? I have been taking my retraction speed down but this then leaves unwanted plastic lines between the print.

A smaller issue I have is the nozzel drags over already printed layers with some prints. my question for this problem is what slicer setting can i play with to try and stop this from happening??

Any advice is appriciated!

I had this problem on my Mini Kossel. The problem was that the extruder motor was much more powerful than ot needed to be. When the nozzle was temporarily obstructed, for example because of starting the first layer too low or over extruding, instead of the motor skipping steps, the extruder drive ground through the filament. Reducing the extruder drive motor current from 800mA to 500mA fixed the problem.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks for your help DC,

Is this a slicer setting or is this a change in marlin?
I suspect its a marlin change and I think I found the correct line of code to change but im not sure....From my understanding this line of code controls the PWM's on the stepper motor divers digitally?
#define DIGIPOT_MOTOR_CURRENT {135,135,135,135,135} would i just change the corrisponding extruder motor down to about 500 mA (ie change the fourth value in down to pot size like 100 or 115 or something?

You don't mention what your electronics are, so an exact answer is not possible. If you have RAMPS and Pololu drivers, it is a physical hardware adjustment to the driver cards. If you have a more advanced card/driver combo, it may be supported in software. The only certainty is that this is *NOT* a setting in the slicer . . .

- Tim

Tim thanks i figured so after some more research and thanks, i Use the arduino mega + RAMP 1.4 Kit from think3dprint3d!
My hope is not to have to adjust the setting maually because it would be difficult to tune versus just setting the settings in marlin where i know it would be correct im just looking for the line of code in marlin that sets the power for extruder or motors im not sure if this is it #define DIGIPOT_MOTOR_CURRENT {135,135,135,135,135}

If it's RAMPS 1.4, the only choice is manual on the driver - the circuitry for software control does not exist in RAMPS. It's not really that bad though . . .

- Tim

If i have an attached panel one display that lets me control the RAMPS board directly would i just set the extruder Vmax from 800 to 500?? or does this value mean something else?

Again, *A RAMPS 14 CANNOT SET MOTOR CURRENT! THE NEEDED CIRCUITRY DOES NOT EXIST IN RAMPS!*

Software can show anything - that doesn't mean that the hardware supports it!

- Tim