too much extrusion - what to modify in configuration.h ?

Sorry for this simple question..
Have assembled a very nice coreXY printer
Had to modify the home- and max- parameters to get the movements right.

First print was okay but the extruder stepper seems to push to much filament.
It is making this clicking noise when the gear-wheel slips..
When i slow down the printing, the clicking gets less.

Don't know what nozzle size is currently mounted. Reduced the size to 0.1mm in Repetier Host. No change.

Should i play with the "89" in

#define DEFAULT_AXIS_STEPS_PER_UNIT   {XYZ_STEPS, XYZ_STEPS, Z_STEPS, 89} //XYZ_STEPS       E 84-95

What other lines might be worth a try ? I am new to Marlin :-/

ideas welcome.
I am tired now and have to shut down. Am dreaming that you light my day when i come back tomorrow :-)

Yes... It is the 89 number you want to change. But.... When you change it, be sure to do an M502 to load the 'default configuration.h setup' and then an M500.

You should be able to measure how much it extrudes when you say extrude 10mm. If it extrudes 15mm, you would want to change the 89 number to 89*10/15 which would be 59.

You also need to set the correct nozzle size in the slicer so it can calculate the correct extrusion, standard size supplied with most printers would be 0.4

Edited 1 time(s). Last edit at 01/16/2017 05:11PM by obewan.

Thank you ! Last time i assembled a printer was some years ago. First time i see a bowden extruder..
Yes, seller confirmed 0.4mm nozzle.
And i actually had to increase the 89 because extrusion of 200mm only lead to 188mm :-/

I guess it is something mechanical. The Extruder lever moves up and down when the gear-wheel rotates.
And the clicking noise does not come from the filament slipping back but the gear-wheel is pushed back :-(
Tried with less tension in the spring (that pushes the lever and increases the pressure onto the filament) and it seems to reduce the slipping of the gear-wheel.

Uploaded a short video: [youtu.be]

In the very beginning you can see (and hear) the gear-wheel clicking/slipping back three times :-/

Ideas welcome :-)

P.S. first i could not load the hot hotend with the filament. Had to unscrew the nozzle and push the filament by hand (pressing the lever on the extruder) by hand through the hotend. Then a 3cm long PTFE tube appeared and i manually inserted the 1.75mm PLA filament into it. Then i could print. Later i extruded backwards to remove the filament and then forward extruding worked. So i guess this little PTFE tube is okay now.