holiness of extruder steps when calibrating

Hi guys,

I'm trying to get my regular Mendel printer to work and several calibration tests aren't turning out as it should.

I have the old Adrian geared extruder, gen6 electronics, slicer and pronterface. I have manually measured the extruder steps/mm before installing the hot-end and it is now set at 718 steps. When extruding 10cm of filament without hot-end, the extruder pulls through exactly 10cm, les than 0.5% error on there.

==> nevertheless, my first layer is spread out quite wide and my nozzle digs into the first layer when doing the second. At the third layer it pulls off the previous layer from the bed. Also, when switching from one 'trail' to another, I get drops of molten filament, which are excellent obstacles for the next time the nozzle passes.

My question is: should I look for other parameters like layer height, infill, acceleration or others for the problem, or should I play with the extruder steps first?

I tried to follow the calibration manual on the reprap.org but I can't get the calibration objects right...

What is your pro advice? Thanks a lot, greetings, home core

No expert here, but it sounds like your bed is not level and your retraction is off or not enough.

let the experts chime in.

Hey Thanos,

Thanks for your ideas. My bed is as level as I can get it to be. Also, I tried a calibration object in the center of the bed (only 2 square cm), hence cancelling out the bed level effect. But the results are the same: the nozzle seems to scratch the previous layer just enough to pull everything out of place. What are good parameters for retraction, I must say I have not checked that yet.

Any pro ideas?

Looks more like your steps per mm on the Z axis might not be perfect or the layer height selected conflict with what your rod can really do.

Reduce your extrusion multiplier to 0.9 to start and move up from there.

Is your Z done with one motor or two?
if two, are they in parallel or series?

have you gone through the pictorial guide from the wiki?

Hello guys, thanks for your advice, I will give it a try.

I have a single motor Z drive (classic Mendel design). The Z-steps have been calibrated using the great prusa website calculator so I'm guessing that's fine (8-21 gear ratio, 1/8 microsteps and 1.25pitch gives me 3360 steps). The pictorial guide is superb, I tried it yes and that's why I was thinking acceleration might be it, the calibration object is quite small (only like 2cm² or o) so maybe the PLA simply doesn't get time to cool off, which makes it come loose combined with the high acceleration it seems to have?