steps per E

[alaris2 1]

can someone explain to me the logic behind steps per E calibration?

my understanding is we are supposed to pull the bowden cable out of the quick release at the extruder and are thus measuring the steps required to make the extruder extrude filament a fixed distance.

this seems to assume that changes due to filament diameter variations, friction in bowden tube, print speed, effects of temperature and friction in the hotend are all nil.

are we saying that marlin or Cura is going to automagically fix this then?

otherwise, shouldn't the procedure be to NOT pull out the bowden cable, but

1) heat the head to intended working temperature

2) extrude some material (to make up for all that which just leaked out during heating)

3) make a mark with a pen on the filament

4) extrude 100mm or whatever

5) measure how far the mark moved

6) maybe do it again to be sure

having just lost yet another print due to Ultimaker Silver thickness variations I can't help thinking changing the filament diameter value in Cura (or any other slicer) is pretty futile since I have no idea what to measure if the filament keeps changing during a print. I've been compensating with M221 S110 and similar as I observe the variations (this print failed because I left it unattended)

[Daid 287]

I think (not 100% sure) Ultimaker will replace your bad silver filament if you contact support.

The whole machine depends on quality filament, if you don't have quality filament you won't get accurate prints.

As for the steps_per_e, the current method is the easiest to do. But you are free to try it with a hot nozzle to see if it makes a difference.

[ian 32]

where do you get your PLA from Daid ? all from fabadashery in england ?

Ian

[Daid 287]

I have 2 good rolls from Ultimaker, red and black. (from before their supplier extruder broke down and the bad rolls of grey arrived)

1 roll of flexible black PLA from Ultimaker.

The rest is all faberdashery.

(And a few scraps I collected, not sure from which sources)

[alaris2 1]

agreed about the quality. this is the replacement silver from UM - I've already sent one back :(

but faberdashery has similar problems - I have rolls from them that vary enough to give problems. the Bertho extruder mod has made a big difference in this regard tho. maybe I get through a lot more filament than others? I've gone through 4.5kg since April.

I get very different values for E depending on which method I use, which is why I was trying to understand the motivation - about 890 for the 'Daid' method, vs. 1400 for the 'destroyer' method.

since the latter matches more closely the machine in a working state, it seems more sensible to adopt surely? or have I totally missed a point somewhere?

[Daid 287]

890 vs 1400? That sounds like the filament or the extruder is slipping somewhere, as cannot imagine you need almost twice as much rotation to get the same amount of extrusion.

[alaris2 1]

no slipping. it's because my bowden tube to hotend interface adds a lot of friction.

as the filament increases in diameter, the friction also increases, but that's another problem.

everything works well at 1400, as long as the filament doesn't exceed 2.95mm or I get a blockage.