Calibrating E Steps

I revisited Triffid Hunter's calibration page [reprap.org] and tried to tune the extruder steps again.

When I feed the filament without hot end (as instructed) it was feeding about 2-3 mm extra filament, when I fed 100 mm. So, I adjusted the steps per unit for E motor accordingly.

Then I reassembled the extruder, heated up the hot end, and just for the hack of it I fed another 100 mm filamet at a lower speed of 40 mm/min since did not want to jam the hot end (I fed at 100mm/min pace when I did it without hot end).

Now the filament is moved only 86 mm, not 100 mm!!!

I am sure back pressure from the hot end is doing this.. but what I am wondering is.. if this was the feeding rate that I need to use and and calibrate the E steps with, rather than feeding it against no hot end.

The original value of the E steps, which I had in the firmware (which I have downloaded from the vendor of my kit) was 945. After a couple of calibrations the current value I have is 870. So, the initial settings would've pushed the filament more, and I probably would've been closer to 100 mm.

Any ideas?

I've never heard of feeding it without hotend. That doesn't make sense to me. Probably better just to calibrating using the same setup as you will to run it - hotend and everything. It takes me very little time to calibrate:

1.)Wait for it to heat up.
2.)Mark 100mm
3.)Extrude 50mm
4.)Measure again to the mark - call the new measurement "M"
5.)Open your firmware and look at the value of steps. Call this "S"
6.)Cross multiply to find the new value of steps. Call it "x":
M / 50 = S / x
7.)Enter the new value in firmware and upload.
8.)Try again. If still off, cross multiply again.

It usually only takes me 1 or 2 iterations.

no richraps guide on nicer and sclicer and im sure thet the above triffids guide says the same i have the same issue but it does make sense if your gcode says it needs to feed 3mm filament then to print the particular stage that is taken into account i think caluculations the slicer does with your print settings so if if your gcode asked to feed 3mm and its not correct then, but like i said i have the same problem and use the esteps as a starting point mine was 778 but had it to 860 but im now calibrating it down as 86 is extruding too much

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So.... are you seconding what Wissing said... or are you saying something else?

chris33 Wrote:
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> no richraps guide on nicer and sclicer and im sure
> thet the above triffids guide says the same i
> have the same issue but it does make sense if your
> gcode says it needs to feed 3mm filament then to
> print the particular stage that is taken into
> account i think caluculations the slicer does with
> your print settings so if if your gcode asked to
> feed 3mm and its not correct then, but like i said
> i have the same problem and use the esteps as a
> starting point mine was 778 but had it to 860 but
> im now calibrating it down as 86 is extruding too
> much

What in saying is basically because I have a off I can change the e steps on the fly so I use triffid hunters guide and measure 100mm then I made adjustments

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]