Having trouble calibrating extruder steps per mm  

Re: Having trouble calibrating extruder steps per mm

what happens if you do three successive tests without changing anything? do you get the same length each time?

Joan

Re: Having trouble calibrating extruder steps per mm

To the best of my measuring abilities I get these results after the G1 E100 F100 command, @ the default E280
25.4mm
26.3mm
25.8mm

Re: Having trouble calibrating extruder steps per mm

Hate to be a pain, but there's a reason Prusa and Bondtech don't recommend modifying the default values.

Calibration is there to resolve an unknown variable - typically gear radius. With a bondtech gear system, the variables are very well defined. It's likely that there is a lot more slop in your measurements, due to measurement technique and the variables that shouldn't, or can't be calibrated by E-steps (filament rigidity, idler door tightness, filament diameter).

Basically, if you calculate a value within a few percent of the 280 default steps, then you're probably just looking at noise and should stick with the default, and if you calculate a value that's very different then you've likely made a mistake.

There's also good practical reasons for staying with the default. Prusa print hundreds of parts with stock Mk3s. Combined with their profiles, this makes it easy for others to adapt their .stl files, and release them, knowing that others can print the exact same file, even to pretty tight tolerances. If you have modified your printer (especially if you've got it a bit wrong), then you'll have a lot of problems printing updates and other parts that stick to the Prusa design tolerances.

Re: Having trouble calibrating extruder steps per mm

To the best of my measuring abilities I get these results after the G1 E100 F100 command, @ the default E280
25.4mm
26.3mm
25.8mm

How have you managed to feed 25 mm filaments with a command that should normally feed 100 mm?
Have you made any other changes that may have caused this error?

Re: Having trouble calibrating extruder steps per mm

Hate to be a pain, but there's a reason Prusa and Bondtech don't recommend modifying the default values.

Calibration is there to resolve an unknown variable - typically gear radius. With a bondtech gear system, the variables are very well defined. It's likely that there is a lot more slop in your measurements, due to measurement technique and the variables that shouldn't, or can't be calibrated by E-steps (filament rigidity, idler door tightness, filament diameter).

Basically, if you calculate a value within a few percent of the 280 default steps, then you're probably just looking at noise and should stick with the default, and if you calculate a value that's very different then you've likely made a mistake.

There's also good practical reasons for staying with the default. Prusa print hundreds of parts with stock Mk3s. Combined with their profiles, this makes it easy for others to adapt their .stl files, and release them, knowing that others can print the exact same file, even to pretty tight tolerances. If you have modified your printer (especially if you've got it a bit wrong), then you'll have a lot of problems printing updates and other parts that stick to the Prusa design tolerances.

Fair enough. I've left it at default and just decided to tinker with extrusion multiplier in slic3r

To the best of my measuring abilities I get these results after the G1 E100 F100 command, @ the default E280
25.4mm
26.3mm
25.8mm

How have you managed to feed 25 mm filaments with a command that should normally feed 100 mm?
Have you made any other changes that may have caused this error?

Sorry, I meant that those are the measurements of the filament left after measuring 120 and extruding 100 (20mm being the expected result)

Speaking of changing the extrusion multiplier. Would I need to change any other settings along with it? Changing it from 1 to 1.05 fixed the gaps I was getting in my test print walls. But now he walls are thicker than they should be. Guessing the layer heigh would have to change?

Re: Having trouble calibrating extruder steps per mm

maybe you forgot to desable this code in your startscript?

Re: Having trouble calibrating extruder steps per mm

maybe you forgot to desable this code in your startscript?
2019-01-23 13_29_25-Window.jpg

Is it recommended to remove that? Do most Prusa users remove it?
I would have figured it was there for a reason, ha.

Re: Having trouble calibrating extruder steps per mm

It is there for a reason. It's there because there's a discrepancy in how Slic3r calculates volumes. I can't remember the post, but it's around.

However, I haven't investigated to see how that gcode interracts with the extrusion multiplier. I suspect they are compatible – The extrusion multiplier would be applied directly in the Gcode on a line by line basis, then flow rate is applied either at the printer or through that gcode.

Re: Having trouble calibrating extruder steps per mm

Hi Patrick,
I was able to reproduce the issue.
I solved it by switching the printer off and reboot after save the new value via m500 to the eeprom.

I don't know why this works, but hey, it works. Try it.

Re: Having trouble calibrating extruder steps per mm

Hi Patrick,
I was able to reproduce the issue.
I solved it by switching the printer off and reboot after save the new value via m500 to the eeprom.

I don't know why this works, but hey, it works. Try it.

I believe I tried a hard a hard reset after m500 maybe 2 out of the 10 times I did the test :D.
I'll give it another try though.

Actually now that I think about it, when I sent the M83 and G1 E100 F100 code after the reboot, the extruder made a loud hard violent grinding sound for about 1 second and extruded a few mm 😲. That can't be good.
But then worked normally again when sent the command again.

Edit: oh wow I googled it and this is the exact issue this guys having https://shop.prusa3d.com/forum/prusa-i3-kit-archive--f84/extruder-estep-calibration-t5648.html

Re: Having trouble calibrating extruder steps per mm

hahaha jap, same here. after reboot my first commands was also

M83
G1 E100 F100

and it spinns the hole 100 in a realy realy shocking second.
Holy macaroni! it took some time till i found out it is just the first command, so my next one was 0.1mm retract and then i push the 100mm.
And it works for me.

Re: Having trouble calibrating extruder steps per mm

My extruder has been creaking when extruding, so I checked the idler thing and i noticed it would momentarily stop. Pulled the door open and looked at the pulley on the motor and I think the locking screw wasn't tight enough so I tightened that.
Was hoping that was my problem but while the creaking stopped, it was still only extruding about 95mm instead of 100mm.

However I did what you did, set the new E value, reboot, retracted 0.1mm as the first command, and then extruded 100 and it was finally at just about 100mm 🙂
Will see how it performs from here. Thanks!