Extrusion Multiplier setting has no effect  

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yinglingd
(@yinglingd)
New Member

The Extrusion multiplier setting has no effect to the extrusion width on my Mini. I followed the steps laid out here, using the Precision Method Cube. https://help.prusa3d.com/cs/article/extrusion-multiplier-calibration_5908

Using a micrometer changing the value from 1.051 to 1.081 had no effect.  I double checked and printed it a second time to make sure that I didn't accidentally reprint the first one without the additional multiplier and ensured that the g-code called out the correct value.  All the prints came out looking really good but all had the exact same wall thickness.

Earlier today I did the exact same process at work where we have a MK3S and it worked perfectly.  The first print at work the Extrusion multiplier  was 1.0 and the wall thickness is about the same as I am getting on my Mini.

Am I missing something? Is anyone else able to successfully increase their wall thickness with the Extrusion multiplier on their Mini with the Precision Cube?

Mini Firmware = 4.0.5  Test done with MatterHacker PETG Black

 

Posted : 02/07/2020 3:49 am
joan.t
(@joantabb)
Veteran Member Moderator

Does the filament weight value change between the original model sliced with  extrusion multiplier 1.051 and 1.081? 

if it does, that filament has to be going somewhere! 

what happens if you try a larger difference? 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 02/07/2020 4:34 am
kim-1
(@kim-1)
Active Member

I think it does have an effect but you have to change it quite a bit.   The change from 1.051 to 1.081 is only equivalent to o.oo13 mm and a typical micrometer accuracy is 0.001.   I did the calibration cube and, while printing, changed the flow rate from 0.95 to 1, 1.05 and 1.1.  If you do a change from 0.95 to 1.0 while it is printing the first layer you can see the difference.

Incidentally the mini, like others, changes the flow rate from 1.00 to 0.95 just before it starts printing properly - the display doesn't change - you have to go out and come back into the menu to see it.   I have found, with prusament pla,  I need the flow rate to be 1.00 (not 0.95) for the first layer,  but after that there are pros and cons.

See what you find.  I like joan's "measure the weight" - am going to try that.

Posted : 02/07/2020 10:26 am
clemens.m
(@clemens-m)
Reputable Member
Posted by: @kim-1

Incidentally the mini, like others, changes the flow rate from 1.00 to 0.95 just before it starts printing properly - the display doesn't change - you have to go out and come back into the menu to see it.   I have found, with prusament pla,  I need the flow rate to be 1.00 (not 0.95) for the first layer,  but after that there are pros and cons.

Take a look at the Start-G-Code sequence. You will find:

G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S170 ; set extruder temp for bed leveling
M140 S[first_layer_bed_temperature] ; set bed temp
M109 R170 ; wait for bed leveling temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
G28 ; home all without mesh bed level
G29 ; mesh bed leveling
M104 S[first_layer_temperature] ; set extruder temp
G92 E0.0
G1 Y-2.0 X179 F2400
G1 Z3 F720
M109 S[first_layer_temperature] ; wait for extruder temp

; intro line
G1 X170 F1000
G1 Z0.2 F720
G1 X110.0 E8.0 F900
G1 X40.0 E10.0 F700
G92 E0.0

M221 S95 ; set flow ... this is the important line. If you change the value in Slicer it will have no effect, because of this line !!!

Best regards, Clemens

Posted : 02/07/2020 10:31 am
kim-1
(@kim-1)
Active Member

Are you sure?  The documentation says 

Total flow rate = Flow multiplier in firmware (M221) x Extrusion multiplier in PrusaSlicer.

So I read that as meaning BOTH parameters can have an effect on flow rate.  So, whilst it is true that the flow multiplier dropping from 1.0 to 0.95 will reduce it, the Extrusion multiplier will still have an effect.  

But I see that this has been discussed at length before 😉  The conclusion seemed to be that the Extrusion multiplier (say 1.05) was reflected in different E values throughout the code - i.e. scaled by 1.05.   See https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-prusa-i3-kit-archive/extruder-calibration/#_ga=2.244856261.1576125828.1593678073-912822840.1573466564 Sorry I don't know a better way to refer to a post. Relevant bit is from mrmik 18/10/2016 2.12pm.

I have just done two slicings and compared and the above post seems correct.

 

Posted : 02/07/2020 11:56 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @kim-1

Are you sure?  The documentation says 

Total flow rate = Flow multiplier in firmware (M221) x Extrusion multiplier in PrusaSlicer.

That is correct, but possibly a bit confusing. The extrusion multiplier specified in filament settings is used at slice time. The results are calculated as part of the gcode generated by the slicer. Open a gcode file and you can see the E parameter on every G1 command for extrusion. If you tweak the extrusion multiplier, these values will change. Once generated, the gcode file is not modified or interpreted by the printer. The gcode commands are simply fed to the printer.

The M221 gcode command is applied to the printer at print time. The printer firmware modifies the amount of filament extruded. It has no knowledge of the individual gcode commands within the file being printed, or vice-versa. There is no way for one setting to be aware of the other or turn a setting "off".

You want to apply the extrusion multiplier in filament settings to compensate for variations with a specific filament type. Some brands are a bit less than 1.75mm diameter, for example. You want to apply a printer flow rate modifier to compensate for flow issues with any filament. Perhaps your extruder is pushing a bit too much filament, or a particular nozzle tends to over-extrude no matter what filament you're printing with. This is how Prusa is using the M221 modifier to adjust for different nozzle sizes.

Be aware that the M221 modifier is persistent. Once set on the printer, whether via the front menu or an M221 gcode command in the printed file, that setting will remain in effect until either explicitly changed, or the printer is reset or power cycled. I make a point of resetting M221 (and other values) at the start of every print in custom startup and end gcode.

This post was modified 4 months ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 02/07/2020 4:51 pm
clemens.m liked
clemens.m
(@clemens-m)
Reputable Member

@bobstro

That is a nice explanation (easy to follow) - just one question:

I built my own printer (very similar to a Prusa i3 MK2S) using a Ramps board 1.6 and an Arduino Mega. Challenge for me was to find out if I am able to set up firmware to get a nice printing printer.

At my printer the value for flow multiplier (firmware) is 1 - I only play around with the extrusion multiplier in PrusaSlicer. Why the hell is the value for flow multiplier per default 0,95?

Is it some sort of compatibility issue?

Best regards, Clemens

Posted : 02/07/2020 5:30 pm
kim-1
(@kim-1)
Active Member

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-others-archive/updated-slic3r-pe-over-extrusion-and-cooling-solved/#p59075

from Josef himself.

And @bobstro commented in Jan 2019

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/why-is-flow-set-to-95-as-standard/

Incidentally I also found the flow rate for larger layers (e.g. 0.3 ) was too high, although the reduced build time was very welcome.

Posted : 02/07/2020 5:55 pm
yinglingd
(@yinglingd)
New Member
Posted by: @kim-1

I think it does have an effect but you have to change it quite a bit.   The change from 1.051 to 1.081 is only equivalent to o.oo13 mm and a typical micrometer accuracy is 0.001.   I did the calibration cube and, while printing, changed the flow rate from 0.95 to 1, 1.05 and 1.1.  If you do a change from 0.95 to 1.0 while it is printing the first layer you can see the difference.

Incidentally the mini, like others, changes the flow rate from 1.00 to 0.95 just before it starts printing properly - the display doesn't change - you have to go out and come back into the menu to see it.   I have found, with prusament pla,  I need the flow rate to be 1.00 (not 0.95) for the first layer,  but after that there are pros and cons.

See what you find.  I like joan's "measure the weight" - am going to try that.

Are you sure about the 0.0013mm change?  A 0.03 increase on 0.45mm is 0.013mm.  The value that I used on the MK3S was 1.027 and that work perfectly.  There was a measurable difference from having it at 1.0.  

Also does adjusting the Flow Rate / Flow Factor do the same thing as the Extrusion multiplier?  It would seem like these are 2 separate things but can have a similar output but are not the same.

I see now in the g-code that the E value is directly increased by the Extrusion multiplier.  So that setting changes the g-code not a parameter in the printer when printing. thanks @bobstro and @kim-1 for explaining that.

Posted : 02/07/2020 8:39 pm
yinglingd
(@yinglingd)
New Member

@joantabb

Unfortunately I do not have a scale accurate enough to see a difference.

I printed another one with an Extrusion multiplier (EM) of 1.0 and was able to notice a change in wall thickness. ( I know that may value can't be 100% accurate down to 0.001mm using just a micrometer but I am expecting a greater change due this method working on the MK3S)

  • EM of 1.000 = wall thickness of 0.417mm  (0.45/0.417 = 1.079 error)
  • EM of 1.051 = wall thickness of 0.436mm (0.45/0.436 = 1.032 error)
  • EM of 1.081 = wall thickness of 0.437mm  (0.45/0.437 = 1.030 error)

I will tried printing another one at a EM of 1.111 (1.081 + 0.03) and see if that ends up correct. 

Posted : 02/07/2020 9:17 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @kim-1

[...] Incidentally I also found the flow rate for larger layers (e.g. 0.3 ) was too high, although the reduced build time was very welcome.

I've had a similar experience and have replaced the Prusa M221 line in startup gcode with my own variation:

M221 S{if layer_height >= 0.32}90{else}100{endif} ; compensate for thick layer heights

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 02/07/2020 9:59 pm
joan.t
(@joantabb)
Veteran Member Moderator

@yinglingd

if you look in the Slicer information window, it shows you the estimated  model weight if you reslice and compare the model with the lower extrusion multiplier, has the lower weight shown. 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 02/07/2020 10:08 pm
clemens.m liked
clemens.m
(@clemens-m)
Reputable Member

@bobstro

So you have the factor for extrusion in filament settings for every material with "1"?
Is that correct? (Because I make a filament profile for every filament I use on my self built printer)

Best regards, Clemens

 

Posted : 03/07/2020 7:51 am
kim-1
(@kim-1)
Active Member

@yinglingd

No - you are correct but the point still stands.  It should have said "The change from 1.051 to 1.081 is only equivalent to o.o13 mm and a typical micrometer accuracy is 0.01"

Posted : 03/07/2020 8:12 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @clemens-m
[...] So you have the factor for extrusion in filament settings for every material with "1"?

I start at 1.0 and adjust it based on printing a calibration cube. I usually wind up somewhere between 0.9 and 1.0 depending on the filament.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 03/07/2020 8:13 am
yinglingd
(@yinglingd)
New Member

I was able to get it to work.  After printing 6 cubes..

An Extrusion multiplier of 1.11 with a filament diameter of 1.74 gave me the correct wall thickness.  

So everything is working fine. I just needed to not compare it to the easy results I got on the MK3S.  And I am not sure why the initial calculation from an EM of 1.0 did not yield a linear result in the wall thickness on the Mini when it worked on the MK3S, other than the real world can not always perfectly calculated (though we can try).  A EM of 1.11 should over extrude and give me a 0.463 wall.  Maybe because it is a Bowden setup and/or how the hot end is designed in general.  Teaching Tech had a good video showing the design and some issues he had and perhaps there's a small gap in my nozzle that is allowing the increase in filament being pushed to not be directly pushed out the nozzle.  But I am just speculating and could be way off.     

Thanks everyone for your help.  I understand how this works much better now.

 

 

Posted : 03/07/2020 9:39 pm
joan.t
(@joantabb)
Veteran Member Moderator

Thanks for sharing with us.
Happy Printing! 

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 03/07/2020 9:43 pm
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