Limit extruder feedrate for printing and retraction

[MarkMan0]

Application Version 3.6.0

Platform Windows 10

Printer With Marlin firmware

So I'd like to have a feature to limit the maximum speed of the extruder, while printing. I've tried doing this by chaging the limits in firmware, but it made retraction slow too, obviously.

So what I imagine is a new setting in the speed tab, like retraction speed Extruder max. speed [mm/s] - lets say 3mm/s. Thats 180 mm/min

And then in the gcode it would be like: ..... M203 E180 ; set extruder speed for printing ; printing now G1 G1 G1 ... ;Now retract, reset feedrate M203 E... G1 ;retract G0 ;travel G0 G1 ; un-retract M203 E180 ; reset feedrate

Why I think this is good? We can easily measure the max. feedrate our printer can handle with certain filaments. For me it's 200mm/min. This value doesn't change for different layer heights, so no need to play with temperature/speed settings when increasing layer height.

The max print speed would be limited in firmware.

Edit: I'm a hobby programmer. The way I would go implementing this, is: stick an M203 at the beginning

before every retraction set M203 after every retraction, set M203

[Ghostkeeper]

This has been asked of us before but I can't find the original back right now.

We would prefer to implement this in a somewhat different way: Using inheritance formulas in the front-end. You would set the maximum flow rate as a setting in mm³/s, and the setting for the print speed would be a formula such as this:

speed_print = =max_flow / layer_height / line_width

And then the printing speed would be adjusted down if you increase the layer height.

What I'm not really sure about yet though is how that would look if there are also other constraints to the print speed, such as accelerations in the outer wall causing ringing, steppers losing steps when going too fast, etc.

[MarkMan0]

Sounds great! Looking forward to it :)

At first sight it doesn't look like it's going to cause ringing, you're essentially just adjusting the max print speed. The final formula for the speed could be something like: speed_print = min( (max_flow / layer_height / line_width), user_set_max_speed)

I would only use it to insure, that I'm not printing faster than my extruder can handle. I got the idea when printing 0.32 infill and 0.16 wall, at 100mm/s. The walls were fine, but the infill was under-extruded.

For now I'll write myself a parser

[MrStump]

This has been asked of us before but I can't find the original back right now.

We would prefer to implement this in a somewhat different way: Using inheritance formulas in the front-end. You would set the maximum flow rate as a setting in mm³/s, and the setting for the print speed would be a formula such as this:

speed_print = =max_flow / layer_height / line_width

And then the printing speed would be adjusted down if you increase the layer height.

What I'm not really sure about yet though is how that would look if there are also other constraints to the print speed, such as accelerations in the outer wall causing ringing, steppers losing steps when going too fast, etc.

Hi, any news on this? this really helpfull feature

[Ghostkeeper]

Not really, but it depends on the printer you're using. Realistically it's hard to get this sort of thing through for Ultimaker printers, since all of Ultimaker's profiles need to be re-tested then. For other printers we're dependent on people from the community that have those printers to test, but since they don't have a setting to test with it's not going to be easy for them. A bit of a circle of dependencies going on.

[MrStump]

Not really, but it depends on the printer you're using. Realistically it's hard to get this sort of thing through for Ultimaker printers, since all of Ultimaker's profiles need to be re-tested then. For other printers we're dependent on people from the community that have those printers to test, but since they don't have a setting to test with it's not going to be easy for them. A bit of a circle of dependencies going on.

may be just add setting for "extrusion speed" in the speed tab, or material tab? and user can calibrate it themself. it's like calibrate step/mm for extruder but trough hot nozzle, command "feed" 100mm and measure is it really go 100mm through extruder with hot nozzle or just 85mm. for ex. my extruder can melt plastic with 3.5mm/sec direct flow. with 0.8 nozzle and 0.4layer it can provide max feedrate is ~70-80mm/sec, with 0.3 layer it can 80-100mm/sec. for this moment i test it with every nozzle/layer change, but if we'll have setting like this then slicer will limit max print speed depends on "raw extrusion speed", not "feeder speed". for now it could be added in "experimental tab". really, it would be reeeealy helpful.

[Ghostkeeper]

If the "extrusion speed" changes, would it change the line width or the printing speed?

[MrStump]

It should limit printing speed. Because if I want smaller line width i can set it. But if extruder can't provide needful amount of plastic on current printing speed with current line width and layer height then printer should slowdown. For this moment with plugin "printer settings" i can set "maximum feedrate" but it limit whole extruder speed and i can't use retract.

[Ghostkeeper]

Hmm, I think the most major concern left then is that the printing speed settings won't work any more then. Either that, or the extrusion speed setting won't work if the printing speed settings are overridden by any profile.

[MrStump]

in my opinion "extrusion speed" should be in charge, by default it could be as lightspeed, but if user want to calibrate "melt plastic extrusion speed" then feedrate should be limited by it. For example i don't really know is my priter able melt "this plastic" through 0.8 nozzle with layer 0.4 at speed 100mm/sec. but if there will be an option "melt plastic extrusion speed" that i checked before (like 3mm/sec) then slicer limit feedrate speed to 92mm/sec, because slicer can calculate what really speed of "melt plastic extrusion speed" will be in that setup and i'm not :) i mean if through 0.8 nozzle with layer 0.4 at speed 100mm/sec my extruder should feed raw plastic with 3.5mm/sec - my extruder would'n able to do it right, gear start to slip on raw plastic, there is clogging in nozzle and print will not be successfull. in case when we have THAT option CURA will show me that speed of infill with 100mm/sec is "yellow warning" or just limit it when sliced. sorry for my not realy good english. Regards, Stump )

[Ghostkeeper]

You mean that there should be a "maximum extruder feed rate" setting, then, but one that does not limit the retraction speeds as well.

[MrStump]

yes. actually i don't know when CURA calculate actual speed of extruder feedrate, i think CURA do it only when it slicing. so it should limit whole printing speed limited with "maximum extruder feed rate" while it calculate all. by default it could be at "light speed" it's like "Minimum Layer Time", but vice versa

[perfessor101]

I would really like this feature too, a setting for the Maximum Volumetric Flow rate of the Extruder HotEnd combination. Quite often I'll set my speeds thinking I have things dialed in for that print and then ninety minutes into the print the extruder will start clicking causing under extrusion as it snaps back and possibly other imperfections as it snaps forward again. At that point I have to decide if I would rather have the extra imperfections or try again throwing out what has been printed so far.

CNC Kitchen has a video showing how at higher volumetric flows the amount extruded drops off and can be somewhat compensated for with temperature increases. This could help with keeping those volumetric flowrate inconsistencies in check .

[dariuskt]

That is a very needed feature for me too. With 0.8 and 1.0mm nozzles extruder becomes the only limit for print speed.

Looks like this feed limit should naturally behave like Minimum Layer Time. It is a dynamic limitation as Layer Height and Line Width may be variable through the print.

Units for this configuration aren't that important as mm³/s and mm/s are basically the same and cant change independently for a given filament width.

[sbstnzmr]

Hey. I would really love to see that feature too. Not only for the larger nozzle diameters but also for filaments like TPU this is really useful.

As far as my experiences with other slicers go I would assume an implementation liket this: For PLA afaik 12-15 mm³/s is a good starting point for a regular hotend. This should limit the maximum printing speed. Or not if you assume a 0.4 nozzle because your printer can probably not go that fast so your regular printing speed applies. It's basically a max function on your volumetric speed and your print speed settings. For a 0.8 nozzle and a 0.4 layer height it would automatically calculate the maximum speed and still respect your regular speed settings otherwise. For a volcano it's more in the 30 mm³/s department so I personally don't really need it however it does make a difference for common hotends.

For TPU/Flex this makes adjusting settings also much easier. You could just set your max volumetric speed to something like 1.5 mm³/s and assuming a .2 layer height and a .44 line width your print speed would cap at 1.5/(0.2*0.44). Like this I can basically print speed constrained materials without messing with print speed settings.

I know what to set manually but especially more inexperienced users who would try larger nozzles on a common hotend would benefit from not messing up the prints and clogging the hotend. And I just miss this setting since it seems like a calculation that could be possible.

[perfessor101]

For an ender 3 with a 0.4mm nozzle it’s closer to 6 or 7 cubic mm/s ... 50 mm/s with 0.5mm nozzle 0.635 mm line width and 0.24 mm layer height clicking away ... dropped down to 45%. So much easier to limit it by volumetric rate. Then if I make a mistake (Going too fast) I don’t have to slow everything down.

[AndrewEllis93]

+1. This is the primary thing that stops me from using Cura as much as I'd like.

[MrStump]

any news about Volumetric speed limits?

[Ghostkeeper]

Sorry, no, we haven't worked on this yet.

[Aggebitter]

Some addon to the tread. The Volumetric speed aka mm3/s is critical on all FDM printers! If you hit that limit under extrusion is a fact.

I had an issue with my bowden tube and made some tests and calculations (good page for the math and how to test http://projects.ttlexceeded.com/3dprinting_calibrating_volumetric_rate.html)

My results with a stock Volcano head 0.8mm nozzle on stock Flsun Q5 gave me this:

Filament: PrimaValue Black PLA

(bad bowden tube) Temp Max Extrusion speed mm3/s (F/60 * A (2.403 for 1.75) ) M109 S200 G1 E100 F200 8.01 mm3/s
M109 S210 G1 E100 F350 12.015 mm3/s M109 S220 G1 E100 F500 20.025 mm3/s

(changed to unbranded one laying around) M109 S190 G1 E100 F550 22.0275 mm3/s M109 S200 G1 E100 F600 24.03 mm3/s M109 S210 G1 E100 F650 26.0325 mm3/s M109 S220 G1 E100 F750 30.025 mm3/s

30mm/s is the max my setup can extrude in open air. That limit should never be passed. Adding a safety margin for back pressure when extruding will have to be applied but in my case that was needed when I printed at 0.10mm layer with a 0.8mm nozzle (yes it did print just fine at 1mm line width)

To control extrusion with mm/s instead of mm2/s gives you a lot of errors you have to tweek. -The gripping diameter of the filament pulley is depending on how soft the filament is. The gripping radius will change and thereby the distance per step will change. -The nozzle pressure depends a lot on nozzle temperature for each filament used -The layer height generates different back pressure especially when using "ironing" with a wider line width than nozzle diameter

By using mm2/s we will reduce the needed tweaking to just for each filament to for constants:

Temperature: C Layer height: mm Line width: mm Volumetric: mm3/s

And we will get max printing speed in mm/s by doing the math 20mm3/s @ 0.2mm layer and 1mm line width gives: 20mm3 / (0.2mm * 1mm) = 100mm/s max speed

After that calculation we can start doing all the nice printout tweaks //Agge

[Glodigit]

+1 on this

[sgessner]

+1 ; Would be nice to have that feature!

[controlflow]

+1, I really miss this option

[Malmik]

+1

[Jackjan4]

+1 however I would implement it as maximum volumetric flow rate since PrusaSlicer has it and its fantastic for working out what the extruder is capable to do with different filaments.

[rcmonitor]

+1 for mm/time unit setting (mm/s or mm/min). Volume of material may vary (the filament spool may be of let's say 2.90 instead of 2.85, or 1.70 instead of 1.75), but the performance of extruder on filament may not.

[conceptual-perception]

I have a Prusa i3 M3KS and ... changing out the nozzle from 0.4 to 0.8 ... broke Cura completely. I started a print and ... my Octoprint setup threw a M112 message. It took me a bit to understand what had happened, that Cura instructed the printer to send filament faster then the printer could safely extrude it. Thankfully, my printed detected this as a thermal runaway event and forced a reset.

I don't really see from a user perspective how this is possible, since the MVS value is the known limit. My E3D v6 hotend can only handle 15mm^3 a second. Where do I put this value into Cura? I thought adjusting the nozzle size would ... change other settings (it didn't), but ... idk if it's worth me going in and figuring out all the speeds for all the parts of the print. That seems like work software should do.

https://help.prusa3d.com/en/article/max-volumetric-speed_127176

The Maximum volumetric speed setting (MVS) is one of the most powerful features in PrusaSlicer. The MVS setting essentially creates a manager for the maximum amount of filament that the slicer will attempt to push through your 3D printer’s hotend.

This gives PrusaSlicer users a huge advantage. Rather than trying to calculate a range of speeds for combinations of different nozzle sizes, layer heights or extrusion widths, you can simply specify the speeds and settings you desire, then let MVS regulate speeds at slice time when and only if necessary.

I love Cura, but this missing, hurts.

[pemerick07]

+1 For this. I like Cura much better than Slic3r/PrusaSlicer, but I always miss this feature. It's also incorporated into Fusion 360 Additive as a maximum E feedrate for given hardware configuration.

[beamzer]

+1 for this, i came here looking for how to adjust this in cura.

[hasufell]

So what is the current workaround for this missing basic feature?

[perfessor101]

So what is the current workaround for this missing basic feature?

What I do is start a print … wait until the extruded starts clicking …throw that one out and adjust speeds down … start another print …. Wait until the extruded starts clicking and throw that out …

So far that’s what we do with Ultimaker cura.

[conceptual-perception]

I've been manually figuring out the speeds for my prints. I switched to a 1mm nozzle, and I went through and made sure the height x speed x nozzle isn't faster than the MVS.

My hotend can do 11.5 cm^3/sec so the maximum speed at a layer height of 0.2 is about 57.5cm/s.

On Mon, May 10, 2021 at 10:12 AM perfessor101 @.***> wrote:

So what is the current workaround for this missing basic feature?

What I do is start a print … wait until the extruded starts clicking …throw that one out and adjust speeds down … start another print …. Wait until the extruded starts clicking and throw that out …

So far that’s what we do with Ultimaker cura.

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[perfessor101]

I use adaptive layer heights … so I guess it’s one or the other.

[Ghostkeeper]

Cura 4.10 will contain a visualisation for the flow rate. It's not automatically adjusting settings to limit the flow rate, but it at least allows visualisation of it. See https://github.com/Ultimaker/Cura/pull/9410.

[fvrmr]

We have created a ticket for adjusting settings to limit the flow rate on our backlog. Devs see CURA-8282

[tastyratz]

There are per printer flow limits, but, they differ per filament. Think about all the weird changes you do black magic calculations around that could otherwise be measured and calculated.

Peak extruder flow for a printer as a whole. Peak flow for a filament based on temperature, we could even do a flow rate calculation 2d mapping against temperature (weigh open air output at xmm/s at xdeg, then again at higher speed or temp. It would make a more solid material profile where we wouldn't need to mess with extrusion multipliers or temps to indirectly change flow.

Earlier in this req mentions Marlin codes, but, I'm running Klipper for the advanced featureset and resonance compensation. This should be firmware agnostic.

[AbeFM]

I've seen the limit set per filament in the past, this can make a lot of sense... Although really it is a combination of material and heater block.... I was just checking the thread to request at least a visulalization, I'd discounted "flow" as being a percentage (flow/wall flow/prime tower flow).... Perhaps change "Flow" to "Flow Rate"?

Glad to see this is getting attention.

[rostislav-marinov]

If we remove some other factors and take only flow speed to be the only limit and have to be thinner layers prints faster than thick layers and slimmer line prints faster than thicker line. Than adaptive layers will print faster. Then you will have speed changing not only for features of the objects, but the layers it's self. Also you will not sit and calculate every speed for every layer hight/thickness combination.

I'm wondering... Maybe I can try to make a plugin. So you can set 8 mm³/s, as main flow, 4mm³/s for outer, 50% for overhangs, etc.

[Glodigit]

Is there a way to get Cura to compute the values by modifying the filament profile manually? Like print_speed = [max speed] or [max flow rate speed calculation]. I'd totally open up VS code for 30 mins and now I have a set + forget filament profile.

[AbeFM]

It seems a maximum extruder speed would work? I'm unclear what happens if you set a high speed line and are against a firmware speed limit - will the whole move slow down, or will you underextrude but move the printhead at the same rate?

When I look at code coming out of PrusaSlicer, it is aware of hitting that limit and orders slower moves where more material is coming out (in my case, thicker walls). That IS the purpose - to limit volumetric flow rates - which prevents jams and grinding. It is dependent on material (and to a degree, temperature).

It might be hard to implement (though not impossible as other slicers have done this for years). I can't tell if Rostislav's comment, while accurate, is saying we should or shouldn't do this because of x-y speed changes, but I feel we should.

Alternatively: Could you add a graphical only limit - when displaying the print speed graph, could areas which are over a particular print speed be highlighted as overhangs currently are?

[rostislav-marinov]

I'm currently testing different approach/workflow. Running Klipper on Modded Anet ET4x with bad hard to print PLA filament (cheapest locally made) on 0.3mm nozzle.

• Found my maximum flow rate and let say optimal is 70%-80% from maximum.
• Found my Acceleration Limits.
• Found my Linear/Pressure Advance (Klipper uses this this very good internally).
• Using Google sheet to calculate speeds. https://docs.google.com/spreadsheets/d/1reUdOvrVpZviGmEmnvC4giYMgKwU9U2PYtte8ioz1T4/edit?usp=sharing

Testing out those speeds atm.

[11iq]

I'm currently testing different approach/workflow. Running Klipper on Modded Anet ET4x with bad hard to print PLA filament (cheapest locally made) on 0.3mm nozzle.

• Found my maximum flow rate and let say optimal is 70%-80% from maximum.
• Found my Acceleration Limits.
• Found my Linear/Pressure Advance (Klipper uses this this very good internally).
• Using Google sheet to calculate speeds. https://docs.google.com/spreadsheets/d/1reUdOvrVpZviGmEmnvC4giYMgKwU9U2PYtte8ioz1T4/edit?usp=sharing

Testing out those speeds atm.

Could you add option to set nozzle size? Because setting the Volumetric rate to 8.6 mm3/s; line width to 0.72mm and layer height to 0.48 calculates the external wall to 0mm/s. Your calculator seems to calculate the speed very low compared to PS.

[rostislav-marinov]

Yep there is issue as the "safe" margin with the maximum speeds for external walls decreases. If you have like 75% for 100mm/s it should be 90% for 30mm/s or something like that. Also formula is quite simple ATM, sheet two I've made bigger data set and speedline is quite steep at the end, for me it should be a bit more straight so speeds are a bit more conserve and safer.

[Ghostkeeper]

It might be hard to implement (though not impossible as other slicers have done this for years). I can't tell if Rostislav's comment, while accurate, is saying we should or shouldn't do this because of x-y speed changes, but I feel we should.

I don't think any of the suggestions here are difficult to implement. The biggest problem is that all of these settings are a bit of a mess to the user and also overconstrained. If the user specifies 50mm/s, 0.2mm layer height and 0.4mm line width they are currently getting 4mm³/s. If the extrusion rate limit is set to 3mm³/s, they'll see that their speed is reduced everywhere and might be wondering why. Cura can't use both the correct speed and the correct extrusion rate. It's going to have to choose one over the other and the user must somehow be intuitively know why.

If we implement this feature via inheritance formulas in the front-end, we can make the speed setting automatically adjust based on the extrusion rate limit, and users may override that if they wish, but it won't work well for cases like Minimum Layer Time where the speed is adjusted in firmware. If we implement it in CuraEngine we can apply the flow rate limit everywhere correctly, but the user doesn't get any feedback on why it's not printing at the speed set by the speed setting.

Personally I'd think the solution in the front-end would be best. For the Minimum Layer Time you probably want to have a lower maximum extrusion rate anyway to make it cool better. There may be other speed adjustments I'm not thinking about now, but those are details we can print with.

I'm wondering... Maybe I can try to make a plugin.

If you're attempting this, I'd suggest taking a look at the Linear Advance Setting Plug-in to see how fieldOfView added a setting to the list safely.

[rostislav-marinov]

I'm wondering... Maybe I can try to make a plugin.

If you're attempting this, I'd suggest taking a look at the Linear Advance Setting Plug-in to see how fieldOfView added a setting to the list safely.

Thank you for the reference it's a very good starting point, as soon as I have a bit more time will try to make some basic implementation. From my tests main issues with this approach to speed are cooling/bridging and sticking/overhangs. You can have a bit higher speeds with thinner extrusion, but not as direct increase like with the simple shells and perimeters. Just to point again I'm currently testing with filament that is cheap and unreliable.

[tastyratz]

If the user specifies 50mm/s, 0.2mm layer height and 0.4mm line width they are currently getting 4mm³/s. If the extrusion rate limit is set to 3mm³/s, they'll see that their speed is reduced everywhere and might be wondering why. Cura can't use both the correct speed and the correct extrusion rate. It's going to have to choose one over the other and the user must somehow be intuitively know why.

This is easily handled with a notification on slice if desired "maximum speed calculated to 100mm/ss and restricted to 30mm/s due to flow rate cap. OR We don't. There are a lot of default parameters that influence how things are sliced. It can just be part of the calibration process people familiarize around new filaments, like esteps.

Yep there is issue as the "safe" margin with the maximum speeds for external walls decreases. If you have like 75% for 100mm/s it should be 90% for 30mm/s or something like that.

I'm thinking here we might be looking at some scope creep and overcomplicating some things or what this could/should be to start. This feels like it should be a maximum ceiling for extruder capacity. There are many many reasons why that may not be your optimum print speed. If you run at print head volumetric flow limits on a cheap printer with an e3d head it might shake itself apart and produce a hot mess print.

The goal here is to make a limiter, a safeguard against grinding some jams and risking that print. You could probably just set your speed to 1000mm/s and it would live at the volume flow limiter if that was the goal and your printer could handle it? Might not be a very pretty print though.

Also you will not sit and calculate every speed for every layer hight/thickness combination.

Maximum printhead/extruder safe limit is an easy calculation. Maximum capacity against print quality is something else entirely.

This seems to me like it belongs in the filament profile. What's safe for one color and brand might not be for another.

If we want to be extra fancy about it, this could be a scaled 2 point filament profile entry since we might have different temperatures at different sections of the print or for different jobs using that filament.

I.E.

Max flow 1: 8 Max flow temp: 190 Max flow 2: 10 Max flow temp: 240

We could also have a multiplier specific to the job itself so the calibrated filament profiles get left alone. I.E. Volumetric flow limit: 100%

[Life0fBrian]

Where would be the problem to implement that parameter into lets say Machine Settings -> Extruder X just underneath the Compatible material diameter. The default value shall be 0 and if a user changes this to his determined value maybe a short notice will remind him to the possible speed changes now caused by that limiting factor.

However an experienced user who wants to determine the max volumetric extrusion rate should already know that it affects speed during printing.

And yes there will always be people who just want to have a one button does it all setting/GUI and others who want to be able to change every single parameter

[TommyC81]

Just a note to say +1 for being able to set a volumetric limit. This will be even more important with Arachne.

SuperSlicer handles this nicely. Essentially, the most limiting of volumetric rate and max speed is used as the print speed. The volumetric rate is set per filament (just like temperature and other associated settings).

[Ghostkeeper]

Arachne (in its current state, not yet in the beta from March) has a setting to equalise the material flow by adjusting the movement speed, too. It causes the flow rate to be adjusted to the nominal flow rate for that line type (speed layer height line width), so it doesn't solve the original issue here which is about the flow difference between different line types. But it's related.

[Lecso11]

+1

[Arsoth]

+1, would love a max flow rate that I can put in. There's a reason it seems like Voron users all run SS/PS, because getting some of the granularity in Cura is a PITA. But Cura's UI is WAY better so... I would love it it had as many features and settings.