Feature request - Extrusion multiplier - where is it?

[pieri70 1]

On 12/19/2018 at 2:17 PM, ahoeben said:

Cura has a setting called Material Flow, which does exactly the same as an extrusion multiplier in the slicer.

Yes but that works on profile level. What I mean by multiplier is something relative to material (filament) setting.

Anyway if you change the filament diameter in filament settings you achieve the same result as a multiplier variable

[lostinacrowd 0]

On 3/15/2019 at 3:17 AM, pieri70 said:

Yes but that works on profile level. What I mean by multiplier is something relative to material (filament) setting.

Anyway if you change the filament diameter in filament settings you achieve the same result as a multiplier variable

 

This is something that I had to do in the Makerbot software as well since they didn't have any kind of "multiplier" way back when. Like you said it does the same thing, but it would be nice to keep the diameter set to the actual diameter and have a multiplier along side that.

[gr5 1,265]

It's called "flow".  If you set flow to 200% then that is the exact same thing as "material multiplier=2".  It will increase the extrusion values by whatever you set the flow to.  It will *not* create a "flow" gcode.  It will just increase all the extrusion values by the flow value in cura.

 

 

[pieri70 1]

16 hours ago, gr5 said:

It's called "flow".  If you set flow to 200% then that is the exact same thing as "material multiplier=2".  It will increase the extrusion values by whatever you set the flow to.  It will *not* create a "flow" gcode.  It will just increase all the extrusion values by the flow value in cura.

 

Yes, but as I said above  that works on profile level. What I mean by multiplier is something relative to material (filament) setting.

Let's say a given kind of filament always overextrudes. It is more reasonable to have an "extrusion multiplier" at filament setup level not at profile level.

What I usually do, after fine tuning steps/mm for the extruder, is to print a sigle wall/well know thickness  hollow cube, I measure and compare what I set as wall thickness and what my printer executes.

With this I have a ratio between the real and desired thickness, that is an extrusion multiplier.

This is good for a given kind of filament printed at a given temperature with a given speed, but I'm lazy so I consider it for my filament @print temperature.

Then in S3D I used this ratio that is coupled with a given filament.

In Cura there is not this option, so I change filament diameter, that is the same.

[gr5 1,265]

Ah.  I get it now.  Yes you still want flow.  You can create a separate profile for each filament type (as Ultimaker has done as well).  Because different types of filament need different temperatures, fan speeds, and flow.

 

Ultimaker has over 100 profiles e.g. fast-ABS-0.2     fine-ABS-0.1    fine-PLA-0.1   etc. There are a lot of combinations.  If there were only 10 material types and 3 profiles for each type that would be only 30 profiles but some (like PLA) have more.

[kmanstudios 1,038]

It is also better for you to create your own profiles rather than depend on a blanket profile when it comes to materials as different manufacturers version of a material does vary as well as the machine it is printed on as well even the colour of the material.

[ahoeben 752]

I am working on a plugin that will let you add more settings to the Print Settings for materials on the Materials pane of the Preferences:

At its simplest, it just adds the Flow setting to the Materials pane. Note that if you have a Flow values specified in a profile or in the sidebar, that value still overrides whatever you set in the material.

[yellowshark 148]

Funny how we all do different things to get the same result. When you say "...if a filament always over-extrudes" I would say it does not, you always have the wrong settings. Get the settings correct and you do not have to muck around with flow%. I guess we come at this from different perspectives and probably nothing wrong in that. I use 70% flow for 1st layer, along with standard print temp (i.e. I do not set a different 1st layer temp) as on my printer flow % changes and stabilises a lot faster than a temp. change. And for everything else on all filaments/colours etc. I use 100% flow. I control my extrusion, i.e. no under-extrusion and no over-extrusion, with the temperature.

[pieri70 1]

On 6/19/2019 at 2:47 PM, yellowshark said:

When you say "...if a filament always over-extrudes" I would say it does not, you always have the wrong settings.

 

What I usually do is set the correct filament extrusion length and steps/mm measuring with a caliper the length of filament extruded by the machine at printing temperature.

When I'm sure that when I tel my printer to extrude 100mm it extrudes 100 mm with less than 1 mm error I save my steps/mm into eeprom so these will be my correct steps/mm for that particular extruder for all my filaments.

Then with a given spool of material, exmple PLA 1,75mm orange, I perform a thin wall calibration, that is a cube with single wall shell @known wall line width (ex 0.4mm) no infill and .

If with these settings I obtain a wall 0.44mm thick I'm in overextrusion and I assume that this kind of filament is alwais printing like this if I don't correct with flow or filament diameter or extrusion multiplier or whatever it is called.

So in this particular case 0.40/0.44 is 0.91 extrusion multiplier in S3D word or 91% flow in cura.

In my case using Cura I correct the filament diameter (1.75mm) in material management that is the opposite (0.44/0.40)*1.75mm=1.92mm

 

Are these wrong settings for you?

 

[yellowshark 148]

Lol, yes and don't know. The process you use for calibrating the extrusion length is pretty much the same as me except that I look for tighter tolerance, say 50 microns not <1000. When I start the calibration I do not extrude filament, I measure the movement of the nozzle and once I think the calibration is good I validate/fine tune the calibration by printing and measuring filament.

 

Wall thickness and over extrusion. Not a simple subject but my view is that you are probably not over-extruding and my suspicion is that you nozzle diameter is 0.44 and therefore your Cura settings are wrong and line width and nozzle should be set to 0.44. I may be wrong but all I can say is that I had exactly the same thing a couple of years ago and corrected my Cura settings to 0.45 and saw improvement in my surface quality. It is probably worth pondering on this and trying some tests.

 

Somebody, I think @geert_2, machined himself a probe with increasing diameter so that he can measure the internal diameter of his nozzle.

[pieri70 1]

Quote

Lol, yes and don't know. The process you use for calibrating the extrusion length is pretty much the same as me except that I look for tighter tolerance, say 50 microns not <1000.

 

How do you measure 50µm filament length? I mean, how can you take such precise measure from the entrace of extruder to a given length of filament? I use the caliper and a pencil but the trace of pencil is larger than 50µm..

 

Quote

When I start the calibration I do not extrude filament, I measure the movement of the nozzle and once I think the calibration is good I validate/fine tune the calibration by printing and measuring filament.

 

You mean movement of the extruder?

 

Quote

Wall thickness and over extrusion. Not a simple subject but my view is that you are probably not over-extruding and my suspicion is that you nozzle diameter is 0.44 and therefore your Cura settings are wrong and line width and nozzle should be set to 0.44. I may be wrong but all I can say is that I had exactly the same thing a couple of years ago and corrected my Cura settings to 0.45 and saw improvement in my surface quality. It is probably worth pondering on this and trying some tests.

 

Nice point! I never thought about it..

But I think that if you change your nozzle diameter you obtain something similar to change your filament diameter..

I mean, if you tell Cura that you want to print a .40mm wall with a .44 nozzle you are saying Cura to lower the filament extrusion, and this is similar to tell Cura to print with a larger filament, isn't it?

 

Quote

Somebody, I think @geert_2, machined himself a probe with increasing diameter so that he can measure the internal diameter of his nozzle.

 

Wow! Madness ;)

[geert_2 335]

56 minutes ago, yellowshark said:

...

Somebody, I think @geert_2, machined himself a probe with increasing diameter so that he can measure the internal diameter of his nozzle.

 

Actually, I sanded a standard injection needle of 0.41mm diameter down to 0.39mm, so I could use it to poke into the nozzle from the bottom, to clean it. That was its original purpose. After sanding, that needle's diameter gradually transited from 0.39 to 0.41mm. Measured with a good quality Mitutoyo digital calipers, +-0.01mm.

 

Also I cut off and rounded the sharp tip, to prevent damaging the brass nozzle (see photo below). Even the soft steel of this injection needle is much harder than a brass nozzle, so you could easily damage it.

 

The ability to measure the nozzle-diameter was a nice side-effect.  :-)  First I measure the needle diameter at several spots, and then gently (!!!) push the needle into the nozzle and see how far it gets.

 

At the very beginning, I could only get the nozzle in once it was 0.39mm. Even 0.40mm didn't go (+-0.01mm). Now, a couple of years later, it easily goes in all the way up to 0.41mm. So the nozzle clearly has worn-out a bit, from mainly printing white PLA, which seems slightly more abrasive than other colors, maybe due to filler particles? But it still prints fine.

 

But any thin wire strands, like copper wire, should also work.

 

However, for calibrating the flow, I just dial the flow-rate in until it prints nicely, and that is my setting (e.g. 105% for a certain material). I am not saying this is a good approach, but it works for me.  :-)  So I don't actually usethe  nozzle diameter, nor do any calculations.

 

At the time when I studied electronics (ages ago...), transistor component specs could easily be 100% off, capacitor specs also, and resistor specs were usually 5% or 10% off. So we learned not to care about accuracy while calculating things, it made no sense anyway, but to get the order of magnitude correct. And then we provided good feedback for stabilisation (most important), and a potentiometer for calibration if that would be desired. I still think that is a workable philosophy for subjects with lots of often unknown variables, like 3D-printing. You could calculate flow up to 0.01% accuracy. But then if there is some unknown resistance somewhere in the feeding traject, the indents that the feeder wheel makes into the filament could stretch maybe 20%, from square-shape to diamond-shape, causing an error of 20% in the feed rate. If filament diameter varies with 0.1mm (3.5%), cross-section surface varies with 12%, and so does your feed-rate.

 

So whatever method you use, if it works for you and you are happy with it, I think it is a good method.

 

See the photo for the needle (ruler is in mm and cm):

 

While we are at it: to clean the internals of the brass nozzle, I have a soft brass M3 thread that I use as a file to gently scrape the side-walls. This too has a rounded tip at the bottom to prevent damage. This doesn't really measure anything, but if it has difficulty going through the teflon coupler and/or the brass area of the nozzle, there is accumulated dirt, or a deformed teflon coupler, which could cause extra resistance and negatively affect the flow rate. So this gives a rough indication if the feeding traject in the print head is clear enough to let filament pass easily.

 

 

 

[yellowshark 148]

3 hours ago, pieri70 said:

 

How do you measure 50µm filament length? I mean, how can you take such precise measure from the entrace of extruder to a given length of filament? I use the caliper and a pencil but the trace of pencil is larger than 50µm..

No, I fine tune by printing a length of filament and measuring the filament on the print bed.  Lol as you say you cannot get that accurate with a pencil!

3 hours ago, pieri70 said:

 

 

You mean movement of the extruder?

Well yes, the nozzle is attached to the extruder but the point of measurement is the nozzle tip before the move and then after the move

 

3 hours ago, pieri70 said:

 

 

Nice point! I never thought about it..

But I think that if you change your nozzle diameter you obtain something similar to change your filament diameter..

I mean, if you tell Cura that you want to print a .40mm wall with a .44 nozzle you are saying Cura to lower the filament extrusion, and this is similar to tell Cura to print with a larger filament, isn't it?

No I do not say that. I tell Cura my nozzle is 0.45 and then change all my line widths to 0.45. I am not sure there is any point in telling Cura to print a line width different to the physical extrusion. People do but lol I have never understood why. That can only potentially introduce inaccuracies although admittedly at those dimensions it is probably not important.

3 hours ago, pieri70 said:

 

 

Wow! Madness 😉

 

[yellowshark 148]

Thanks for that @geert_2, riddled with common sense and as you say, fundamentally it is your end result that is important not the method you used to get there

[pieri70 1]

On 6/21/2019 at 4:31 PM, yellowshark said:

No, I fine tune by printing a length of filament and measuring the filament on the print bed.  Lol as you say you cannot get that accurate with a pencil!

 

I Still don't understand this method.

How can you measure the length of filament pushed by the extruder by measuring it on the print bed once it's printed?

Edited June 24 by pieri70

[Stuarts 0]

If you extrude 10mm of 1.75mm filament and print it as a stripe on the bed. You can measure the thickness and width of the extruded stripe and the length to calculate the volume extruded.

Its pretty easy to calculate the volume of 10mm of 1.75 diameter filament. If you compare them you can calculate a correction factor to extrude the correct amount of filament.

 

Stuart

[pieri70 1]

Ok, Got it now..

[Stuarts 0]

Of course, measuring the width accurately enough is another challenge.

[yellowshark 148]

Indeed, I am only concerned with the length in terms of configuring the e-steps

[gr5 1,265]

There is a problem with calibrating using wall widths.  There are features (bugs?) in Cura that make thin walls the wrong thickness.  You could call it a cura bug.  The fix is to set Minimum Wall Flow to something like 50.  If you aren't doing that then your calibration method is not so good.  Maybe a better test is to print a cube and then weigh it?

 

My own personal test for extrusion is to print a cube with 100% infill and increase the speed until it starts underextruding.  You'll see the gaps in the infill when it starts underextruding.  I find that if you keep the speed down then there is no need to set flow to anything other than 100% regardless of filament type (nylon, abs, petg, pla).