Do the included printer profiles use a too high limit for the volumetric flow?
I have a specific model which a sliced for my default 0.4 HF nozzle and then a second time for a 0.6 HF nozzle. The estimated print time was reduced to one half.
Note, this is not a question whether a 0.6 nozzle always leads to faster printing times. I am aware that the effect depends on the model and that there are a lot of models where a 0.4 or 0.6 nozzle won't make a difference. This is not the point here as I have a specific model which largely consists of straigt, thin walls (~2mm) where the larger nozzle can actually play off its strengths and the slicer has already estimated a considerable gain.
I intend to print the model with a high-temperature filament like ASA. However, I have seen a lot of reports which claim that the printer and filament profiles in Prusa Slicer are using a too high volumetric flow limit. So the calculated reduced printing time is a false alarm and overly optimistic as the hotend won't be able to heat up the filament fast enough. Those reports say that a 0.4 HF nozzle and the gantry speed already max out what the hotend can melt.
The printer profile for a Core One with an ObXidian 0.6 HF nozzle and the filament profile for Prusament ASA will lead to load errors and a failed print. Allegedly, one has to cut down the volumetric flow limit in the profile to 50% of its original value to avoid a failed print. However, this will obviously lead to a print time identical to that of a 0.4 HF nozzle. So while the larger nozzle lays down thicker lines and higher layers, the corrected volumetric flow limit makes the slicer do so at a drastically reduced travel speed for the gantry to avoid overloading the hotend.
Is that true? Are the original printer and filament profiles broken? Is the slicing result
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You can try the speed dial on the front panel to experiment. I set it to 300 % frequently, the printer has survived so far.
I don't have a direct answer to your question but I noticed extruder clicking yesterday in ABS (generic profile, ElCheapo material - my job to dial it in, can't blame on the profiles). This was with the 0.25 mm nozzle but I had the same thought- too much material in too little time for the set temperature and layer height.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
Is that true? Are the original printer and filament profiles broken? Is the slicing result
The profiles are not broken, they are a starting point. If I'm printing something small or trivial then the built-in profiles are good enough. For large functional prints I have my own profiles that I've created starting with the PrusaSlicer profiles and running my own tests to calibrate for a given nozzle. The tests I usually run for a new filament are:
- Dry Filament - do not skip!
- Temperature tower - from OrcaSlicer
- Extrusion multiplier - 40x40x40 1 wall cube with no infill. Measure the walls with a micrometer.
- Retraction tuning - Orca
- Pressure Advance - Prusa Slicer Pressure Advance Test
- Volumetric Flow - from OrcaSlicer
- XY Shrinkage - Califlower Mk2
- Skew - Califlower
For each nozzle type and size I rerun everything except shrinkage and skew.
The default profiles are accurate enough for general printing, the predicted print times are very close too - in general, the more you edit the greater your responsibility for errors ... mostly you should only change settings for technical requirements - eg, increased interlayer adhesion or directional stiffness/resilience. Changes made for decreased print time almost always have to trade-off some other property so impacting print quality.
If the volumetric flow value is wrong the predicted print time is still correct as it's the time taken to complete the print-head moves; of course, if the rate is wrong the extrusion will be wrong, possibly impossibly so, leading to a failed print.
If in doubt, make a trial print of the critical section.
Cheerio,
RE: Do the included printer profiles use a too high limit for the volumetric flow?
I've found the "balanced" profiles extremely good. Most people should be making excellent prints without any adjustments if using standard filaments. I think the bridge settings leave something to be desired, but everything else is pretty good. The only routine change I make is to the infill pattern.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
However, this will obviously lead to a print time identical to that of a 0.4 HF nozzle. So while the larger nozzle lays down thicker lines and higher layers, the corrected volumetric flow limit makes the slicer do so at a drastically reduced travel speed for the gantry to avoid overloading the hotend.
Is that true? Are the original printer and filament profiles broken? Is the slicing result
Hello, yes, that's correct. The increased printing time is also correct. Whether the maximum flow rate is pushed through a 0.4 or 0.6 nozzle is irrelevant because it's simply the maximum changed flow rate. What else is the slicer supposed to do but reduce the speed when material is being pushed through the 0.6 nozzle that is designed for the maximum speed and flow rate of a 0.6 nozzle? In other words, the original maximum flow rate is calculated for the maximum speed of the 0.6 nozzle. And the 0.4 nozzle just happens to be 50% of the 0.6 nozzle.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
Imagine it like this: A garden hose, in its original configuration, has a flow rate of, say, 10 liters per minute. A fire hose, in its original configuration, has a flow rate of 100 liters per minute. When filling a pool, one takes an hour. The fire hose takes 6 minutes. But if you now limit the fire hose to 10 liters per minute using the slicer, then it will also take an hour. Now you need to translate that to the printer/nozzle.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
Obviously, nobody gets the question or does answer it. However, the question is in the post's title
Do the included printer profiles use a too high limit for the volumetric flow?
I am considering using a 0.6 nozzle instead of a 0.4 nozzle for a specific project with PETG. I am using PrusaSlicer and the default printer profile for my Core One with the correct nozzle size plus the filament profile for Prusament PETG. The slicer has already estimated a big advantage in printing time with the larger nozzle as my model is one of those specific models which largely benefit from a larger nozzle.
However, there are a lot of reports in the Internet which claim that the profile for the 0.6 are based on a too high cap limit for the volumetric flow which means the slicer produced GCode which led to a failed print as the Core One wasn't able to keep up the necessary flow. The only way how those people were able to get a successful print was by limiting the volumetric flow in the 0.6 profile to the same value as in the 0.4 profile which of course nullified any advantage of the 0.6 nozzle.
But this would basically mean that PrusaSlicer ships with broken profiles for the 0.6 nozzle which suggest a print time advantage that cannot be fulfilled. I am wondering if this is actually true. (I mean it wouldn't be the first time that some company over-promises and under-delivers.) In that case I would simply save my money for buying a 0.6 nozzle.
Imagine it like this: A garden hose, in its original configuration, has a flow rate of, say, 10 liters per minute. [...]
That wasn't the question how the math works. It should be quite obvious from my original post that I know how the math works. Here are the default numbers from the original profiles
Prusament PETG @COREONE HF0.6, Maximal Volumetric Flow: 30mm³/s
Prusament PETG @COREONE HF0.4, Maximal Volumetric Flow: 24mm³/s
Let's make the question blunt: Are the numbers sugarcoated?
[...] in general, the more you edit the greater your responsibility for errors ... mostly you should only change settings for technical requirements - eg, [...]
Sure, but that is a no-brainer. The more I change the settings, the more room for errors. And I am responsible for any settings which I change. But that hasn't been the question either.
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Prusament PETG @COREONE HF0.6, Maximal Volumetric Flow: 30mm³/s
Prusament PETG @COREONE HF0.4, Maximal Volumetric Flow: 24mm³/s
Let's make the question blunt: Are the numbers sugarcoated?
Of course they are. Prusa can't supply a profile for every combination. Not only does the geometry of the nozzle affect the flow rate but so does: the material the nozzle is made out of (brass, steel, diamond), the width of your extrusion line, the temperature of the nozzle, even the color of the plastic and how dry it is. If you want the optimized max volumetric flow for your setup for a large functional print you should calibrate it yourself. Also, if you adjust max flow you also need to adjust the speed parameters as well.
For myself I don't care about speed for a functional print, I care about quality and fit. That's why I don't use high flow nozzles and I have profiles tuned to the exact filament and nozzle combination.
I use a 0.6mm nozzle not to save time, but to increase layer adhesion and control warping depending on the material I'm printing.
You want to know what the ideal flow rate is for your setup? Run a temperature tower then run a volumetric flow test. Otherwise you are just guessing.
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Two thoughts (this isn't "experimentally proving", my 0.6 mm nozzle runs smoothly but I run structural profiles not speed):
When pushing volumetric flow rate to the limit, make sure the filament moves freely in the PTFE tubes.
I have generally good experience with oiling filament (the tiniest amount, just pull the first meters of filament through a greasy cloth to prevent tubes and material being "clean at molecular level").
The reasoning is simply, filament friction opposes the extruder's effort to push material through. And if it gets stuck repeatedly then comes loose, the force peaks will break your print, not the long-term average.
Check that the idler in the print head is moving smoothly - if pushing the springs gives a scratching sound against the screw threads, there is room for improvement. I have removed threads under the springs with key files, now it moves smoothly). I wouldn't set it awfully tight (as to cause friction from sideways loading of the gears, which works against the extruder) but of course it may not slip. Remember to recalibrate, if making changes.
Also, check for good thermal contact between hot end and nozzle (thermal grease) as the sensor is on the hotend side of the thread. This could matter at high flow rate, when maximum heating power is transferred through the nozzle's thread.
None of this has been systematically validated other than using it myself. But, making the box run like-clockwork as much as possible seems common sense when you're pushing performance.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
I misunderstood your question, please accept my sincerest apologies, sir. Given that the 0.8HF profile even specifies a maximum volumetric flow of 37 mm³/s, I would say the hotend can handle it. I only have a standard 0.6 mm nozzle which is listed in the PETG profile with a maximum volumetric flow of 17 mm³/s. So far, it has managed it and PrusaSlicer also displays the actual maximum volumetric flow as such in the analysis. I've also run the 0.4HF nozzle at 24 mm³/s without any problems. Ultimately, it will come down to a test, although it seems no one here in the forum has actually pushed the flow to its maximum and allowed 30 mm³/s + through. Was it definitely an HF nozzle and not a standard one that you found online?
RE: Do the included printer profiles use a too high limit for the volumetric flow?
I have generally good experience with oiling filament (the tiniest amount, just pull the first meters of filament through a greasy cloth to prevent tubes and material being "clean at molecular level").
Have you had any negative experiences with bed adhesion or layer adhesion? Is there a potential for ignition? Or do you push the oiled part of the filament through the extruder without printing? Do any deposits form? What kind of oil are you using?
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Have you had any negative experiences with bed adhesion or layer adhesion? Is there a potential for ignition? Or do you push the oiled part of the filament through the extruder without printing? Do any deposits form? What kind of oil are you using?
I learned of this from "@digibike" on the German language forum (ideally, just search for it - long and informative posts, "a decade of experience" doesn't seem exaggerated). It used to be established practice in the DIY days, unfortunately before my time in 3D printing.
Personally I use a bottle of cheap viscous mineral oil (but not the cheapest cr*oomph from Ebay - resin and acid free, of course) from the hardware store's bicycle department ("sewing machine oil" is popular in German language). Original posts recommend plant oil, personally I feel better about something that is long-term stable = doesn't oxidize.
As a mental picture, imagine a violin string treated with resin. That is the effect you absolutely do not want, fortunately destroyed by a few molecules' worth of anything greasy.
Layer adhesion, oil kills it as a consistent film but the assumption is that the extruder mixes it into the volume, turning it into a PPM ("parts per million") contamination. The amount, say a few drops per kilogram, is clearly in that range and it needs very (very. Very!) little to be effective.
RE: Do the included printer profiles use a too high limit for the volumetric flow?
Does the profile take the nozzle material in consideration? As I understand hardened nozzles are less heat conductive as a brass nozzles.
So max flow through a 0.6 brass or 0.6 hardened nozzle should be different.
And you are talking about an ObXidian nozzle, what about those cited tails from the internet where people claim the max flow is not reached?
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Does the profile take the nozzle material in consideration? As I understand hardened nozzles are less heat conductive as a brass nozzles.
So max flow through a 0.6 brass or 0.6 hardened nozzle should be different.
And you are talking about an ObXidian nozzle, what about those cited tails from the internet where people claim the max flow is not reached?
The PrusaSlicer builtin profiles are calibrated against brass nozzles, e.g. the CHT that ships with the Core One. For other nozzle types the standard profiles are fine unless you are printing large functional parts that require precision. If so then flow (amongst others) needs to be determined experimentally.
As for the internet saying "nozzle XYZ doesn't reach advertised flow rates" there is so much to unpack here. Flow rate for what material? At what temperature? At what layer height and extrusion width? As for people mostly printing functional parts, high flow and speed just get in the way.
One interesting thing I'm finding is that the PrusaSlicer profiles, even for Prusa filament are conservative. Especially in regard to material shrinkage and extrusion multipliers. That's why, unless I'm printing a Benchy or Gridfinity box, the stock profiles are not good enough and need to be calibrated.