Prusament PLA @MK4IS settings - how will they change with speed
Since I tightened the thumbscrews holding in the nozzle I have had continued success printing with Prusament Black Galaxy. I have tried a few other brands but not extensively. Even detailed models have been really good. Shown below is a print of a great model of a Ford Bronco (@VitBudina on Printables). This was 3 hours and 8 minutes using default alpha MK4 IS slicing (vs 7.25 hours for a default 0.2mm quality on MK3s+). Detail is outstanding. No problems on the corners or anywhere else.
Made me wonder, though, not just how other filaments will fare at these speeds but how filament profiles may need to change for different speeds. Prusament PLA on a MK3S+ is 215/215. On regular MK4 settings Prusament PLA@PG is also 215/215. On the MK4IS, however, it is 230/225. Not sure if we will be slowing down print speeds from the input shaper settings once it is all finalized but I am guessing we will. My guess is overall filament temps follow somewhat of a sigmoid function as a function of speed (there is a low 180 or whatever and a high 230 or whatever for PLA). In between MK4 settings and MK4IS settings it may be relatively linear but either way I'm guessing there will need to be adjustments.
I am wondering if filament profiles will eventually have temp changes by speed and interpolate between values.
RE:
What I'm seeing is that it's all eventually going to come down to 1 thing -- how accurately controlled the temperature of the molten plastic coming out of the nozzle actually is.
This is currently just set using a simple method: set the temperature in the slicer, and rely on PID to take care of the rest.
Unfortunately, as you've hit on, this doesn't work reliably due to the new introduction of speed, mainly because the thermistor reading to feedback into PID is always going to read hotter than what the actual plastic extrusion temperature is, at a delta relative to the volumetric flow rate.
Now... if we could have some sort "temperature advance" function (a la linear/pressure advance) that takes into account the volumetric flow rate to feed back into PID, then we could potentially have a much more stable true extrusion temperature.
Until that point comes, I think the only real way is to incorporate it into the slicer (i.e. variable temperature, much like variable layer height)... or manually setting it based on the volumetric flow rate display and some trial and error.
So far I've had very good success with the manual method in slicer (add custom G-code at speed change point, M104 Sxxx), just going by what temperature seems to work best for which general flow rate. Pushing PLA to "240" for 15mm^3/sec is definitely not out of the question, especially for some of the hotter filaments (esp. matte). Some filaments (*cough* prusament *cough*) will have no problem operating in a wide range, so the temperature variation is hardly noticeable except for may some less shiny parts where the temperature actually dropped too much.
RE: Prusament PLA @MK4IS settings - how will they change with speed
I've got the same question. Prusament PLA prints much fast and excellent quality with IS/PA, but the temperatures for PLA of all kinds in the IS configurations are at least 10-15 degrees higher than the filament manufacturer's (including Prusa's) recommended temperatures, even for the first layer, which is not fast compared to the subsequent layers. Does that mean that for new brands or filament types we should start temperature towers at these kinds of temperatures? I don't believe that it is to compensate for filament vs thermistor difference, because the temperatures are different for the MK4 vs MK4IS. Are the flow rates really so high as to make that kind of a difference?
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Yes. They really are. As soon as you start pushing past 3mm^3/sec, you'll start needing to boost nozzle temperature.
Regular temperature towers won't usually give a good indication of this though, as the volumetric flow rate is usually limited due to layer time and overhang/bridging features. I found the best way by printing a cylinder in vase mode, and adjusting the temperature in steps. Basically, a simple temperature tower that you can use to set the volumetric flow rate constant for what you want to test, and see what minimum temperature is needed.
RE: Prusament PLA @MK4IS settings - how will they change with speed
Yep, agreeing with @carlmmii in principle. You push a material through a heated tube fast enough and it won't heat up as thoroughly (or evenly) as at a slower pace. I haven't played around with the added IS printer settings. I'm pretty much using stock 0.20 Quality on PLA and Speed on PETg. Still having good luck, still just curious if we will find variable temps will be beneficial.
I like the cylindrical (or other shape) temp tower just to see how to looks and handles curves and corners.
RE: Prusament PLA @MK4IS settings - how will they change with speed
Interesting to read this and understand a bit more about the relationship between speed, temp and the new IS profiles.
One slight negative I'm experiencing with the increased nozzle temps is more random oozing of filament from the nozzle as its warming up for the first layer. Not a massive issue in isolation, however its starting to impact the mesh levelling. What I think is happening is a little filament is left on the tip of the nozzle due to oozing at higher temps, which is impacting the bed levelling measurements via the loadcell. If I don't manually clean the nozzle just before it starts probing the bed, I get really rubbish prints with not enough "squish" of the filament.
RE: Prusament PLA @MK4IS settings - how will they change with speed
For me at least it appears to be doing all the bed leveling at 170. I imagine they picked 170 so most filaments would be soft to lessen the chance of damaging the bed. Maybe some filament types are a different temp not sure. I preheat to temp and let it thoroughly warm up and then clean the nozzle before each print (we do a lot of cosmetic pieces so I clean nozzles on all our machines anyways). After mesh leveling when it then goes up to the new higher temps I certainly get oozing right before the print. Usually the little purge line takes care of that, but not every time so I grab that ooze if possible before the print starts.
I haven't noticed any problems with the first layer due to ooze but that may be because of the extra cleaning I tend to do. I'm sure Prusa will be tweaking as they go along.
RE: Prusament PLA @MK4IS settings - how will they change with speed
I am experiencing the same problem on the FLSUN V400 delta. With infill at crazy speeds of 350 mm/s basically no filament is able to melt correctly even through a volcano. To be able to print, I need to raise the nozzle temp of 30-40°, so I print PETG at 245-250° and some High-Speed PETG at 275-280°, but even PLA must be printed at 230-240°.
So I was thinking to tweak PrusaSlicer, that knows the flow rate for a layer 😎 in a way that it alters the nozzle temperature based on the layer flow rate, in order to allow at peak of flow and speed to extrude material melted correctly. So when the layer flow rate changes, PrusaSlicer have to issue an adequate temperature change. It would be not perfect, but would avoid issues that I am having when I am at 250° and suddenly the layer become small and requires to be printed slowly, and suddenly 250° are too much.
I am not sure if I will have the same issue on the MK4 since it can't reach a print speed of 400 mm/s, but already over 200 mm/s the issue starts to happen.