My filament recommends a max print speed that's 1/3 of the default  

RE: My filament recommends a max print speed that's 1/3 of the default

I have no idea, I would do a test print at Generic PLA settings and see if I like the quality, if the printer struggles, try a lower speed!
regards Joan

RE: My filament recommends a max print speed that's 1/3 of the default

I’ve printed polyterra at default speeds with a max volumetric limit of 12 set on my mk3. I’ve got a nozzle x which is a steel nozzle so I usually bump my temps up 5-10 degrees and I found it prints fine at 225, so about equivalent of 215 with a brass nozzle. I started getting some very minor stringing at 230, but it wasn’t bad, just spiderweb thin which a blue flame lighter gets rid of in seconds, so that’s what I used  for slightly better layer bonding (as I mainly print functional items). Iirc I think the fastest speed was infill at 120mm/s. 

The website does say that some printers can print it at up to 140mm/s though. Best thing is to do as Joan suggests and do a couple of tests to see what suits you. 

RE: My filament recommends a max print speed that's 1/3 of the default

Dropping it to 5 didn't have any measurable impact on the print time, so maybe 15 is some theoretical max that can rarely be achieved anyway?

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You only see the highest speeds when printing parts near the max dimensions of the bed.  On small parts each strand is laid before the printer can reach top speed.

The defaults are just that, defaults.  Each filament manufacturer knows what parameters suit their own filament best - but if you're willing to risk slightly lower quality you're free to experiment.

Cheerio,

RE: My filament recommends a max print speed that's 1/3 of the default

Oh it can be reached, it depends on many factors, like infill pattern chosen as well as your defined speeds. For most prints though you usually dont get anywhere near.  When you have sliced just use the volumetric flow visualisation option on the preview to see what each part of your print is reaching.  

15 is slightly optimistic anyway, 12 is a more realistic safety value from what testing I’ve seen. At least for a stock setup. 

RE: My filament recommends a max print speed that's 1/3 of the default

Ok, thanks.

Anyway, back to my original point.  Does it make sense that a filament recommends a limit of 5.6 mm³/s? 

RE: My filament recommends a max print speed that's 1/3 of the default

Not really no for pla. Manufacturers recommendations are conservative usually. Given the sheer variety of different printers and hot ends out there it’s actually impossible to give valid numbers.  Just do some simple tests to work out what works on your printer. That’s just standard when trying a new filament anyway.
Start with Prusa’s by closest basic profile, try and then adjust. Don’t get hung up on numbers from the internet, even if they are from a manufacturer. 
Unless they can say something like tested on a xxxx at yyyy we found such and such and those conditions happen to match your exact setup. 

RE: My filament recommends a max print speed that's 1/3 of the default

I have printed Polymaker Polyterra at Prusament settings without an issue.  

RE: My filament recommends a max print speed that's 1/3 of the default

How can I test printing at 15 mm³/s?

RE: My filament recommends a max print speed that's 1/3 of the default

Look up testing your printers max volumetric flow rate. There are threads and articles on it. As I said it’s rare for an actual print to get that high so it usually requires specially designed models sliced with very high speed settings or another way is to extrude straight down from a height and see when the extruder starts skipping.  You can work out the maximum rate at which the extruder can handle that material that way. 
Is there some particular reason you want to check that the maximum will work with the filament ?  Or are you trying to check what the maximum is with that particular filament ?

Linear speeds are often limited for quality results

Posted by: @tt-4

[...] Anyway, back to my original point.  Does it make sense that a filament recommends a limit of 5.6 mm³/s? 

To be correct, they cited a recommended maximum linear speed (70mm/s), not a volumetric rate limit. This likely has more to do with filament adhesion and printing characteristics. To answer your other questions:

• If you use larger nozzles, you're more likely to approach the maximum volumetric rate (speed) set in PrusaSlicer. With a 0.4mm nozzle, you have to really be pushing things on larger prints.
• Even with a large nozzle and high capacity hotend, filament characteristics still put a limit on maximum usable speeds. I was surprised to find that PLA will have much more difficulty printing at high rates than PETG, assuming you're not after maximum quality.
• Those manufacturer guidelines are put out for new users using god only knows what printers. They give a middle-of-the-road safe range of values that will work for most people, and going slower is usually not a problem. You need to test to see what results you get with your settings to know for sure.

I've got some notes on "speed" in general, nozzles, and determining the maximum volumetric rate for your hardware that might be of interest.