print speed increase?  

Speed and extrusion rate

Speed is an illusion. Take a look through the Techniques section for lots more notes, and especially the Calculating Maximum Volumetric Speed page. 

RE: print speed increase?

'"For I am a bear of very little brain, and long words bother me." ― a.a. milne.'

Thanks for the article, "The illusion of speed."  Correct me if I'm wrong, but you seem to be saying that this is complicated and there are lots of knobs to turn, per your Spock quote.  You are presenting many data points that I'm not sure how to process them to a conclusion.  I get it, it's very complicated.  That's why I came here, to see if any map had been charted on the topic.  It sounds like the answer is "no."  

I like the idea you presented, "try using the Preview function in PrusaSlicer to fine tune your print selections."  Checking max volumetric speeds, great idea.  However, I'm not sure how to turn all the knobs in the slicer to effect all the changes needed for the study.   Even pointers on how to approach sucha n experiment this will be helpful to me.

"If you really want to go down the rabbit hole.."   I'd rather not, but wondered if any of the relationships were published so I don't have to do so.  It seem like the relationship between print speed, extrusion rate, nozzle size, temperature, layer thickness with respect to object strength should be knowable.  I set esthetics aside for my application, but I see it plays in for most.  I get the feeling this is every man for himself.  This is surprising given everyone here is limited by time.  Note the thread below is received by cricket sounds:

"If the squeezing idea is right, then maybe I could increase the print speed if I also increase the extrusion speed? Has anyone documented the relationship, for example, assuming a linear relationship between them: ie, found k in extrusion_speed = k*printing_speed?"

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-others-archive/printing-speed-vs-quality/

Has anyone had any promising findings?   

RE: print speed increase?

you gave a pointer to these nozzle results which is very good, but, "indicates two dimensional thinking."

RE:

Posted by: @stellr

'"For I am a bear of very little brain, and long words bother me." ― a.a. milne.'

Believe me, I started keeping notes for the same reason. 3D printing has come a long way in recent years, but a lot of really useful information on the fundamentals is tedious to locate.

Thanks for the article, "The illusion of speed."  Correct me if I'm wrong, but you seem to be saying that this is complicated and there are lots of knobs to turn, per your Spock quote.

Fundamentally, it's not that complicated. It does help, or at least I found it helped my prints, if:

1. You have a basic understanding of what the various knobs do.
2. You twist the right knob.

You're on the right path just thinking about the problem. The Spock quote spoke to me after I watched and participated in several threads in which very smart people spent a lot of time chasing the wrong settings. My intent was to try to capture and distill some of that information for the next person. Sorry my post was terse, but I was writing it on my phone whilst waiting at the hospital yesterday!

 You are presenting many data points that I'm not sure how to process them to a conclusion.  I get it, it's very complicated.  That's why I came here, to see if any map had been charted on the topic.  It sounds like the answer is "no."  

There's a lot of good information out there. It's just not all in one place, nor well indexed. My notes pages are where I've tried to consolidate the information I found useful. Please don't take any of this as discouragement! I just wanted to point out that "speed" is deceptive in relation to a 3D process.

I like the idea you presented, "try using the Preview function in PrusaSlicer to fine tune your print selections."  Checking max volumetric speeds, great idea.  However, I'm not sure how to turn all the knobs in the slicer to effect all the changes needed for the study.   Even pointers on how to approach sucha n experiment this will be helpful to me.

I've collected a lot of information on PrusaSlicer here that might be useful. Some other resources:

• The Prusa Academy is being expanded to cover both slicer and printer topics for all Prusa products. Sadly, only available to purchasers of assembled printers it seems.
• The Prusa Basics of 3D Printing ebook provides some very rudimentary intro material. 
• The Prusa PrusaSlicer documentation homepage is under heavy development and are improving daily.
• The PrusaSlicer FAQ also contains useful information.
• Most of the information in the Slic3r Manual still applies, particularly for settings and functions under the hood. Some settings have been superseded in PrusaSlicer.

"If you really want to go down the rabbit hole.."   I'd rather not, but wondered if any of the relationships were published so I don't have to do so.  It seem like the relationship between print speed, extrusion rate, nozzle size, temperature, layer thickness with respect to object strength should be knowable.

The "big secret" that I alluded to (apologies for the Conan the Barbarian paraphrasing) was the concept of maximum extrusion rate. I'll try to summarize here.

• Every filament 3D printer has a maximum extrusion rate. No matter how earnestly one spins the front knob, there's only so much plastic the printer can melt and move to still produce good results.
• This rate is referred to as the Maximum Volumetric Speed (MVS) in PrusaSlicer, though I found it more useful to think in terms of rate to avoid confusion with the various linear speed settings.
• MVS is calculated as Extrusion Width X Layer Height X Speed (in mm/s). The lightbulb moment for me was when it registered that any increase to one factor impacts the others. With smaller (0.4mm or smaller) nozzles, you won't run into this often, but if you move to larger nozzles, this is very important. The square-cube law applies, so a seemingly small change in layer height or extrusion width can greatly affect the linear speeds that will produce good results.

For example, the Mk3 printer uses the E3D V6 hotend that has a (sometimes) advertised MVS of 15mm^3/s (the volume plastic it can melt and move). Not mentioned in that advertising is that this rate is for a standard E3D V6 with a 0.4mm nozzle printing PLA.

• Nozzle size matters. A 0.4mm nozzle is going to produce much more back pressure than a 0.6mm or larger nozzle. MVS increases dramatically as you move to larger nozzles.
• Material matters. I found that my maximum rates for PETG are much higher than what I can push with PLA. This is a generality, and you really do have to test for yourself to see what works best, but be aware that every filament has a limit as to how fast it can be pushed. And of course, just because you can doesn't mean you should. While I can push a lot of PETG quickly, the resulting prints may not be satisfactory for some uses. When I'm printing big chonky functional parts, I worry less about finish and appearance that might be more important for other users.

You certainly don't need to understand all of this in depth to be productive. I have found that being aware of these factors -- at least enough to know where to look for information -- makes troubleshooting common problems much easier. When something works at one layer but not another, considering all of the factors, not just "speed", helps.

I set esthetics aside for my application, but I see it plays in for most.  I get the feeling this is every man for himself.  This is surprising given everyone here is limited by time. 

It's a combination of time and the speed of change in this technology. More than once I've prepared documentation pages that were superseded within a week by a new release of PrusaSlicer. While this is a good thing, it's disincentivizing for anybody doing documentation. Fortunately, Prusa is dedicating resources -- more than most larger manufacturers in fact -- to building good documentation. In the meantime, we try to help each other, but most can only do so on a voluntary basis.

Note the thread below is received by cricket sounds:

"If the squeezing idea is right, then maybe I could increase the print speed if I also increase the extrusion speed? Has anyone documented the relationship, for example, assuming a linear relationship between them: ie, found k in extrusion_speed = k*printing_speed?"

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-others-archive/printing-speed-vs-quality/

Has anyone had any promising findings?   

That thread was posted a few months before I got my Mk3. There was another thread a few months later that I participated in pursuing much the same information. A lot of time was spent "speeding up" prints using speed settings. The end conclusion was that your printer can very likely print at rates that the filament itself can't handle, and that changes to layer height and extrusion width required adjusting speeds. Fortunately the MVS setting alleviates the need to do this ourselves. I'll see if I can locate and post a link to the big "how fast can you print?" thread that started me down this path. (Edit: Found it!)

Unfortunately, many such questions have been answered but can be overlooked in search results. I've benefitted from the patient responses from many of our experienced members over the years. (Hello Joan!) That's what motivated me to start assembling my own notes.

Just go slow and I think you'll find that, like many things, the 3D printing process is made up of a bunch of relatively simple factors all assembled into one larger whole. I find it useful to focus on one factor at a time until I understand it reasonably well, then move on to the next.

RE: print speed increase?

Many thanks, really gracious of you to be so helpful.  This is so fun!  

RE:

Posted by: @stellr

you gave a pointer to these nozzle results which is very good, but, "indicates two dimensional thinking."

Do you mean this?

Prusa summed it up nicely in their YouTube video on nozzle sizes.
  That’s like buying a DSLR camera and never changing the lens. It definitely works, but you’re limiting yourself.

I think that line is a good summary of why looking into larger nozzles is worthwhile!

RE: print speed increase?

The Prusa MVS setting is discuss here:

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

MVS, the first computer operating system I ever got near:  https://en.wikipedia.org/wiki/MVS

RE:

Posted by: @stellr

The Prusa MVS setting is discuss here:

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

Unfortunately, I'd only started collaborating with Prusa when COVID hit and wasn't able to contribute more to their efforts.

RE: print speed increase?

I just meant changing nozzle size is "one knob."  It probably opens up the rabbit hole a little, enough for me to fall into it.  I think I could keep this thread going for the next year...decade.

RE: print speed increase?

Posted by: @stellr

I just meant changing nozzle size is "one knob."  It probably opens up the rabbit hole a little, enough for me to fall into it.  I think I could keep this thread going for the next year...decade.

Please do! I'm happy to contribute what information I can, and there are other (no doubt smarter) people here that may only be able to respond to "interesting" threads.

It's fortunate that Prusa chose Slic3r as their original slicer as it was, and still is I believe, the only mainstream free slicer that even hints at the maximum volumetric rate being a factor. Early 3D printing forums were full of very in-depth discussions on these topics, but sadly some of those are no longer maintained. 

RE: print speed increase?

Posted by: @stellr

[...] MVS, the first computer operating system I ever got near:  https://en.wikipedia.org/wiki/MVS

Starting out as a "computer guy" in the early 1980s, I wound up responsible for the maintenance contracts for an IBM System/370 (IIRC). I didn't interact with it much, but I do recall the operators getting in trouble for opening up the datacenter (what was it called back then?) doors on a nice spring evening to "let some air in". I did love perusing the shelves of technical documentation that were the norm back then. There was a nice gent whose entire only job was maintaining an assembly program running on an old Honeywell system from the 1960s.

RE: print speed increase?

Like I said, I got in a hurry and printed a part at 200% (8.75hrs) not knowing what the implications were.  I think the printer helped me out with it's built in intelligence.  The amount, by weight, was identical to the same object printed at 100% (17.5hrs).  Yep, I was surprised.  It was pushing the same amount of PLA through.  True, the results were ugly (again the part is unseen in the application).  I'll compose some strength test in the coming days.

RE: print speed increase?

When I want something done in less time, I'll bump up the layer height, or if it's a test print, cut it to only the critical sections.

I know some have done experiments on getting a maximal throughput, but one tautology about 3d printing is that prints take time.

It's the old 'Do you want it done right, or do you want it done right now.  Choose one.'  😉

RE: print speed increase?

"done right" ... Well, I might have a weird, on-off here.  By "right" I assume esthetics is a part of the measure of whether it done right or not.  The part of interest here, while functional, is not visible (it gets encased in another part), so the esthetic variable goes to zero in the measure of what is right. That is, unless the esthetics are indicators of inherent weakness.  Appearance always seems to be highly important in these discussions, but not so here...maybe.  Looking at the surface of the 9hr print, it clearly has some surface flaws.  I assume those flaws are embedded as well, but I just don't know if they are significant to the part function.  I have to devise a measure of the strength before I go much further in the search.  I see s vice in my future.

So, I'm in a search to optimize speed and strength.  Yep, layer height, width, nozzle size, extrusion rate as suggested in "Speed is an illusion" will be adjusted in the search.

More to come.  Thanks for all the fish.

RE: print speed increase?

Posted by: @stellr

[...] So, I'm in a search to optimize speed and strength.  Yep, layer height, width, nozzle size, extrusion rate as suggested in "Speed is an illusion" will be adjusted in the search.

I've dumped notes on this topic here that might be useful. My chaotic on-the-fly COVID PPE printing notes can be found here.