I’ve had my new Prusa MK3S for two weeks so far. The first day was a blast! I had the machine unboxed, plugged in, connected to Octoprint, and then printing a dozen brackets for Tindie in about 20 minutes. I thought this was fantastic, but before the night was over, I even had a successful TPU print completed.
I knew before even ordering the machine that the Prusa MK3S would be much slower than I’m used to. My old MakerFarm Prusa i3 had monstrous stepper motors and an insanely powerful extruder. I was printing with a layer height of 0.3mm and 85mm/s perimeters, and I also had my acceleration cranked up to more than 2,500.
My friend Jeremy Cook is currently running a Kickstarter for his JC Pro Macro 2 Mechanical Keypad. I may be a little biased, but I do think you should go check it out!
Jeremy has been sending me printed circuit boards with just about every iteration, and I don’t want to tell you how much I’ve spent on Arduinos, rotary encoders, keycaps, and Cherry MX Blue key switches while building out macro pads!
JC Pro Macro 2 Mechanical Keyboard at Kickstarter
The Prusa 0.3mm Draft profile speeds were so much lower than what I’m used to. The Prusa community seems more interested in improving print quality. I’m often prototyping functional parts. If I can print a part in 45 minutes instead of 2 hours, then I might be able to print 4 or 5 iterations in a day instead of 2 or 3. That’s huge!
How far can I push the speeds without ending up with a sloppy mess?!
Let’s start by modifying the 0.15mm SPEED profile
I inched my way through the speed tweaks to the 0.15mm profile with many objects. I don’t think I have a handy comparison between the output of Prusa’s profile and my own. I’ll work on that printing some comparisons soon, but probably not until I feel like I’m done tweaking the 0.16mm profile.
For now, lets walk through some of the major changes. I’ll use the Marvin keychain and PrusaSlicer’s estimates for this. The estimates aren’t exact, but they’ll give you an idea of where we’re going. The Prusa 0.15mm profile says Marvin will take 48 minutes to print.
NOTE: I’m pretty sure the robot was printed with an early version of my 0.16mm profile.
The first thing I noticed was that many of the Prusa profiles default to grid infill. Cubic infill prints nearly as quickly, but it is stronger. Sort of. That means we can lower our infill percentage without significantly degrading the strength of our parts.
Switching to cubic infill increased print time by one minute. We are probably ending up with more infill due to the way the shifting layers of cubic infill are lining up with our spherical dude. If we drop down to 15% infill, we wind up at 47 minutes. Not a huge savings, but I would be willing to bet the savings would be more on a larger model.
The next thing I noticed was that the Prusa profiles don’t combine infill across layers. At a layer height of 0.15mm, you can tell PrusaSlicer to combine infill every two layers, and your infill will be 0.3mm. This means you spend half as much time printing infill, but you don’t have to give up the resolution on the perimeters.
Combining infill every two layers brings Marvin down to 41 minutes. These settings give a bigger speed up on larger prints. Our friend Marvin doesn’t have much infill!
On my old printer, I used to print with a 0.16mm layer height. I did this because my printer had no trouble printing infill at a height of 0.32mm. This is a tiny adjustment, but it brings us down to 39 minutes. We saved some time by going from 169 layers down to 158 layers.
At this point, we haven’t done anything that would significantly impact the appearance of the finished part.
Then I made small changes to most of the print speed and acceleration settings. I’m not sure I’m happy yet, but the rest of my changes bring the job down to 36 minutes.
This is as far as I got before I started messing around with the 0.3mm DRAFT profile. Just for reference, the slicer says Marvin will take 23 minutes with Prusa’s draft profile and 21 minutes with my draft profile. It isn’t a big difference with such a small part!
Working on the 0.30mm DRAFT profile
I worked on this profile while printing pairs of my CNC edge clamps. Prusa’s stock draft profile estimates a print time of 42 minutes.
I worked quickly on this profile because I was able to copy many changes from my 0.16mm profile. I bumped the layer height up to 0.32mm. That saved me two layers and one minute. We can’t combine infill layers here because 0.32mm is already pushing a 0.4mm nozzle to the limit!
Switching to cubic infill and dropping to 15% infill brought us down to 39 minutes. Then I dropped the solid top and bottom layers each by one. That brings printing time down to 33 minutes. With our thick layer height, that’s still quite thick!
The difference between 28 minutes and 42 minutes isn't that drastic! I'm sure you can pick out which pair is which. pic.twitter.com/z8FWExYibq— Pat Regan (@patsheadcom) August 15, 2020
Then I started bumping up speeds. During the test print, everything was looking fine, so I spun the knob on the printer to increase print speeds by 15% in real time. That worked fine, so I bumped just about everything up by another 15%. I don’t think I’m at the limit yet, but I’m pleased with where I’ve landed.
PrusaSlicer is estimating that a pair of my edge clamps will take 27 minutes to print. Better than that, though, I have real data! My fastest profile so far printed a pair of clamps in 26.5 minutes. Prusa’s draft profile took 43.5 minutes. That’s about a 60% improvement.
How terrible does your 0.32mm profile look, Pat?!
I took six sets of brackets to Brian Moses’s house. I told him he needed to identify which brackets printed in 26 minutes and which printed in 43 minutes. He couldn’t do it.
I too these to show @briancmoses last night. 2 were printed with Prusa's .3mm draft and too 42 minutes. I modified that profile. 2 were printed in 28.5 minutes, 2 were printed in 26.5 minutes.— Pat Regan (@patsheadcom) August 17, 2020
Brian couldn't figure out which were which. Neither can I. pic.twitter.com/UwjapmHGqm
None of them look amazing. They’re all drafts. I can see some minor differences in my fastest print, but it is more than acceptable and hardly noticeable.
What about acceleration?
I’m doing a bad job here. I’ve been bumping up acceleration numbers in the
Print Settings, but I haven’t yet been smart enough to bump up the maximum allowed acceleration numbers in the
I’m guessing that any acceleration bumps I’ve made haven’t actually been doing anything. Maybe I will work on that next time I’m testing?!
Acceleration increases made a HUGE difference in performance on my old printer. Without some strong acceleration, you just don’t get up to those 90mm/s infill speeds on small prints!
All the original Prusa 3D printers are fantastic machines. Josef Prusa has managed to cram so much functionality, reliability, and quality into a reasonably priced package. They will get beautiful prints right out of the box, and the community is huge.
Even if you’re like me, and you want faster prints out of your Prusa MK3S, you can definitely manage that too. It just takes a little tweaking, and I’ll most likely be pushing these profiles a little farther. I’m certain that some of these tweaks could be applied to the Prusa MINI as well!
What do you think? Am I printing fast enough? I’ve already made the big tweaks that each chop 10% or 15% right off the top of my print times. Should I be fighting for a few more percentage points of improvement? Have you tried my profiles? What do you think? Let me know in the comments, or stop by the Butter, What?! Discord server to chat with me about it!