Bigger nozzles, faster prints - what works?  

  RSS
Syd
 Syd
(@syd)
Eminent Member

New to 3D printing, I'm doing a bunch of printing of simple game organizer boxes and functional prints in PLA that don't have fine details or aesthetic value, and have been trying to research speeding things up.

From what I can tell, there are several obvious variables like nozzle size and layer height, and line width but also less initially obvious to me such as temperature and flow rate.

I could tackle this systematically by buying a few different nozzle sizes and playing around with Prusa Slicer settings.  Instead I thought I'd just ask:

Has anyone gotten significantly faster prints out of the Mini than the stock build?  How did you do it (nozzles, settings)?

Posted : 19/01/2020 4:40 am
bobstro
(@bobstro)
Illustrious Member

Not yet using a Mini, but my notes on using different nozzles are here, and customizing PrusSlicer profiles are here. Most of the info will apply to any FFF 3D printer. Specifics like hotend volumetric rate will vary. 

Yes, a larger nozzle may significantly shorten print job times while moving more slowly. 

This post was modified 1 year ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 19/01/2020 3:03 pm
3Dprintedgr and Syd liked
Syd
 Syd
(@syd)
Eminent Member

Thanks @bobstro, this is a real teach-a-man-to-fish resource!  I'm picking up some bigger nozzles and will work through your guide.

I would still appreciate case-specific results from anyone who has been successful at speeding their Mini up!

Posted : 19/01/2020 5:04 pm
Lichtjaeger
(@lichtjaeger)
Noble Member

Posted : 19/01/2020 5:18 pm
3Dprintedgr and Syd liked
Lichtjaeger
(@lichtjaeger)
Noble Member

In general, you print faster with larger layer height and larger extrusion width. You might need a higher nozzle temperature to keep up with the flow rate.

Posted : 19/01/2020 5:25 pm
Syd liked
Syd
 Syd
(@syd)
Eminent Member
Posted by: @lichtjaeger

In general, you print faster with larger layer height and larger extrusion width. You might need a higher nozzle temperature to keep up with the flow rate.

Appreciate this point!  What is your intuition on the target temp for PLA, given that the Mini's default temp is 215C, given the following?

Using @bobstro's guide, I have created in PrusaSlicer a Printer Settings profile for a .8mm nozzle with .2mm/.96mm min/max layer heights.

Also created a Print Settings profile for .3mm layer height using .96mm for the first layer and .8 for the external perimeters, and the rest "0" for the slicer defaults.

Slicing a few models I'm seeing estimates of roughly half the print times I was getting with the 0.4mm nozzle and standard settings, which is very exciting!

Posted : 19/01/2020 6:25 pm
Lichtjaeger
(@lichtjaeger)
Noble Member
Posted by: @syd
Posted by: @lichtjaeger

In general, you print faster with larger layer height and larger extrusion width. You might need a higher nozzle temperature to keep up with the flow rate.

Appreciate this point!  What is your intuition on the target temp for PLA, given that the Mini's default temp is 215C, given the following?

PLA is known to be less susceptible to temperature changes. The temperature range is usually specified as 190-220°C. If you use the 220°C, there should be no problems.

Posted : 19/01/2020 6:41 pm
Syd liked
bobstro
(@bobstro)
Illustrious Member
Posted by: @syd

[...] Using @bobstro's guide, I have created in PrusaSlicer a Printer Settings profile for a .8mm nozzle with .2mm/.96mm min/max layer heights.

Quick note: With a 0.8mm nozzle sticking to the recommended sizes, your maximum extrusion width should be 0.96mm (up to 120% of nozzle size) and maximum layer height 0.64mm (up to 80% of nozzle size). These are general safe numbers and you can always experiment beyond them, of course.

Also created a Print Settings profile for .3mm layer height using .96mm for the first layer and .8 for the external perimeters, and the rest "0" for the slicer defaults.

Slicing a few models I'm seeing estimates of roughly half the print times I was getting with the 0.4mm nozzle and standard settings, which is very exciting!

I've put together some notes on "the illusion of speed"as it relates to FFF 3D printing that you might find useful. Moving the nozzle faster has far less impact than the amount of plastic extruded during those moves. Understanding the relationship of linear speed, layer height and extrusion width on this lead me to appreciating that the maximum volumetric speed (rate) of the hotend is the key to avoiding extruder skips and jams as you increase nozzle sizes. The big win comes in when you can eliminate a perimeter on a large print.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 19/01/2020 9:05 pm
Syd
 Syd
(@syd)
Eminent Member

and maximum layer height 0.64mm (up to 80% of nozzle size).

But your notes ( http://projects.ttlexceeded.com/3dprinting_prusaslicer_profiles.html ) say:

Set layer height Max to the maximum layer height. 120% of nozzle diameter is the recommended maximum layer height.

Am I interpreting this wrong?  

your maximum extrusion width should be 0.96mm (up to 120% of nozzle size)

I see a "Default extrusion width" setting - is this the same as maximum?  I have the Default set to "0" so the slicer will compute.

As for speed, I was using the settings for the default 0.25mm DRAFT MINI profile.  It sounds like I should slow things down.  The Max volumetric speed setting is "0" in this profile; I can't figure out if that means no max speed is set, or if this is another value that is calculated by the slicer.  The Max print speed is set to 150mm/s, but based on your notes here: http://projects.ttlexceeded.com/3dprinting_nozzle_sizes.html that would be way to high for 8mm.  If I was doing .3mm layer it should be something like 11.5mm^3/s / (0.96mm * 0.3mm) = 39.93 mm/s, correct? 

And does that go in the "Max print speed" box? 😀 

Posted : 19/01/2020 10:29 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @syd
[...] Set layer height Max to the maximum layer height. 120% of nozzle diameter is the recommended maximum layer height.

Am I interpreting this wrong?  

Nope, you spotted a goof. I'll fix that, thanks. I think it's right everywhere else. Max 80% layer height, 120% extrusion width. The mind gets muddled when doing a lot of writing!

I see a "Default extrusion width" setting - is this the same as maximum?  I have the Default set to "0" so the slicer will compute.

Not the same exactly. It's the basis on which the others you see in that box are calculated. If you put 0 as default, PrusaSlicer will (IIRC) use the nozzle size, then scale the others based on that value. View the tooltips for each settings to see exactly what value is used.

The big advantage to using 0 for extrusion widths is that one print profile can be used with many nozzle sizes.

As for speed, I was using the settings for the default 0.25mm DRAFT MINI profile.  It sounds like I should slow things down.

I do slow things down a bit. I've got some sample profilesyou're welcome to try out that are as fast as Prusa's recommended defaults most of the time, but slow down a bit more for some settings. Of course, Prusa is always tweaking their profiles, so the changes may not be as dramatic as a few months ago.

 The Max volumetric speed setting is "0" in this profile; I can't figure out if that means no max speed is set, or if this is another value that is calculated by the slicer. 

0 just means use the defaults. There are 2 places Max volumetric speed (MVS) is set:

  • Under Filament Settings->Advanced
  • Under Print Settings->Advanced

At slice time, PrusaSlicer will use the most restrictive setting. If you look at the Prusa filament profiles, they use different values for different printers, but leave the Print Settings value at 0, so the filament speed is the one that takes effect. I like to set the Print Settings value as a master value (11.5mm^3/s) but feel free to experiment.

The Max print speed is set to 150mm/s, but based on your notes here: http://projects.ttlexceeded.com/3dprinting_nozzle_sizes.html that would be way to high for 8mm.  If I was doing .3mm layer it should be something like 11.5mm^3/s / (0.96mm * 0.3mm) = 39.93 mm/s, correct? 

That is correct. However...

And does that go in the "Max print speed" box? 😀 

This is the beauty of the MVS setting. You don't have to worry about it. PrusaSlicer will use the most restrictive of your speed settings or a speed that stays under the MVS value. This means you can configure your print settings to give the best finish and PrusaSlicer will take care of slowing down speeds. Again, one print profile can suit all purposes. It makes working with different nozzles so much easier!

This post was modified 1 year ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 19/01/2020 10:40 pm
benjamin.lakeit
(@benjamin-lakeit)
New Member

I used quite often the 0.6mm nozzle profile of the Mini with the stock 0.4mm diameter nozzle and did not experience huge issues with that. The print quality suffers a bit if you have not tuned the profile to your specific material but apart from that following CNC Kitchens observations regarding 50% extrusion width increase the MINI is drastically faster with the 0.6mm profile on the 0.4mm nozzle and the results where still good (I even ran some prints with 0.4mm layer height as a test and that worked pretty darn well 🤣 ).

Surely if you want to have very good looking print results you need to use the stock settings but if speed does matter - 0.6mm MINI profile with 0.3mm layer height is a fairly safe bet, even the 0.35mm DRAFT setting.

Posted : 20/01/2020 2:06 am
Syd liked
PJR
 PJR
(@pjr)
Moderator

You do need to be careful with your extrusion settings and as Bob has mentioned, keep the maximum extrusion width to 120% of nozzle diameter.

The Mini is built down to a price; the Bowden may complain (and fall apart) if you try to force too much plastic through the nozzle.

One of the big development problems was securing the Bowden tube.  The experience of MMU(1) showed that Festos would give up with too much pressure over time.  The method employed on the Mini for securing the Bowden was a better alternative to Festos but is still not foolproof.

 

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 20/01/2020 9:07 am
Syd liked
Olef
 Olef
(@olef)
Honorable Member
Posted by: @pjr

One of the big development problems was securing the Bowden tube.  The experience of MMU(1) showed that Festos would give up with too much pressure over time.  The method employed on the Mini for securing the Bowden was a better alternative to Festos but is still not foolproof.

Peter

Thank you for this info Peter. I have been wondering for some time the reason for this. I would like to replace the bowden PTFE for one with a larger ID but the olives that are required for these fittings are not listed as a spare part. I don't suppose you know the spec of the fitting and olive that Prusa are using by any chance?

Posted : 20/01/2020 11:13 am
Syd
 Syd
(@syd)
Eminent Member
Posted by: @pjr

The Mini is built down to a price; the Bowden may complain (and fall apart) if you try to force too much plastic through the nozzle.

Thanks for the heads up.  Is your intuition that trying a moderate layer height and 120% extrusion on an 0.8mm nozzle would exceed the capacity?  If not, where would you guess the breaking point is?  I noticed Prusa provides profiles for 0.6 but not 0.8...

Also, what does "complaining" sound like? 😆 

Posted : 20/01/2020 10:25 pm
Crawlerin
(@crawlerin)
Prominent Member

@syd

Mr. Bowden himself will visit you and whine in your face.

Posted : 21/01/2020 12:21 am
benjamin.lakeit
(@benjamin-lakeit)
New Member

@pjr

Thx for the hint - I was not aware of this fault point and will keep it in mind especially if future extrusion issues arise.

Posted : 21/01/2020 12:28 am
PJR
 PJR
(@pjr)
Moderator

@olef Olives should be available via chat.  If you ask them and they can't supply, please let me know.  Also please bare in mind that a larger ID in the Bowden may alter the printing characteristics, especially with softer filaments.

@syd I have no idea where the breaking point is.   What I am told is that this method is better than Festos.  I had 10 Festos give up on the MMU1 over a period of about 9 months, but I was really pushing limits with some of my prints (12MM^3/s)

@benjamin-lakeit I wouldn't call it a "fault point", simply a bottleneck with any Bowden system. PTFE is a very slippery substance and gripping it without distortion is always going to be very difficult.

 

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 21/01/2020 8:50 am
Syd liked
Share:

Please Login or Register