Heatbreak fan might be causing ASA/ABS warping  

RE: Heatbreak fan might be causing ASA/ABS warping

I will print and test it tonight.  I have had issues with adhesion with ABS on the textured sheet.  I might decide to try a gluestick if this does not work.  

Posted by: @jonniezg

I have noticed that my models that printed nice on MK3 and MK3S, heavily warp on my new MK4 with the same enclosure and with the same satin sheet. 

This issue has already been reported by quite a few people, and I suspect the culprit is very likely the new heatbreak fan that causes drought around the model, resulting the print to warp. 

There are already a couple of solutions offered by the community, such as this shroud that redirects the airflow intake away from the print bed. It seems to solve the problem with the warping!

Let's not forget that it adds weight to the print head, that will affect the Input Shaper. So that parameter should be added to the calibration procedure.

So my suggestions would be:

1. To test and consider officially adding this part to the final product.
2. To investigate how it affects the Input Shaper calibration and if it can be compensated in the hardware settings menu by adding "Additional Extruder Weight" (or similar) parameter, at least until a hardware accelerometer is added (hopefully).

 

RE: Heatbreak fan might be causing ASA/ABS warping

Hello, I have only printed asa twice with my MK4. No problems, but there weren't any parts that tend to warp either.

The fan thing sounds plausible and I'll definitely try it.

I would like to say the following about the input shaper in advance. Currently, maybe never, there is no way to use an accellrometer on the mk4.

I would like to refer to my thread where I provide test prints. Don't be misled by the title. The print of marlin and klipper is the same. Only how the frequencies are determined is different.

But everything is explained there and really easy.

Please no discussion here whether it makes sense. There are enough other places here in the forum.

Anyone who would like to try it is invited to share their findings there. What you can definitely see is how Input Shaper works.

You can use the gcode to change all parameters. Everything was explained in the first alpha. 

In this particular case, I don't think the weight matters. Printed in asa it should only be a few grams.

RE: Heatbreak fan might be causing ASA/ABS warping

..I have had issues with adhesion with ABS on the textured sheet....

We've had a few here who had problems with bed adhesion. Maybe that really creates an improvement in all materials.

RE: Heatbreak fan might be causing ASA/ABS warping

Posted by: @rainer-2

Hello, I have only printed asa twice with my MK4. No problems, but there weren't any parts that tend to warp either.

I just came up with this test model to verify the existence of the issue. It is based on a more complicated part that just kept warping, until I added the inner brim. I suspected it was the funnel in the middle making the drought that would cause the model to lift, until I added the inner brim too. However, on my MK3S+ it prints fine without the inner brim.

RE:

I've reprinted all MK4 parts in ASA in an enclosure at 42C ambient, satin sheet. Also did a few other prints before that. And no matter the geometry and size of the part, no matter the size of the brim - it warped badly, always starting from the same place - front left corner. I was about to print this shroud, but then my 3Dlac stick finally arrived so I tried that first and it makes everything weld itself to the plate. Parts come out beautiful now. So I never printed that shroud after all as I was satisfied with using the stick instead.

But without it? I wouldn't be able to print anything despite having over 40C in an enclosure. That draft is real, it even makes the brim lift and tear slightly lol. I see the fan % is lower for MK4 compared to MK3S+ (understandable, as the new fan is stronger and reaches much higher rpm), but still. I've never tried printing ASA on my MK3S+ so I cannot compare, but I can confirm that stock MK4 makes ASA warp a lot despite high ambient in an enclosure. At the same time 3Dlac seems to be strong enough to combat this perfectly, but a shroud is obviously a less hassle approach to this issue.

EDIT:
Actually, I also remember the warping being noticeably less severe the more parts there were on the plate. Meaning the warp must have been caused by the hotend hovering over the part for longer. This confirms the draft.

RE: Heatbreak fan might be causing ASA/ABS warping

I've gone through half a spool of ABS on the Prusa MK4 so far. No warping. I use a textured sheet and no enclosure. Room is a fairly constant 20 celsius. I printed the Big Einsy Case in ABS and it's over an inch high and uses most of the build plate. I used a 10mm brim all around to hold it onto the sheet and it stuck HARD. Even after the sheet had completely cooled I thought the texture was going to tear off with the print.

I've also printed the buffer wheels for an MMU3 in ABS with no brim. The wheels are 4mm high x 70mm diameter. None of them have warped. They self-detach after cooling.

The filament is Prusa ABS-T and I think I bought it back in 2019. It isn't stored in a dry box but humidity is never a concern where I live. I rarely clean the textured sheet.

I'm not denying your experience, just offering another data point. There's a variable here that's different between us and it's not the fan shroud or the heatbreak fan.

RE: Heatbreak fan might be causing ASA/ABS warping

Ever since my first MK2, through MK3, MK3S+ and now MK4 I have never managed to successfully print an object larger than some 2cm³ in ABS or ASA without a brim, not even mentioning without an enclosure. And I tried several brands.

I would really like to know the mysterious X-Factor that allows you printing ABS without a brim and without an enclosure, but that is not the point of this topic.

The bottom line is: I and some other people couldn't manage to print ASA on MK4 without warping. We installed the heatbreak fan shroud and the problems went away. So, it might be a good idea to investigate if it negatively affects some other aspects, and if not, to include it officially as a design improvement.

RE:

@ jonnieZG
thanks for posting and the link to my model 🙂

I did another test yesterday with and without shroud:

I think the result speaks for itself 🙂

Testmodel here: https://www.printables.com/de/model/568748-asa-warping-test-for-mk4

RE: Heatbreak fan might be causing ASA/ABS warping

Why is the second ("after") photo taken from a much higher angle?  With that high angle, it is difficult to see whether the corners separated from the bed or not.

Posted by: @daytrader

@ jonnieZG
thanks for posting and the link to my model 🙂

I did another test yesterday with and without shroud:

I think the result speaks for itself 🙂

RE:

because I was tired and did not pay attention 🙂 . . . I post then later two pictures from the same view 🙂

RE:

RE:

Here are the results of my test of the shroud linked above.  Conditions for both tests:

• Prusa Satin sheet, thoroughly cleaned before each print (Dawn dish soap & hot water, followed by 99% IPA).
• Bare bed (no glue or other adhesive).
• Prusa Enclosure (for both prints, temp started at ~35C and ended at ~38C)
• Standard MK4 (non-IS) printer profile, 0.4 nozzle
• Polylite ASA, dried several hours in dehydrator
• Prusament ASA print profile (no changes)
• No brims, internal or external
• Photos taken within 2o seconds of each print's completion, from same distance and angle (as close as possible with handheld camera).

Without the shroud:  Minor lifting at both front corners; somewhat more on right-front corner (which is where the most heatbreak fan turbulence would be expected). No lifting of rear corners.

With the shroud:  Minor lifting at left front corner, but somewhat less than before adding shroud.  No lifting of right-front or rear corners.

Verdict:  The shroud did reduce the warping.

RE: Heatbreak fan might be causing ASA/ABS warping

I have been using this shroud for a while, I can add another data point of it having a positive effect on ASA and PA printing.

RE: Heatbreak fan might be causing ASA/ABS warping

I sell one specific part on the web. Every week I get one or two order... so I regulary print this one part with Black Prusament ASA. I used my MK3s - no brim needed. Everything fine.

Now I changed to the mk4 an I already have 5 or 6 unfinished prints because the part is warping and get loose. I cleaned the sheets and try different thing. But nothing workes. On every sheet - it gets lose after 3-5mm height! I tried every sheet i have textured, satin and PEI(!!!) - this sucks... first I thought it was a problem with the IS - that is to strong movement...

I will try the shroud... - and report...

RE: Heatbreak fan might be causing ASA/ABS warping

I am having the same problem, actually also PLA warped on my MK4 (never happened on the MK3S). I am going to try this shroud and report

RE: Heatbreak fan might be causing ASA/ABS warping

I teied the new shroud and I can confirm it helps. However still it does not full fix the problem. I tried printing few small parts (20x20mm base) in ASA and still I see a bit of warping. On my MK3S by changing the z-height I was able to fix the issue over time and all the prints were pretty sticky to the plate.

I thought with the MK4 all of these problems were going to go away easily and instead still here...what else can we try? I tried playing with the z-heigh but it did not help...

I am going to print using mouse ears and see how it goes, but I would really be happy if I can print like before without warping

RE: Heatbreak fan might be causing ASA/ABS warping

Here are some findings re colorFabb ASA on MK4 and MK3S+ noted during printing of approx 180 parts. Approx 8.5 kg of ASA printed. 

The basic info...  .4mm Nozzle. The firmware in both printers was the OEM original. Prusaslicer. Used Prusa Connect to load .gcode to the MK4. MK3S+ as received from Prusa a year+ ago. Smooth plates. Both printers in large enclosures approx 48 x 48 x 36 in. high. Ambient temps outside enclosure ~ 20c. Enclosure temps ~ 25C start of print, ~ 30-35 C end of print. 

Parts approx 100 to 130 mm round with dome height of 12mm and 150 x 150 mm square with dome height of 12mm. 

Printed parts were rated for warp, top surface appearance, bottom surface appearance.  

Warp measured using steel ruler on edge across the bottom of the part spanning the width of the part in two directions. If gap at edge of ruler exceeded 1mm the part was deemed scrap. If warp less than 1 mm part was ruled acceptable. Most parts had warp .3-.7mm.  If top surface found to be slightly rough toward center, usually part was warped upwards in center. If bottom surface had what appeared to be faint sand bar like ripples, usually part was warped upwards in center. 

The following attributes were found to minimize warp. 

The "fan shroud" helped but effect was minimal. 

Fan 0, Fill 15%. Nozzle Temp of 250 first layer then 245. 

Bed Temp of 105 first layer then 110. 

These trends in temp were such that after the first layer the temp of the Bed moved closer to the temp of Nozzle. The idea was to reduce the delta between the bed and nozzle (filament as extruded) after the first layer. 

Layer height .20 first layer, .30 thereafter. 

Brim of 4 passes with .3mm Brim Gap used on square parts. Brim not used on Round parts. 

Draft shield did not have a noticeable effect. 

Biggest single improvement on square parts was use of bed adhesive. Fine spray of 3DLac. Cleaned with IPA after each print then reapplied thin coat. Larger round parts also benefitted from use of 3Dlac but effect less than for square parts. 

Parts printed 2-3 up on bed slightly more warp (.1-.3mm) than parts printed 1up.

Aside from challenges to minimize warp, the printers both performed perfectly. No crashes, no mystery reboots, no clogs or broken filament, even stoppages when filament was exhausted restarted smoothly once a new spool was provided.  Prusa Connect very helpful particularly tracking results, graphs, filament consumption etc. Found that the filament consumed predicted by Prusa Slicer and that reported by Prusa Connect vs weight of part were nearly always within 1 gram (parts weighed 30-60g depending on size and shape. 

RE:

Posted by: @kps

....

Biggest single improvement on square parts was use of bed adhesive. Fine spray of 3DLac. Cleaned with IPA after each print then reapplied thin coat. Larger round parts also benefitted from use of 3Dlac but effect less than for square parts. 

... 

Thank you for the extensive analysis, I am sure it might be of help to someone. But again, the purpose of this thread is NOT to teach the best way of printing ASA, but to identify what causes it to warp on MK4, while on MK3 it prints fine. 

The parts in question printed without any warping on my MK3S using pretty much the same settings AND the same satin sheet, while it warped on my MK4 until I and quite a few others installed the said shroud.

RE: Heatbreak fan might be causing ASA/ABS warping

Not to hijack the thread that I started, there is also another significant difference between MK4 and MK3 that might affect the warping, and that's the fan duct. The one that blows on the filament exiting the nozzle. There is an interesting project on Printables but I'd rather keep the discussion on it in a separate, dedicated thread.