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Never perfect first layer + warping  

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tantoui
(@tantoui)
Eminent Member
Never perfect first layer + warping

Hello,

After spending hours on prusa chat with no solution, I turn to the forum hoping to find better answers.

To add a bit of context: I've been making a living from 3D printing for over a year. I used to have 3 prusa mk3s and 3 prusa minis, which I replaced with 6 prusa mk4s. I bought the mk4s for the promise of a first layer that's always perfect and for the input shaping feature, with the aim of printing more parts without increasing the number of printers I manage.

However, from the start, and on all 6 printers, I've never had a perfect first layer. They're always over-extruded.

Prusa support has sent me replacement parts, i.e. thermistor and loadcell, but this has brought no improvement.

The only way I can get a perfect first layer is to lower the first layer temperature to 190°. Obviously, this causes warping problems.

At 210° I get a decent first layer, but I still have warping problems.

I should point out that this happens on a new, smooth PEI plate, cleaned with isopropyl alcohol, and I'm using 5.1.2 firmware.

The best temperature to avoid warping is 230°, but even at this temperature I have slight warping on the largest parts. Also, at this temperature, the first layer is so over-extruded/squished that the dimensions are no longer respected. My pieces no longer fit together. I end up with a significant elephant foot.

I print with esun pla, but I have the same problem with prusament.

On my previous machines, I had no trouble printing the same parts with the same filament, using a first layer temperature of 215°.

Do you have any idea where the problem might be coming from and how to fix it ? How can I improve the first layer and avoid warping ?

All in all the mk4 experience is a nightmare and I miss my reliable mk3s with which first layer was always perfect once the z offset was done well.

Thanks in advance for your help.

Posted : 12/02/2024 8:49 am
fuchsr
(@fuchsr)
Famed Member
RE: Never perfect first layer + warping

I feel for you. I kept my Minis because they're just fun to use, but I was planning to get rid of my Mk3S's. Now I'm holding on to one of them because the always-perfect-layer turned out to be anything but, although in my case I see it with PETG on textured. The load cell is magic when it works but alas that's not 100% of the time, whereas the Mk3 just worked once Live Z was dialed in.

Posted : 12/02/2024 1:21 pm
frebys
(@frebys)
Trusted Member
RE: Never perfect first layer + warping

Hello! That's funny, I just dealed with and fixed this problem myself yesterday. What causes the waves / ridges you see in the second picture appears to be a matter of the layer height being too low in relation to the amount of material extruded. So the solution is to either lower the extrusion multiplier or increase the layer height (both of which can be done within the PrusaSlicer settings). 

I encountered this problem when I printed PLA at 250°C (to increase shiny-ness, add:north's Premium Silk filament), but the increased temperature resulted in an increased flow. So I lowered the extrusion multiplier from 0.98 -> 0.90 and the result was perfect. But please, test it yourself to see if the settings work for you, and not only by printing a sheet but maybe something more complicated (like benchy).

Posted : 13/02/2024 4:39 pm
tantoui
(@tantoui)
Eminent Member
Topic starter answered:
RE: Never perfect first layer + warping

Thanks for your suggestion, unfortunately, if I lower the extrusion multiplier, I end up with underextrusion on the higher layers.

I don't want to increase layer height either as it will lower the quality of the print.

Posted : 13/02/2024 4:45 pm
frebys
(@frebys)
Trusted Member
RE: Never perfect first layer + warping

It's possible to raise the layer height of only the first layer, have you tried that? In the PrusaSlicer it's under Print Settings -> Layers and perimeters -> Layer height. 

Posted : 13/02/2024 4:51 pm
tantoui
(@tantoui)
Eminent Member
Topic starter answered:
RE: Never perfect first layer + warping

Oh right I forgot about this option. Will try, thanks

Posted : 13/02/2024 5:37 pm
frebys liked
tantoui
(@tantoui)
Eminent Member
Topic starter answered:
RE: Never perfect first layer + warping

No improvement at all with higher layer height.

Posted : 14/02/2024 10:25 am
frebys liked
frebys
(@frebys)
Trusted Member
RE: Never perfect first layer + warping
Posted by: @tantoui

No improvement at all with higher layer height.

If you would like, you could send me a .gcode file with a problematic print you've got and I can give it a try with my MK4. Just to see what result I get, you never know. If you'd like that, just make sure it's sliced with Prusament PLA och PETG (or add:north PLA or PETG) and with either a 0.25n, 0.4n or 0.8n. 

Posted : 14/02/2024 12:26 pm
Lynn
 Lynn
(@lynn)
Estimable Member
RE: Never perfect first layer + warping

I agree that the ridges appear because the nozzle is too close, but it appears from both your images that the wavy appearance is absent around the perimeters.  Is there any change that your build plate is high in the middle? The bed mesh level does a fairly good job of compensating,   but because of how it interpolates the  heights between the probe points, if a  one or more isolated points are abnormally high or low, then the BML adjustments may not provide  adequate compensation, for points adjacent to those areas. 

This has happened to me numerous times where I missed piece of filament debris under the build plant, and when I was fiddling with bed level modes on my MK3, and got one the screws out of flat with the others. 

Just a thought. 

Posted : 14/02/2024 4:55 pm
tantoui
(@tantoui)
Eminent Member
Topic starter answered:
RE: Never perfect first layer + warping

Thanks for your answer.

It's not related to the place on the plate. When I print a 6x6 cm part, edges are not wavy but the middle is. When I print a 20x20 cm part, it's the same, all the middle is wavy but not the edges.

I already tried to tighten the bed screws but they weren't lose, so no improvement from this.

Posted : 14/02/2024 5:45 pm
frebys
(@frebys)
Trusted Member
RE: Never perfect first layer + warping

 

Posted by: @lynn

I agree that the ridges appear because the nozzle is too close, but it appears from both your images that the wavy appearance is absent around the perimeters.  Is there any change that your build plate is high in the middle? The bed mesh level does a fairly good job of compensating,   but because of how it interpolates the  heights between the probe points, if a  one or more isolated points are abnormally high or low, then the BML adjustments may not provide  adequate compensation, for points adjacent to those areas. 

This has happened to me numerous times where I missed piece of filament debris under the build plant, and when I was fiddling with bed level modes on my MK3, and got one the screws out of flat with the others. 

Just a thought. 

I can concur with tantoui, whenever I get wavy bottom problems they never appear at the print edges / perimeters for some reason. 

Posted : 14/02/2024 8:13 pm
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