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I'm getting a lot of blobbing and scuffing on top of my prints in PETG on my Ender 3 with AMH/DD. It doesn't seem to do this if the print doesn't have a flat bottom so much.

Mid-print model with blobbing/scuffing printing errors

I have the E-steps set to 130, which if anything is slightly under extruding vs the caliper measurements.

Any ideas how I can fix this?

Cura settings:

[general]  
version = 4  
name = Creality Ender 3 - eSUN PETG - Red  
definition = creality_base  

[metadata]  
type = quality_changes  
quality_type = standard  
intent_category = default  
position = 0  
setting_version = 17  

[values]  
cool_fan_full_layer = 3  
infill_overlap = 15  
infill_pattern = triangles  
infill_sparse_density = 10
ironing_enabled = False
ironing_only_highest_layer = True
material_print_temperature = 230
retraction_amount = 2
retraction_speed = 25
skirt_gap = 6
speed_infill = 30
speed_print = 35
speed_topbottom = 15
speed_travel = 250.0
speed_wall = 25
wall_line_count = 3
z_seam_x = 150
z_seam_y = 300

----
[general]
version = 4
name = Creality Ender 3 - eSUN PETG - Red
definition = creality_base

[metadata]
type = quality_changes
quality_type = standard
setting_version = 17

[values]
acceleration_enabled = True
jerk_enabled = True
layer_height_0 = 0.21
material_bed_temperature = 75
material_bed_temperature_layer_0 = 75
agarza
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Rob
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1 Answers1

4

Are you sure the 130 E-steps is correct for your extruder? You don't mention what extruder you're using, but presumably, it's something other than just moving the original extruder to a direct drive mounting position or that would be extreme over extrusion.

Assuming that's right, the most likely cause is having the nozzle too close to the bed, so that there's too little volume to fit the extruded material into.

Also, you almost surely need to increase your nozzle temperature a lot. I'd normally consider 235 °C the absolute minimum for PETG, and I can't get it to adhere properly below 245 °C with the stock Ender 3 hotend. Since you have an all-metal hotend you can go even higher. PETG likes to "scuff" like that when it's too cool, and when you travel over already-printed material, and the lowest layers are even more susceptible to it since the bed will be sinking a lot of heat out of the material as soon as it's laid down.

agarza
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R.. GitHub STOP HELPING ICE
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  • The bit that's really bothering me is... why are the perimeters always spot on? If you look at the picture, the perimeters are perfectly fine, and if the model is small with a minimum amount of infill, everything is fine too. It just seems to be these big blocks of flat infill that cause the problem. Thanks for the help I'll give this a go and see if changing temp or your other suggestions work. – Rob Aug 10 '21 at 19:01
  • If the perimeters are printed first, they always have enough room for the extra material to squish out left or right. The solid fill will have this for the first few lines, but once they've squished out enough (the effect is cumulative), the next line has almost nowhere to go. – R.. GitHub STOP HELPING ICE Aug 11 '21 at 14:55