PETG on a PEI printbed (Lulzbot Mini)


I’ve got heavy problems with my PETG, printing on a PEI printbed (Lulzbot Mini): as I tried to pull off my print, I needed to use force. This ended in a destroyed PEI-sheet…
I use PETG from RepRapWorld (brand is REAL).
My former settings: 240° C, printbed 90° C.

As my printbed is destroyed only in the middle of the bed, I have 4 more efforts, to test other settings.
Should I use hairspray on the PEI? Or UHU glue-stick, to NOT GLUE the filament? Printing without heated bed was not successful: the object did not stick on the bed.

So - what are the best settings? Temperature and layer? Although the MINI has a self-levelling printerhead, I have the feeling, that the nozzle touches the bed - other to ABS and PLA…

I would appreciate any kind of help!!!

I have printed PETG on my Mini a few times without issue. You might need to add a little positive Z offset in your slicer so the PETG is not squished onto the PEI quite as much, reducing the stick. That is where I would start.

Also, reducing the temp of the bed might help. I have been printing the PETG with PLA settings except for the nozzle temperature. I also slowed the print down a little from the PLA profile.

Thanks for your quick reply!
I reduced the temperature of the bed down to 50° C.
But as you said: the filament is really squished onto the PEI.
Where do I set the positive Z offset in CURA???

Look under the “Machine” settings in Cura to find the Z-offset.

If the surfaces touching the bed seem to be flaring out, then there may be a problem with the auto-level. Change the wiper pad, clean the nozzle and touch points with the appropriate solvents.

There are no problems with ABS; therefore I don’t think, it’s a general Z-offset problem. Only with PETG this problem appears…

Some filaments are more prone to sticking when “squished” down. ABS is prone to coming off the build plate if you don’t squish it, and the defaults for the Mini are conservative so you get squish. This is great for new users to ABS/HIPS. It sucks for PETG. Increase the Z-Offset for PETG and it will still stick fine, but come off without so much force. All the plastic types are a bit different and you have to adjust to them.

So you’re right that it’s not a general problem. It’s just that every plastic is different. I’ve done a couple rolls of PETG now, and it’s great, but if I forget and use the standard Z-offset, it’s a pain to remove the parts.

With this answer I feel optimistic, that PETG and I will be friends - at some time… :wink:
In the meantime I used some different settings (including Z-offset 0,2 mm); so far I’m not yet happy - but at least I could remove one object without destroying my PEI further…

I am using Esun PETG and had delamination from the the PEI and warping issues on the borders. Ruined a few prints despite using brims to 20+.
This occurred at bed temps of 60, 70, 80 C, printing slow, with 240 nozzle temp.
Z offset was laying down a good squished first layer.
I sanded the PEI with 240 grit very very lightly and now I have at least twice the adhesion.

I would like to add to the discussion. Here are my print setting that result in the nicest PETG prints although it takes a long time. I would like to shorten it up some. Here is my CURA profile for my TAZ 5 for Esun PETG
Any recommendations or improvements would be highly appreciated!

Is there an expanded set of community verified Cura profiles other than the official AO hosted ones? I haven’t found a good collection.
Again, I’m a novice relative to to many here.

layer_height = .35
wall_thickness = 3
retraction_enable = True
solid_layer_thickness = 3
fill_density = 50
perimeter_before_infill = True
nozzle_size = .5
print_speed = 40
print_temperature = 0
print_temperature2 = 0
print_temperature3 = 0
print_temperature4 = 0
print_temperature5 = 0
print_bed_temperature = 0
support = Everywhere
platform_adhesion = Brim
support_dual_extrusion = Second extruder
wipe_tower = True
wipe_tower_volume = 15
ooze_shield = False
filament_diameter = 2.91
filament_diameter2 = 2.89
filament_diameter3 = 0
filament_diameter4 = 0
filament_diameter5 = 0
filament_flow = 100.0
retraction_speed = 10
retraction_amount = 1
retraction_dual_amount = 25
retraction_min_travel = 1.5
retraction_combing = All
retraction_minimal_extrusion = 0.02
retraction_hop = 0
bottom_thickness = .425
layer0_width_factor = 200
object_sink = 0
overlap_dual = 0
travel_speed = 160
bottom_layer_speed = 10
infill_speed = 20
solidarea_speed = 10
inset0_speed = 18
insetx_speed = 18
cool_min_layer_time = 45
fan_enabled = False
skirt_line_count = 2
skirt_gap = 6
skirt_minimal_length = 0
fan_full_height = .5
fan_speed = 40
fan_speed_max = 60
cool_min_feedrate = 7
cool_head_lift = False
solid_top = True
solid_bottom = True
fill_overlap = 10
support_type = Grid
support_angle = 45
support_fill_rate = 17
support_xy_distance = 0
support_z_distance = 0
spiralize = False
simple_mode = False
brim_line_count = 15
raft_margin = 3
raft_line_spacing = 1.0
raft_base_thickness = .5
raft_base_linewidth = 0.7
raft_interface_thickness = 0.2
raft_interface_linewidth = 0.2
raft_airgap_all = 0.0
raft_airgap = 0.22
raft_surface_layers = 2
raft_surface_thickness = 0.27
raft_surface_linewidth = 0.4
fix_horrible_union_all_type_a = False
fix_horrible_union_all_type_b = False
fix_horrible_use_open_bits = False
fix_horrible_extensive_stitching = False
plugin_config = (lp1
object_center_x = -1
object_center_y = -1
simplemodesettings =
simplemodeprofile = 2_normal
simplemodematerial = 1_pla
simplemodematerialtype = Beginner

For PETG I have always just used the defaults for ABS. But temps at Extruder 245, bed 75 and retraction (I don’t remember the number) some use the fan, I never have but my shop and porch tend to be cool. Wait till it cools down before removing off the PEI. The stuff is stringy so need to find the sweet spot for retraction.

I’m also using esun petg (various colors) without any delamination or problems removing from the PEI surface. I’m using 80 for the bed temp. See my profile on the first page (near the bottom) also I’ve set my z-offset to 0.03 but you need to use a calibration test first to find your offset.

After some difficult removal of PETT, I was really concerned about PETG sticking “too well” to the PEI. But the PETG I have used (Esun and GizmoDorks) has been a dream, sticking great during print (75C bed) and removing very easily when cooled to 50C. I think it does help to remove it “warm” (i.e., 50C) and not let it cool all the way.

If you continue to have trouble and the Z-offset recommended by others doesn’t resolve it, then either try some Esun brand or try some Glue Stick as a barrier between the PEI and PETG. (I like the Elmers Disappearing Purple Washable Glue Stick – it is what I use now as a barrier for PETT, and as an adhesive surface for Taulman910.) Goes down easily, cleans off easily with a wet cloth.

Quick question I have seen issues with stringing on the initial layer but the second a so on layers are perfect. I’m using the purple glue with print head at 245 and bed at 80. Any idea to reduce the stringing? Note I’ve got the first layer slowed to 20% of 3600mm/m.

Lower temp (I use 240c) seemed to reduce stringing a bit for me, but a larger layer height seemed to make the most difference. I had way less stringing with 0.32 layers than with 0.18 layers. A cool environment helps too. But I’m not sure there is any way to completely eliminate it.

Thanks I’ll adjust that. I’ve been printing with fans off but not sure how to turn them on for the first layer I had it at 75% for layer 1 but it never came on.

A short update:
with 0.2 mm Z-offset and 50°C ist works fine - so far I could remove every object without detroying my PEI.
The only problem I have is the print quality regarding the first 2 layers: the skirt is “empty” until short before the object is going to be printed (this is a general, not a PETG problem…), and there are some lumps on the first 2 layers, which tend to be included in the printing: at these locations the print doesn’t look very accurat. The remaining layers look very well!

The easiest fix for insufficient priming is to increase the skirt. If you’re using Cura, go to expert settings and increase the Skirt “Line count” to 2, or increase the Skirt “minimal length”. For S3D, the number of “skirt outlines” can be increased on the “Additions” tab.

Another option (which I use) is adding some code to the start script.
In Cura, look for the line that says “G1 Z2 E0 F75”, and add these two lines immediately after:
G1 Z2 E5 F75
G92 E0
Or if using S3D, add these four lines at the same place:
G1 Z2 E5 F75
G1 Z2 E4.5 F600
G1 X15 Y15 Z10 F5000
G92 E0

Both of these extrude a little “blob” of filament at the left-front corner of the bed before the skirt starts. Note that the default “end” scripts retract 5mm when the print completes, so when doing multiple prints back-to-back this simply gets the filament back where it should be. The extra lines are required in S3D because it moves “down and over” when starting the print, so without the lateral move that would push the head into the “blob” it just extruded.

Thanks a lot!
Today I will change my PEI. Maybe I will order S3D - but before spending 150 $ I have some other questions, regarding the combination LB Mini and S3D. This should better be a new post…
(copying filament profiles from CURA to S3D, auto-levelling, interrupting the auto-levelling between multiple prints…)

I am printing perfect prints using a esun petg. Using .5mm nozzle, cura settings for tglaze, and nozzlw temp of 240° (e3d v6) and pei bed temp of 50°.