large print not sticking

[Rockface]

Hi does anyone know what is causing this.
The dimensions are 200mm x 200mm
I have a glass bed set to 65C and the extruder is at 190C
Everything was calibrated recently. (it did this before and after calibration)
The bed is level.
The glass bed is secured with double sided tape instead of clips but it did this when I used clips so I don't think that is the issue
ender 3 v2 SE

The printer works fine on prints where the footprint is smaller.

I am currently unable to insert an img ??
I tried

[img]path to file[/img]

and nothing happened

 

[Cyber-Mav]

need pics

 

[ScoobyDoo]

Any Pics?

 

[VeNT]

you have to host the image somewhere. use a brim.

 

[Bug One]

I did some large prints creating my solar panel mounts. On my early prints, the large flat bases would ripple from not adhering properly.

To fix it, I had to get the z level bang on, over extrude the first layer by 10% and do it really slow.

This was PETG though.

 

[Conan257]

Obviously there are many factors involved... But my not-sticking issue recently was solved by not cooling the part down as quickly. The upper layers were cooling too fast (cold/draughty house) which would curl the bottom layer off the bed.

Warmed up the room the printer was in, turned down the part cooling fan, and I get better prints.

 

[kPATm]

Large prints need a dialed in Z offset and some bed adhesion. I used part water part sugar and put it in the microwave for a few seconds until the water disolves then "paint" it on the bed. It worked very well. I recently bought some 3dLac as I got fed up brushing on the DIY solution and the 3dLac works surprisingly well also

 

[Rockface]

I did some large prints creating my solar panel mounts. On my early prints, the large flat bases would ripple from not adhering properly.

To fix it, I had to get the z level bang on, over extrude the first layer by 10% and do it really slow.

This was PETG though.

Thanks. I appreciate lack of pics doesn't help. Not sure why I can't upload pics but your description sounds exactly like what mine is doing. I'll give it a try.

 

[Rockface]

just out of curiosity, the instructions say set the bed to 50C but if I'm using glass that is stuck with thin double sided tape does it need to be hotter ?

 

[Griffo]

Did you mention what material you're using? Apologies if I missed it.

 

[Bug One]

just out of curiosity, the instructions say set the bed to 50C but if I'm using glass that is stuck with thin double sided tape does it need to be hotter ?

I doubt the surface of the glass is the same temperature as the heater below it is reading.
I set it to 60c for PLA and 82 for PETG.

 

[VeNT]

I doubt the surface of the glass is the same temperature as the heater below it is reading.
I set it to 60c for PLA and 82 for PETG.

you'll want to leave it to "soak" for a bit at temp, or just set the first layer to be hotter.

 

[Rockface]

PLA. I don’t think it’s related to the bed. I’ve just redone the print with a raft which stuck perfectly. The base layer of the object then did exactly the same thing. I’m wondering if it’s a fan issue. I’ll tinker some more with settings tomorrow when the girlfriends patience meter has refilled.

 

[Bug One]

I think Conan may have been right, and this is to do with the print shrinking when cooling.

Slow it right down and turn off print cooling for the first few layers.

 

[Conan257]

I think Conan may have been right, and this is to do with the print shrinking when cooling.

Slow it right down and turn off print cooling for the first few layers.

I'm always right, except when the wife is involved in which case I'm always wrong....

I've had zero failures since I went down this route, albet on a Bambu A1 (which I feel is more reliable than some older printers). Clean bed thoroughly, ensure room isn't too cold (above 10C seems to be fine), reduced part cooling fan to 40% (default was 60-80%). I've had no prints "peel" since I did this, so have to believe that the part cooling too quickly was the issue.... Worth noting that print size was irrelevant, I had previously had a thought that the "revisit" time of each successive layer was an issue if it was too long between layers.

 

[aeronic]

just out of curiosity, the instructions say set the bed to 50C but if I'm using glass that is stuck with thin double sided tape does it need to be hotter ?

Can you measure the actual surface temperature of the bed

 

[Zaf]

It’s bit of a cheat and most people role their eyes at it but, I would highly recommend using DimaFix - Fixative Spray. After using this all my layer adhesion issues on big prints went away. An alternative method is to do a zig-zag of glue stick across the build plate and then use some IPA on tissue paper to rub it in creating a thin layer across the build area