Beginning of layer build up on spiral model

Hey all,

Printed a spiral vase and when it was printing, looked great and was really happy. When I took it off the heated bed, I noticed at the back of vase was a build up where the layer started and stopped. I thought at first it was a cooling issue but maybe its actually a retraction issue? I didn't see any stringing when it was printing but not sure what it can be? Looks like extra build up - some I can cut off but also looks like it hasn't set well. Just at the back down the seam. Everywhere else on the vase looks perfect! Here is a pic:

Attachment 16532

This is printed with an Ender 3 v2, treated glass bed, PETG, 240'c nozzle, 80'c bed, 0.4mm thickness, 2 layer wall thickness, 0 cooling initial layer and up to 50% cooling by layer 6.

Any ideas on what this could be? Any settings I can try to remove this? I thought maybe trying the randomised starting layer position (is that a thing?).

Many thanks in advance!

Ben

Did you print it with any supports? I can’t tell based on the angle, but when you have a problem in back of the model, the first thing that comes to mind would be the seams (which you identified). Cura slices models such that the seams are located on the back face. If you don’t have any supports and the layer sags, it could produce what I believe I’m looking at. Have you printed any calibration models to make sure everything is suppose to do what it’s suppose to?

Something like this:
https://www.thingiverse.com/thing:2656594

Hey AsianGuy, thanks for coming back to me.

No I didn't print with supports and the rest of the print is perfect, just this back seem, so not sure if that would help do you think? Or would it? The model creator said no supports so was following that.

Will try one of the calibration models now. I have printed a Benchy when I first got the printer but that was with PLA so maybe I should try again with the PETG I am now using.

Thanks again!

Ben

I did as you recommended and printed a calibration print. Came out well except for the same stringing bits. See off the side of the numbers I have a build up which looks to be the same as on the vase. On this though, I can cut these off and no one would know better. On the vase, they are sticking to the curved parts and then impossible to remove.

Attachment 16536

Is this just stringing clumping together or does this look to be something else (hoping more experienced 3D printers will know what this is)? I am currently printing something else and have changed my retraction settings to retract a bit faster and a bit further to see if that helps. Also dropped my temp to 235'c to see if that helps with the strining too.

Any additional insights from anyone would be helpful!

Thanks again :)

Ben

the original issue is just a 'z seam' .
enable random start for all layers to get rid of that.

what material are you printing with and what machine ?

Also there is a thing called 'wiping' if you enable retraction while wiping it reduces stringing and blobblign due to retractions.

But different machiens have different retractions requirements.
Also different slicers have different settings.

so the more info you give, the more we can probably help :-)