Posts: 138
Joined: Wed Jul 19, 2017 9:37 am

Odd Blobs?

Wed Sep 16, 2020 12:14 pm

I've got an odd defect in my prints that I'm trying to chase down. I have a small box with some printing on the bottom (2 layers deep), and I've tuned up the retraction & restart distance to give good results on the letters Those settings weren't quite the best to minimize the groove where things start & stop for the side walls, so I set up a separate process to start on the 3rd layer to keep things tidy.

This was working OK with black eSun PLA+ filament, but I ran out of black & switched to green. That seemed to be very liquid at the same temperatures, so I back off on that, and re-tuned things a bit. The bottom of the box has a small 45 degree bevel on the edge, and I am getting large blobs where the perimeter starts, but as best I can tell, it's not on the first layer. It's acting like it's not retracting when it moves to start the 2nd layer.

I thought it might actually be from the process change when I switch at the 3rd layer, but I printed the example below with a single process, and it's actually worse. It appears to be blobbing on both the 2nd & 3rd layers, and sagging down onto the built platform.
Double Blob Test Print.jpg
Double Blob Test Print (Close Up).jpg
I'm guessing that it's something I changed in the retractions settings on the Advanced page. I've been chasing this for a couple days, and my brain is fried. I've attached my factory file in case somebody has more functioning brain cells than I can muster at the moment.

Blob Test.factory
(34.84 KiB) Downloaded 4 times

Posts: 138
Joined: Wed Jul 19, 2017 9:37 am

Re: Odd Blobs?

Wed Sep 16, 2020 10:04 pm

Update: I went off for a while & came back to this. I checked the retraction settings, and discovered "Force retraction between layers" wasn't selected. I went back & verified that the black filament version that worked fine did not have this set. I tried turning that on, and it made no difference...

Update #2: It appears to be model dependent. The test I've been running to get the text working well is only ~ 1/6th of the total area of the final box, If I print the whole bottom, I don't get the blobs. As a result, it's not critical to print this model, but I'd still love to know what is going on. I'm beginning to suspect that it may be a pathological bug in S3D.

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