andyelder
Posts: 7
Joined: Sun Aug 07, 2016 4:53 pm

Small voids/blobs in external perimeters at layer change

Wed Aug 09, 2017 1:26 pm

Hi all,

I'm using a Prusa i3 MK2S, and I'm dialing in my settings. I've been changing several different variables, in order to try to get rid of some surface defects (see the hull on my 3D Benchy below):
IMG_1572.JPG
Here's what I think is happening. The printer completes the outline, pauses for a split second, and then raises up to the next z-height, and starts printing again. I've tried changing several settings, and nothing seems to make a difference. I've tried messing with coasting, negative extra restart distances, force retraction. Is there anything obvious that I'm missing?

I know that I can usually hide these issue in a corner, or on the back side of the part, but I would really like to get this fixed. My Printrbot Simple Metal doesn't produce these artifacts, so I know something off on my Prusa.

Thanks in advance!

gregspruce
Posts: 9
Joined: Mon Jul 24, 2017 8:34 pm

Re: Small voids/blobs in external perimeters at layer change

Thu Aug 10, 2017 10:57 am

I think your and my issues might be related: viewtopic.php?f=9&t=7971

So far, the only luck I've had to get rid of this is to switch to Slic3r PE...

Vexelius
Posts: 3
Joined: Tue Mar 29, 2016 12:48 am

Re: Small voids/blobs in external perimeters at layer change

Thu Aug 10, 2017 1:53 pm

Seems that this issue was caused by a change to the slicer algorithm in the V4.0 update.

One day before updating Simplify3D, I printed the ring that you see at the left side of the photo. At the right side, you can see a print done after the upgrade. I'm using the same settings and models. In fact, it's the same *.factory model I have used without issues for a long time.

Image

Previously, the blob was so small that it was barely noticeable. Even if you touch it, it only feels like a small "bump". After the update, the blob is enormous and extends almost 1mm outside the ring's perimeter.

andyelder
Posts: 7
Joined: Sun Aug 07, 2016 4:53 pm

Re: Small voids/blobs in external perimeters at layer change

Thu Aug 10, 2017 2:23 pm

gregspruce wrote:I think your and my issues might be related: viewtopic.php?f=9&t=7971

So far, the only luck I've had to get rid of this is to switch to Slic3r PE...
Thanks for the insight! It does look like your problem is similar to mine. I just haven't had the best of luck with Slic3r PE - it doesn't seem to handle the outline overlap on top surfaces as well as S3D does. Do you just run Slic3r PE with the stock settings?

-Andy

gregspruce
Posts: 9
Joined: Mon Jul 24, 2017 8:34 pm

Re: Small voids/blobs in external perimeters at layer change

Thu Aug 10, 2017 2:47 pm

I'll try to remember to post my current settings when I get home.

andyelder
Posts: 7
Joined: Sun Aug 07, 2016 4:53 pm

Re: Small voids/blobs in external perimeters at layer change

Thu Aug 10, 2017 2:48 pm

gregspruce wrote:I'll try to remember to post my current settings when I get home.
That would be greatly appreciated! :-)

andyelder
Posts: 7
Joined: Sun Aug 07, 2016 4:53 pm

Re: Small voids/blobs in external perimeters at layer change

Fri Aug 11, 2017 10:02 am

@gregspruce, you were absolutely correct! Here is a picture of the same 3D Benchy model, sliced with Slic3r PE, using the stock settings at 0.2 mm layer height. No retraction artifacts on the outer surface at all!

Time to start learning that program, I guess...
IMG_1576.JPG

brian442
Posts: 1243
Joined: Mon Nov 28, 2016 5:35 am

Re: Small voids/blobs in external perimeters at layer change

Fri Aug 11, 2017 11:03 am

The photo you posted at the top had all of your retractions lined up on that side of the hull. You could easily move them to a different location by adjust the start point setting. But more importantly, you still look like you need to make some adjustments to your S3D retraction settings.

The other photo you just posted doesn't have any retractions in that same area, so it isn't really a good comparison. But if you think the retractions that it are doing look better, then it would help if you posted both gcode files (one from s3d and one from slic3r). That way you could compare the retraction settings that are being used.

gregspruce
Posts: 9
Joined: Mon Jul 24, 2017 8:34 pm

Re: Small voids/blobs in external perimeters at layer change

Mon Aug 14, 2017 10:22 am

andyelder wrote:@gregspruce, you were absolutely correct! Here is a picture of the same 3D Benchy model, sliced with Slic3r PE, using the stock settings at 0.2 mm layer height. No retraction artifacts on the outer surface at all!

Time to start learning that program, I guess...
IMG_1576.JPG

I was using a custom built Chimera cartesian printer. So I didn't post those settings - this weekend I received and assembled my MK2S kit and am just using the built-in profiles.
Slic3r doesn't have this blob issue in the first place, and then on top of that, intelligently places the layer z-seams in areas that make them virtually invisible - depending on the model geometry.

Why the expensive S3D doesn't have this seam hiding feature, I can't tell you. The best S3D can do is align the seam near a specified set of coordinates. Pretty disappointing to be perfectly honest.

andyelder
Posts: 7
Joined: Sun Aug 07, 2016 4:53 pm

Re: Small voids/blobs in external perimeters at layer change

Tue Aug 15, 2017 11:07 am

brian442 wrote:The photo you posted at the top had all of your retractions lined up on that side of the hull. You could easily move them to a different location by adjust the start point setting. But more importantly, you still look like you need to make some adjustments to your S3D retraction settings.

The other photo you just posted doesn't have any retractions in that same area, so it isn't really a good comparison. But if you think the retractions that it are doing look better, then it would help if you posted both gcode files (one from s3d and one from slic3r). That way you could compare the retraction settings that are being used.
Sorry all about the late reply - had a busy weekend, and couldn't get back until now.

So I apologize, I don't think that I was clear enough. Yes, I did only show one side of my model, but there are no retraction scars anywhere on the model. I just used that one picture to show a comparison of the same side. Thanks for the offer to look at my gcode-but I don't think it's necessary now. I've changed a TON of retraction settings, and I can't find the combination that works. Maybe I'll try to go back in the future, but if I need to have better surface quality, I'm just going to use Slic3r PE. Which bums me out, but I'm selling my models, and I want them to look as good as possible. Hopefully a software update to S3D will fix this issue!

Thanks all for your help!

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