S3D Strange Slicing

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roberts
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S3D Strange Slicing

Post by roberts » Wed Apr 16, 2014 3:57 am

So I was trying to print the Super Filament Path http://www.thingiverse.com/thing:267137 using S3D. I didnt notice it until I was printing that S3D "skipped" a couple slices (or created weird ones) which showed in the preview and in the actual print. In playing around I flipped the piece 180degrees and sliced again and the problem went away. I tried a few different settings but whenever I slice it face down a couple slices in the middle are messed up. If you actually look at the layer that's weird there is something there that appears to be a layer in the holes that doesnt exist in the model or in the print, just the preview. Ideas? First picture is "face up" which sliced correctly. Second one using the same settings but "face down' has two odd layers. Third picture shows one of the odd layers. There is no perimeter or fill, just a phantom layer in the holes where there should be nothing.
Correct slice.jpg
Correct slice.jpg (211.65 KiB) Viewed 6133 times
incorrect slice.jpg
incorrect slice.jpg (190.65 KiB) Viewed 6133 times
incorrect slice2.jpg
incorrect slice2.jpg (236.24 KiB) Viewed 6133 times

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jimc
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Re: S3D Strange Slicing

Post by jimc » Wed Apr 16, 2014 4:10 am

that kind of thing happens when there is a problem with the model. a few of us here have printed this and never said anything so i find that surprising not to mention silvers seems pretty thorough and would be on top of mesh errors. i downloaded the stl and i ran it through netfabb and it looks fine. he has a bunch of different files there for download. which one is it? actually can you post the actual stl here so i can take a look. under the advanced tab in slicing behavior, heal should be checked and merge should be unchecked. is that right?

another thought....put that stl your using in the trash and download the file again, slice it and see if you get the same thing.

jsc
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Re: S3D Strange Slicing

Post by jsc » Wed Apr 16, 2014 4:38 am

Check out the last section of my unofficial guide, which mentions this: http://jinschoi.github.io/simplify3d-docs/

Short story, S3D sometimes has issues with model geometry that aren't actual mesh errors. Rsilvers' model was done in solidworks from scratch, and is manifold. I have encountered the same weird slicing issue myself. The workaround is to try to move the layer interface away from the problem geometry areas. The easiest way to do this is to change the first layer height percentage, so if you have it set to 100, try 99 or 101.

jsc
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Re: S3D Strange Slicing

Post by jsc » Wed Apr 16, 2014 4:41 am

As an aside, looking at your supports, I like to manually add supports to fully support any overhanging arcs and hit all the corners on straight overhangs. The new extend support parameter in 2.1.0 may obviate the need, if you use it.

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jimc
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Re: S3D Strange Slicing

Post by jimc » Wed Apr 16, 2014 5:00 am

thats a strange issue jin. i have only seen that when there are mesh errors. never with anything else. do you know what exactly it is about it that causes that?

jsc
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Re: S3D Strange Slicing

Post by jsc » Wed Apr 16, 2014 5:09 am

Nope. Clayton said in an email:
Unfortunately, there are a lot more possible errors with STL files than just manifold edges (but that's one of the most common ones!). The software can check for some of these, but there are still others that will pass all tests yet still cause problems later on.

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jimc
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Re: S3D Strange Slicing

Post by jimc » Wed Apr 16, 2014 5:14 am

huh, good info! thanks

roberts
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Re: S3D Strange Slicing

Post by roberts » Wed Apr 16, 2014 12:00 pm

jimc wrote:that kind of thing happens when there is a problem with the model. a few of us here have printed this and never said anything so i find that surprising not to mention silvers seems pretty thorough and would be on top of mesh errors. i downloaded the stl and i ran it through netfabb and it looks fine. he has a bunch of different files there for download. which one is it? actually can you post the actual stl here so i can take a look. under the advanced tab in slicing behavior, heal should be checked and merge should be unchecked. is that right?

another thought....put that stl your using in the trash and download the file again, slice it and see if you get the same thing.
That was part 1 of the key jim. I did not have the "heal" box checked (I think it was before I upgraded to 2.1). That issue goes away when that is checked. Funny thing though is that I did run this through Netfabb previously and there were a few very minors issues that I repaired none in that area though. This was the repaired file. Nonetheless S3D found something it still didnt like and I guess discarded it and messed with those layers. However it looks like it created a new problem, it then filled the holes in on layer 63...

Then part 2 of the key came into play from jsc:
Short story, S3D sometimes has issues with model geometry that aren't actual mesh errors. Rsilvers' model was done in solidworks from scratch, and is manifold. I have encountered the same weird slicing issue myself. The workaround is to try to move the layer interface away from the problem geometry areas. The easiest way to do this is to change the first layer height percentage, so if you have it set to 100, try 99 or 101.
After changing my first layer to 110% that additional problem went away.

I'll play with that extend support feature as well, I printed more than half of the piece and it seemed OK other than those layer problems but thats probably good advice.

Thanks a bunch guys for the assist, good tips, really appreciate it.

roberts
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Location: Miami, FL

Re: S3D Strange Slicing

Post by roberts » Wed Apr 16, 2014 2:37 pm

Spoke a little too soon. I printed the part and it did print a single layer over the holes about 60% into the print. I think I'll be able to clean it out and make the part usable but I'm going to mess with it some more to get to the bottom of it. The bad/missing layers issue was resolved however by using the "heal" check box. Printed this with 110% first layer.
bad layer.jpg
bad layer.jpg (167.07 KiB) Viewed 6109 times

roberts
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Re: S3D Strange Slicing

Post by roberts » Wed Apr 16, 2014 3:00 pm

A side note, the filament hole in the part is a tad snug (maybe supposed to be?) but the filament does go through. I measured the part vs the model size and its 19.88mm vs. 20.002mm so there is a very slight shrinkage in the printed part. Not sure if thats enough to make the filament hole snug but I'll adjust a few things and see if I can get closer.

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