latreides
Posts: 21
Joined: Sun Apr 16, 2017 12:47 pm

S3D no longer generates supports?

Wed Nov 08, 2017 6:51 pm

S3D has always been great about supports, until recently. I am not sure if this lines up with 4.0 or if it started happening earlier than that, but its only putting a small fraction of the supports that are needed by the model.

Here is an example of a dragon in S3D. There are quite a few areas on this model that need supports that S3D is ignoring. The most obvious being the nose area.
S3DDragon.png
The same model in Cura, puts supports exactly where I would expect them.
CuraDragon.png
The site doesnt allow files over 3 MB to be uploaded, so I cannot attach the factory file, but here is the model I am trying to print: https://www.thingiverse.com/thing:1249581

Note that this happens with nearly every model I try and print that needs supports, not just the one in this example!

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dkightley
Posts: 2313
Joined: Tue Mar 10, 2015 4:09 pm

Re: S3D no longer generates supports?

Wed Nov 08, 2017 8:13 pm

Change the support pillar resolution to 1 mm.....and you'll find more appropriate support is automatically generated.

Then read this: https://www.simplify3d.com/support/arti ... tructures/

Or try reading first...then adjust the setting...... ;) ;) ;) ;) ;)
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

latreides
Posts: 21
Joined: Sun Apr 16, 2017 12:47 pm

Re: S3D no longer generates supports?

Wed Nov 08, 2017 9:23 pm

Changing the resolution made supports appear where they should be (thank you for that tip), though I do not understand why. That link has a lot of useful information, but it does not explain why a larger support resolution will make S3D ignore areas that clearly need support.

At first I thought that it just might not have room to draw supports at larger resolutions, but that doesn't seem to be the case with the above example. The nose area, when I have it on 4 mm supports, will not have any supports under it. When I change it to 2.5 mm supports, it has a 2x2 grid of supports. Clearly there is enough room under the nose for at least a single 4 mm support column.

Is there something that explains why it won't draw supports in various locations when you choose certain support resolutions?

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

Re: S3D no longer generates supports?

Thu Nov 09, 2017 3:46 am

It's explained here too:
https://www.youtube.com/watch?v=6tlrCpwAV4M

If your model has very small features that are only 1-2mm in size, you can't try to use a 4mm resolution for the supports. So if you have small features on the model you need to reduce the pillar resolution.

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dkightley
Posts: 2313
Joined: Tue Mar 10, 2015 4:09 pm

Re: S3D no longer generates supports?

Thu Nov 09, 2017 5:08 am

Changing the resolution made supports appear where they should be (thank you for that tip), though I do not understand why. That link has a lot of useful information, but it does not explain why a larger support resolution will make S3D ignore areas that clearly need support.
The support documentation doesn't explain the reason for the pillar size in the first place very well.

Basically, the bed is divided out into a mesh of the size of the pillar resolution, and when determining whether support is needed or not, each square in the mesh is looked at individually. If there is sufficient of a requirement in one of the columns in the mesh...ie above a certain amount....then it is decided that support is needed in that column...and if you were looking at the preview view when auto support is shown, then a support column will be drawn on the preview.

At this point, you need to understand that the column that shows...like in the screenshot you posted....is not of the actual support, but a preview of where support will be generated. The actual support created will follow a different set of parameters relating to density, direction of the individual layers and dense support, etc. Only when you slice the model will you see the actual support.

Hope this helps a little.....
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

latreides
Posts: 21
Joined: Sun Apr 16, 2017 12:47 pm

Re: S3D no longer generates supports?

Thu Nov 09, 2017 10:11 am

brian442 wrote:It's explained here too:
https://www.youtube.com/watch?v=6tlrCpwAV4M

If your model has very small features that are only 1-2mm in size, you can't try to use a 4mm resolution for the supports. So if you have small features on the model you need to reduce the pillar resolution.
I have watched that video, it doesn't really explain the situation. The nose is much larger than 1-2 mm (2.5 mm supports create a 2x2 support pillars under the nose).
dkightley wrote:Basically, the bed is divided out into a mesh of the size of the pillar resolution, and when determining whether support is needed or not, each square in the mesh is looked at individually. If there is sufficient of a requirement in one of the columns in the mesh...ie above a certain amount....then it is decided that support is needed in that column...and if you were looking at the preview view when auto support is shown, then a support column will be drawn on the preview..

I did find a Makers Muse video that helps explain it a little more (similar to your description) though this seems like a bug to me. 4 mm support will clearly fit under the nose (with room to spare!) and the nose clearly needs support. This seems like a no brainer.

At the very least, a warning that you are missing some crucial overhangs with your support resolution would benefit S3D. It was pretty obvious with this model, but its much less obvious on others. This could easily be accomplished by internally generating support at say, half of your given support resolution and compare that to your current resolution and if there is more than X amount of unsupported area in your current resolution (thats covered in the internal check) it should give you a little warning icon/notification.

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