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LeonardoWL
(@leonardowl)
Member
Bad support generation

Hello,

I am slicing a case that only needs a small amount of supports, but PrusaSlicer is generating a lot of unnecessary supports. I tried changing the pattern spacing to 0.8, which helped avoid some of the unnecessary supports on the bed, but it also created some artifacts.

Is there any workaround for this? To me, it seems like a bug in the slicing algorithm. The object has a simple geometry, so the slicer should have gotten it right on the first try.

Thanks all!

Best Answer by Neophyl:

Not surprised, you have grid selected for support type.  Grid is probably the last option you want for support.   Its the original and old method, snug was added later to stop it expanding out so much along with some other improvements and organic was added most recently.  Organic is best for models like figures etc, snug generally works great on technical things. 
Your settings are also sub-optimal and will make removal harder.   I have modified your support settings and tidied up the painted enforcers (you missed a section on one side) and the bolt holes will bridge fine and so don't need support.

Try the attached updated project file.

 
Also I agree with Diem, Mediafire is bloody annoying, please don't use it for hosting files here, just attach them directly after zipping them up.
This topic was modified 4 months ago by LeonardoWL
Posted : 30/10/2023 8:21 am
Diem
 Diem
(@diem)
Illustrious Member

You seem to have a lot of unsupported overhangs, your best alternative would be to incorporate custom support in your original CAD.  Otherwise the PS support painting function (button at left) may help.

Generally, if you need help with a particular file, save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

Posted : 30/10/2023 10:58 am
fuchsr
(@fuchsr)
Famed Member
RE: Bad support generation

Unless is a simple model geometry, you're almost always better off using paint-on supports.

Posted : 30/10/2023 11:05 am
LeonardoWL
(@leonardowl)
Member
Topic starter answered:
RE: Bad support generation

Thank you,

Yes I have use the support painting function. 

Posted by: @diem

You seem to have a lot of unsupported overhangs, your best alternative would be to incorporate custom support in your original CAD.  Otherwise the PS support painting function (button at left) may help.

Generally, if you need help with a particular file, save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

The file is available here https://www.mediafire.com/file
Thank you in advance for your help.

Posted : 01/11/2023 7:26 pm
Diem
 Diem
(@diem)
Illustrious Member

Mediafire won't play, perhaps because I don't have an account and rejected all cookies...?

Use Attach file (at bottom) next time - but no need now as your rendered image above shows enough.  You have almost answered your own question. Those slots and the neat step at top and bottom all have horizontal overhangs and some don't have room for autogenerated support in the available space, the screw tunnels are likely to give trouble too:

BUT

Rotated to the position in your render above all of those problems go away - though a couple of new ones will arise.  In that position the radiused corners will print roughly even with support, so replace the awkward curves with 45 degree chamfers, at least externally, and it should print OK without any support at all.

Cheerio,

Posted : 01/11/2023 9:12 pm
Neophyl
(@neophyl)
Illustrious Member
RE:

Not surprised, you have grid selected for support type.  Grid is probably the last option you want for support.   Its the original and old method, snug was added later to stop it expanding out so much along with some other improvements and organic was added most recently.  Organic is best for models like figures etc, snug generally works great on technical things. 
Your settings are also sub-optimal and will make removal harder.   I have modified your support settings and tidied up the painted enforcers (you missed a section on one side) and the bolt holes will bridge fine and so don't need support.

Try the attached updated project file.

 
Also I agree with Diem, Mediafire is bloody annoying, please don't use it for hosting files here, just attach them directly after zipping them up.
Posted : 01/11/2023 9:22 pm
_KaszpiR_
(@_kaszpir_)
Reputable Member
RE: Bad support generation

Why not just rotate the model on the plate so that major flat surface is directly on the bed and then the shorter elements are pointed upwards?

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 01/11/2023 10:35 pm
Thejiral
(@thejiral)
Noble Member
RE: Bad support generation
Posted by: @_kaszpir_

Why not just rotate the model on the plate so that major flat surface is directly on the bed and then the shorter elements are pointed upwards?

From a structural perspective, the original orientation is better suited. Not only will the curve print poorly when rotated like you suggested but also the cover will be much weaker as the print will depend much more on interlayer-adhesion in the most critical areas. Only the lower Mountingholes would need support then. 

I would retain the original orientation. Neophyl suggestsions are good ones. 
If I were to design the above part, I would consider designing the outcropping parts as steep overhang (maybe 75%). That should retain the function of the slids while printing well without supports. 

Mk3s MMU2s, Voron 0.1, Voron 2.4

Posted : 02/11/2023 10:22 am
LeonardoWL
(@leonardowl)
Member
Topic starter answered:
RE: Bad support generation

 

Posted by: @diem

Mediafire won't play, perhaps because I don't have an account and rejected all cookies...?

Use Attach file (at bottom) next time - but no need now as your rendered image above shows enough.  You have almost answered your own question. Those slots and the neat step at top and bottom all have horizontal overhangs and some don't have room for autogenerated support in the available space, the screw tunnels are likely to give trouble too:

BUT

Rotated to the position in your render above all of those problems go away - though a couple of new ones will arise.  In that position the radiused corners will print roughly even with support, so replace the awkward curves with 45 degree chamfers, at least externally, and it should print OK without any support at all.

Cheerio,

I apologize for the inconvenience caused by my error in uploading the project. As a result, I have decided to use Mediafire instead. Unfortunately, I cannot print the case flat on the bed due to the radiused corners required for aesthetic purposes. Attached is an image of a previous print that required extensive support, sanding, and acetone smoothing to achieve the result.
Additionally, as I am printing in ASA (with an enclosure and an additional heat plate) so placing he case flat on the bed cause the walls to bend outward, which is unacceptable.

 

Posted by: @neophyl

Not surprised, you have grid selected for support type.  Grid is probably the last option you want for support.   Its the original and old method, snug was added later to stop it expanding out so much along with some other improvements and organic was added most recently.  Organic is best for models like figures etc, snug generally works great on technical things. 
Your settings are also sub-optimal and will make removal harder.   I have modified your support settings and tidied up the painted enforcers (you missed a section on one side) and the bolt holes will bridge fine and so don't need support.

Try the attached updated project file.

 
Also I agree with Diem, Mediafire is bloody annoying, please don't use it for hosting files here, just attach them directly after zipping them up.

Thank you for your suggestions, which I will take into account and remember for future reference. I plan to print the case tomorrow

Side note: the final project will be open-source and published on GitHub.
Thank you all!

Posted : 04/11/2023 12:30 am
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