Z-position away from build plate - organic supports
 
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burtronix
(@burtronix)
Reputable Member
Z-position away from build plate - organic supports

I'm looking for some advice on organic supports on irregular shaped objects (with no obvious flat side to ground the print). On the few that I've tried, Prusa Slicer forces the object to ground on the build plate. Then after printing, the organic supports near the ground point are small & dense - extremely difficult to remove & leave a rough surface. All other supports contacting the object further away from the build plate can be removed easily & leave an almost perfect surface. I'd like to try to position the whole object a few mm's above the build plate, but I can't find an option to do that. Is there a setting I need to change, or some other strategy?

Best Answer by Neophyl:

There are many threads here detailing how to place an object above the bed.  In short Prusa Slicer requires that ALL objects touch the bed at least in one part.  There are a couple of things that you can do about this requirement though.

You can add raft layers, that moves the whole object up by the number of raft layers.  However given that there is currently a bug in PS with rafts and Organic supports I don't suggest doing that. (4 or ore raft layers breaks slicing if iirc).

The workaround to raising an object off the plater is to right click your object and then use Add part.  Then just add a cube or similar.  At this point your Object now consists of 2 Parts.  You can then scale the added cube down to something very small, say 1mm big or less and then by selecting just the cube using the right hand tree you can move the cube  itself down.  By moving the cubes relative position to your main object it will move everything up to place the cube on the bed.  This way Part (the cube) of the object is touching the bed and so fulfils PS requirements that some Part must touch the bed.  

Supports will now go from the plater to the floating object as you desire.

Whatever you find to do with your hands, do with all your might!

Posted : 10/07/2023 2:11 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Z-position away from build plate - organic supports

There are many threads here detailing how to place an object above the bed.  In short Prusa Slicer requires that ALL objects touch the bed at least in one part.  There are a couple of things that you can do about this requirement though.

You can add raft layers, that moves the whole object up by the number of raft layers.  However given that there is currently a bug in PS with rafts and Organic supports I don't suggest doing that. (4 or ore raft layers breaks slicing if iirc).

The workaround to raising an object off the plater is to right click your object and then use Add part.  Then just add a cube or similar.  At this point your Object now consists of 2 Parts.  You can then scale the added cube down to something very small, say 1mm big or less and then by selecting just the cube using the right hand tree you can move the cube  itself down.  By moving the cubes relative position to your main object it will move everything up to place the cube on the bed.  This way Part (the cube) of the object is touching the bed and so fulfils PS requirements that some Part must touch the bed.  

Supports will now go from the plater to the floating object as you desire.

Posted : 10/07/2023 3:01 pm
burtronix liked
burtronix
(@burtronix)
Reputable Member
Topic starter answered:
RE: Z-position away from build plate - organic supports

Sorry to rehash something that's already been covered. I looked, but maybe didn't use the right search terms.

I thought of adding a sacrificial feature like that to the object. It seems messy, but I guess it's the best we can do.

Tree supports for resin prints don't require contact with the build plate. Why can't it be implemented for organic supports on FDM?

Posted by: @neophyl

There are many threads here detailing how to place an object above the bed.  In short Prusa Slicer requires that ALL objects touch the bed at least in one part.  There are a couple of things that you can do about this requirement though.

You can add raft layers, that moves the whole object up by the number of raft layers.  However given that there is currently a bug in PS with rafts and Organic supports I don't suggest doing that. (4 or ore raft layers breaks slicing if iirc).

The workaround to raising an object off the plater is to right click your object and then use Add part.  Then just add a cube or similar.  At this point your Object now consists of 2 Parts.  You can then scale the added cube down to something very small, say 1mm big or less and then by selecting just the cube using the right hand tree you can move the cube  itself down.  By moving the cubes relative position to your main object it will move everything up to place the cube on the bed.  This way Part (the cube) of the object is touching the bed and so fulfils PS requirements that some Part must touch the bed.  

Supports will now go from the plater to the floating object as you desire.

 

Whatever you find to do with your hands, do with all your might!

Posted : 10/07/2023 3:27 pm
burtronix
(@burtronix)
Reputable Member
Topic starter answered:
RE: Z-position away from build plate - organic supports

I also asked this on the Facebook Prusa Slicer group. There were some similar suggestions about adding a sacrificial part; I got an additional recommendation to set the sacrificial part's layers, perimeters, & infill to zero. That will save a bit of filament & print time. A photo of my reslice with the sacrificial part is attached, before I knew about setting its parameters to zero.

Whatever you find to do with your hands, do with all your might!

Posted : 11/07/2023 12:42 am
Neophyl
(@neophyl)
Illustrious Member
RE: Z-position away from build plate - organic supports

The sacrificial part can be any size, so you can make it 1mm square or less and 0.2mm high. So filament or print time is hardly a factor.  Also it can be positioned anywhere as long as it’s on the build plate.  I usually place mine either front left corner near the purge line or if I’m doing a helmet or similar I put in under where the support will go.  

Posted : 11/07/2023 4:55 am
burtronix liked
burtronix
(@burtronix)
Reputable Member
Topic starter answered:
RE: Z-position away from build plate - organic supports

I posted a remixed model on Printables & included instructions for suspending objects over the build-plate for use with Organic Supports. This is based on info I got here. Let me know what you think. Any recommendations, additions, or clarifications?

https://www.printables.com/model/527408-rocket-racoon-remix

Whatever you find to do with your hands, do with all your might!

Posted : 14/07/2023 9:34 pm
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