Moving Models In the Z-Direction
 

Moving Models In the Z-Direction  

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Jason’s MMU
(@jasons-mmu)
Active Member

I am working on some SLA prints but the operation is the same for FFF printers too.

I have some downloaded figurines that have no base. When I try to print them, only a small fraction of one foot is laying on the ground/platen. This is a result of the feet not being quite flat. What I'd like to do is move the model downwards by a small amount, say 0.1mm to give a greater contact area.

When I try to do this, the slicer automatically resets to the point where the model just touches the platen. Is there a method of locking the model z-position to what I need. I can add a raft and supports but that adds to the material used and also makes the resulting feet/shoes even less flat when printed.

(I can't modify the models as they are)

Many thanks

J

 

 

 

 

Posted : 25/11/2020 2:45 pm
Neophyl
(@neophyl)
Noble Member

No. In normal use you can not adjust a single model in the z. It always places the model on the bed.  There are ways around that to move parts up which is the usual complaint about z in slicer, but in your case you want to move it down. That is easy and the correct process in Prusa Slicer/Slic3r etc is to use the cut function. It’s located on the left toolbar of the plater. Cut off the bottom and the model will drop to the plate. Choose keep top and you can discard the lower. 
https://help.prusa3d.com/en/category/left-toolbar_210

This post was modified 2 months ago by Neophyl
Posted : 25/11/2020 4:45 pm
shags72 liked
Jason’s MMU
(@jasons-mmu)
Active Member

Great, I’ll give it a try.

 

thanks!

 

J

Posted : 25/11/2020 5:00 pm
JPG_master
(@jpg_master)
Active Member

@neophyl

Hi,

is there any way to STACK e.g. the previously cut horizontal slizes?

Reason: I found an STL i want to print in diff colors where e.g. on color covers a set of layers or mm's hight.

So i did cut and always kept both parts: upper and lower.

Now I want to rearange them on top of each other, but the Z values always jumps back to the original.

thanks

Posted : 25/11/2020 9:19 pm
Neophyl
(@neophyl)
Noble Member

@jpg_master

Yes there is.  There have been many many complaints over on github about slicer not allow the basic things of moving a part upwards.  However the whole slicer workflow and logic is fundamentally different.  However you can still do it, you just have to work within the limitations of that flow.

The primary rule is that some part of your Object HAS to touch the build plate (or a raft but technically that's still touching the plate via the raft).   When you think about it this is logical as to print some part of your model does actually have to be on the bed. 
However an Object can be made of multiple Parts.  So the trick is to place AN object on the plate as usual.  That can be anything, from a simple cube imported or the base layer of the thing you want to stack.  Once that part is on the bed you right click the object and select Add Part.  Then select the stl file of the thing you want to stack or move off the build plate.  That second object can be freely positioned wherever you like.  Even midair where it will fail to print without supports if you really want to make plastic spaghetti.  That's because part of the Object is still touching the build plate so fulfills the primary rule.  You can add as many parts to an existing object as you like.

To select a part you cant click it on the build plate as that selects the whole object but you can select it via the Object manipulation panel (the section on the right hand side).  Select it there and then you can use move, scale, rotate etc on that part to position it.

The other thing you have to watch out for with the current version of slicer is it will complain if there are empty layers and not slice.  So stacking objects on top of each other where they don't touch is currently not allowed.  The new 2.3 versions currently in alpha have a checkbox to disable that warning.  There's ways around that too though, you can add a part modifier that is basically a very tiny 0.5mm bit between the objects and that way the layer is not empty.  That way its still easy to separate them.  
We had a lot of this when printing PPE in the early days of the pandemic.  People were trying to stack visor frames so all the workarounds became more widely known.  I think it was that behind why the ignore empty layers option has been added in.

If I haven't explained that well lmk and I'll put together an example project sometime tomorrow.  For now sleep beckons 🙂

Posted : 25/11/2020 11:58 pm
JPG_master
(@jpg_master)
Active Member

@neophyl

Hi,

everything you did explain is absolutely logical ... and it works on the screen.

I need a little more practice and go back to the start.
The story is:
Want to print a logo of Soocer Club Bayern in Germany. It needs 3 colors, but the designer did put in twor areas that are concentric but different color compared to outer ring.
So I did try to cut it in model-layers ( each multiple print layers ) according to color AND seperate the inner piece in that one concentric part from the others.
The Idea is to "restack" them ( without the weird inner part in diff color) and manage then the print layer colors.
Only the inner part than would require a separate print and then ( sorry ) glueing it in.

As the color layers in the model have like 3mm, I do not think, I can print a concentric ring and disc of that height one after the other with different filament / color.

that is why the exercise 

 

thanks a lot for your advice and have a good night and weekend.

Posted : 28/11/2020 8:08 pm
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