Unable to place on print bed a specific face
 

Unable to place on print bed a specific face  

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riccardo.ravicini
(@riccardo-ravicini)
New Member

I'm trying to print this object:

stl file is available here: https://drive.google.com/file/d/1F0EKq714_UO4HxabVGPf466v1UUjJz-z/view?usp=sharing

Big faces are not parallel and here is the problem: in no way I was able to say to Prusaslicer to place it on the bed on the below surface.

It always puts the bottom surface down, facing the bed, as expected, but with bed parallel to top flat surface, so leaving it "floating" and requiring unuseful supports, as it the picture (difference is not a lot, 1.5 mm on 20 cm length, but it can be seen that horizontal surface is the top one and not the one at the bottom). I know that I can also print it vertically, seated on the short side, but I'd like to know how to choose the face orientation that I want or why I can't.

Thanks,

Riccardo

Posted : 30/06/2020 8:29 am
joan.t
(@joantabb)
Veteran Member Moderator

Hi Riccardo, 

there are overhangs on all surfaces,  which would make it interesting to print. 

I opened the file and Prusa Slicer placed the model on the sides of three  brackets,  I could turn it on all sides but none would sit flat, there were always protrusions on the bottom side, or overhangs

If I was printing this item I would do it like :-

I have attached a .3mf file with the support enforcers and blockers. 
printing at an angle like this will minimise the surface blemishes due to supports. 
at 45degrees the layers are pretty much self supporting, the supports are only there to stop the model falling over during printing. 

I have set the print up with PLA at 0.2mm layer height. you can change this if you require. 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 30/06/2020 4:16 pm
riccardo.ravicini
(@riccardo-ravicini)
New Member

Thanks a lot for your kind reply and help! 😊 

I'm aware that supports are required on every orientation.

I've printed 2 of them vertically, applying 5 mm brim to keep it well attached.  Final item has a very nice look and hooks should be strong, but I'll give a try to your suggestion, I need 11 of these pieces, I can do many experiments!

My question is more related to how Prusaslicer works, as I don't get why I'm unable to put it on bed laying flat on bottom long stripes.

BR,

Riccardo

Posted : 02/07/2020 11:10 am
joan.t
(@joantabb)
Veteran Member Moderator

Hi Ricardo, 

the model appears to be a tiny bit  off level... 
it appears that Prusa slicer could not adjust by the small amount needed!

try this file

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 02/07/2020 12:16 pm
Andrew
(@andrewld)
Estimable Member

I am unsure what you mean by on the long stipes. If you mean the thin ones it sat down fine for me see attached.

Andrew

Posted : 02/07/2020 12:20 pm
riccardo.ravicini
(@riccardo-ravicini)
New Member

I don't see it well from the picture, but I guess it's not ok.

Or at least, I wasn't able to really to put it laying on the bed on that side.

I'm sorry, it'd be difficult to describe it even in my mothertongue, using English doesn't help, so let me show the result with some images.

This is the piece to be printed, apparently oriented as I want it and as you did too:

I sliced it, and show you two screenshots between 0,20 mm and 2,00 mm. I did it removing supports and brim to have a clearer view.

If everything works as expected, I'd see on all those layers an image very similar, with 5 stripes always 199,9 mm long.

Instead, this is @0,60 mm (3rd layer):

And this is what I get @ 1,20 mm (6th layer):

The problem is that the face that is oriented upwards, with the wide relief, and the face oriented downwards, with 5 narrow protruding strips, are not parallel each other. This piece is 199,9 mm long, and main body at one end is 10,5 mm high, while at the other one it's 12 mm.

The piece is put with the right face downward, but bed is anyway kept parallel with the other face, the one oriented upward.

I've put comments on a lateral (left) view screenshot:

I'm sorry to be so boringly long and repetitive, but it's difficult to explain the problem.

BR,

Riccardo

Posted : 02/07/2020 11:40 pm
Andrew
(@andrewld)
Estimable Member

@riccardo-ravicini

Do not apologise for a long explanation. I for one would rather have more information than play email ping pong. 

First question, and not intended to be insulting, are the bottom strips meant to be flat? Some Cad packages are notorious for "snapping points" being selected and lines not being quite as expected.

Question 2, do they need to be thinner at the ends? Is it for technical or looks. I like a challenge but sometimes when working with wood I find using a hammer and nail is easier than creating a pretty joint.

Advice as provided by Joan is sound. Playing with the angles and supports will get you a print however if you are going to have to sand off the support marks would shaping the part done without supports be just as effective... Possibly easier?

Last thought. Try to grab the beta copy of the new slicer. In that one you can limit supports to exactly where you want them rather than pushing blocks around.... At least that's what the webcast said. 

Best of luck

Andrew 

 

Posted : 03/07/2020 7:17 am
riccardo.ravicini
(@riccardo-ravicini)
New Member

@andrewld

Yes, bottom stripes are meant to be flat, they are simple parallelepipeds with just a chamfer on long edges.

Going on with my trials, I found something else weird: the final piece of the serie is shorter than the others, just 110 mm instead of 199,9 mm.

(Only) this one is placed by Prucaslicer perfecly flat on the bed, with stripes parallel to it, as expected:

Posted : 03/07/2020 4:46 pm
Andrew
(@andrewld)
Estimable Member

The issue could be an error in the way its being interpreted or put together by the CAD package and passed to the slicer. The general rule of thumb for this sort of thing is to create a new STL or OBJ (open CAD file and save with a new name) and slice again. The CAD equivalent of IT support...."switch it off and on again". If the slicer hadn't shown the layer problem I would have gone with poor adhesion on the bed.

Again, best of luck. 

Posted : 03/07/2020 6:46 pm
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