Strange default Orientation with printing issues

Using Perform 2.14 this is the second time I had this model to print orientation. It was my understanding that all models should be a angle to prevent problems at that layer. While I was thrilled with this presentation less cleanup on the outward faces, the bottom of the model cab, had problems. It looked thick and uneven, and appeared to have tear and peel up lines all the way along the second. There is a flat second on the left of the model, next to the doors. I should have not accepted this positon and moved the model manually, why did Preform present the model this way?

While the rest of the print is nominally very good this one area causes a lot of clean up. I will reprint this today with manual positioning.

This part looks like it should print fine with an orientation close to the one shown. I’d try to just add 5 to 10° on both the X and Y axii and see if there are any red zones at the top of the part after generating the supports (I bet there wont be any).

My workflow with such parts is basically to search for the maximum angle at which the part will print well, using preform warnings, and eventually go back a bit if there’s an issue with the supports.

John,
So I fixed a couple design errors, made a new STL file, and put it back into preform. This time I let it setup on its own and indeed it angled it about 15 degrees, so I left it, If it didn’t do that I wasn’t going to let it be horizontal again. Saw no red zones either. 2 more hours to go

I highly recommend against using the automatic settings, it’s not going to do as well as what you could figure out, the ability of the software to understand what the part is like is limited.

One of the print problems you have there that caused the issues is to avoid having surfaces parallel to the build plate, the reason is that layers that have large portions of unsupported surface can shred a bit during the layer separation process, so you get stuff where you get arches around where the supports touch the surface because the layer is being torn apart between them.
So for something like that, putting it at an angle allows for the model to start at a small point and each subsequent layer will be only a little bit larger than the previous layer so they won’t fall apart and you can even use fewer supports.

Zach,
I agree, I thought this default position was strange, maybe a new algorithm for positioning, I do change most of the auto positions to something where I keep the clean up to a minimum. I believe the poor results on the bottom were indeed the suction and subsequent tearing were because of the positioning. The print of last night appears to be more successful on points.

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When you first import a model, PreForm will orient it according to how it was placed in your CAD software. There is an ‘orient all’ option in the left toolbar that will have PreForm calculate the optimal orientation for you. Many users prefer to rotate their models manually, and this video is a great resource on how to go about doing that.

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