I have a mystery Stl file that changes completely when I print it.

[roon4660]

I made a simple little lid for a box in Tinkercad which I have used quite often that looks ok in the slicer until I slice it and then it changes completely I have never had this happen before and though this tiny little print is not important to me I am just wondering what is going on. If anyone wishes to take a look at it and tell me why it does this here is the file. I did it in both Prusa and Cura with the same results. In fact as soon as you slice the stl file you see the change.

[Ender5r]

I found part of the problem: the model is not sitting flat on the build plate. It's tilted up on the left end. I tried rotating it so it is flat, but it still has issues. I would redo it. I suspect you accidentally rotated it in TC and that issue promelgated through the whole model.

[roon4660]

Aha! I knew you would find the problem. I shall do that and see what happens. It is strange though because Prusa is supposed to lay things down.

[roon4660]

I tried and tried and restarted but it is basically just the same. A bottom and no sides. I started new with a solid box and a void box which I lifted up 0.4 to make the bottom centered them on 2 axes and grouped them. As usual it looks fine when I import it to the slicer and when I slice it I only have the bottom, no sides.

[Ender5r]

Cura also has the option to "drop models to the build plate". However, if the model is off kilter from the start, that won't help. In Cura I had a bottom & 4 sides, but there was a small section completely missing from the left corner of the front edge.

Here are some images of what I got:

This shows the left end off the build plate.

This is how it sliced. Notice the front left corner.

This is after I layed as flat as I could manage.

And sliced after laying flat.

[roon4660]

I tried and tried and restarted but it is basically just the same. A bottom and no sides. I started new with a solid box and a void box which I lifted up 0.4 to make the bottom centered them on 2 axes and grouped them. As usual it looks fine when I import it to the slicer and when I slice it I only have the bottom, no sides.

[Larry]

How about this. Seems to have fixed it.

[Larry]

oops sorry didn't fix it after all my bad just flattened it and nothing else.

[Larry]

Ok i don't know what you did to that model but you did a REALLY good job of it 😁

[Ender5r]

Larry, seems you got the same result I got. It is odd for sure. I tried the Mesh tools in Cura 4.8. They made some improvement, but didn't fix the basic issue.

roon4660, if you post the specs, I'm sure 1 of us can create a working STL for you.

[roon4660]

I really don't give a damn about the stl file other than the fact that I don't know what went wrong. I was making a lid of OD 38.6 x 51.6 x 12.4 with a wall od ).4 mm. in Tinkercad. Since Tinkercad is the only thing I know how to use I would just like to know what I did wrong.

[Ender5r]

I have never used TC, so I'm no help with it.

[roon4660]

I explained further up exactly how I did it. It's always worked before for me. I'm puzzled.

[roon4660]

In trying to learn how to use Tinkercad I did lots of similar little projects but I have never had this happen. It couldn't be an easier project. I redid it from scratch 3 times with no cigar. I was just about to try a much more complicated project but until I figure out what is wrong.....hmmmm I wonder if I reboot my computer that might help. I have a habit of leaving it on all the time. I know that tinkercad can bug sometimes with a little help from my old macbook pro.

[Ender5r]

It seems pretty unlikely that a reboot would help, but what harm can it do?