Incorrect scaling?

[rainwalker 0]

Hi all, new to Cura here. I created a simple model in Blender which is supposedly 0.9mm x 0.9mm x 0.9mm (attached). But when I import into Cura, it says "Auto-scaled object to 10,000% of original size" and sets the dimensions of the object to 90mm x 90mm x 90mm.

 

First question is, why does it do this?

 

After I change it to the correct values, my preview now estimates 0 minutes, 0g, and 0.00mm. I can save the gcode, but it seems like changing this object to its natural 100% dimensions has effectively erased/nullified the object in Cura.

 

Second question is, why did restoring the object to 100% dimensions seems to destroy the object?

 

Thanks for any insight you can offer!

RepairBlindsPart.stl

[gr5 2,330]

So I think you have your units confused.  1mm is about a 25th of an inch.  It's about the thickness of a quarter.  Do you really want to print something that small?  You could fit about 20 of these things into a pea.

 

If you really need to print something that small, well try checking "print thin walls" in cura.  Also make sure you print at least 5 of them at the same time as you need to let one layer cool for a few seconds so if you print 5 that will give it a few seconds to cool one part while it prints the layer of another.

 

If you are going to be printing a lot of things this small you should invest in a 0.25mm nozzle.  Or even smaller.

 

But more likely you are confused about how big 1mm is.

[Steverc1572 5]

Are you sure you are wanting to print something appox 1/2 the thickness of your filament?

 

[ceastonoh 0]

I'm curious as to what the answer would be should the object be much larger. The answers seemed to dwell on the fact that perhaps the OP had scaling mixed up, thus no answer was offered. I have tried to import objects from a repository I have access to. Different authors but all legitimate objects than can be and have been printed. Some proceed normally through the process. Others get this 10000% dead end. Thanks for any clues to get past this.

 

[gr5 2,330]

Some CAD programs export in inches instead of mm.  Even if you are designing in mm or cm, the CAD program may be setup to output in mm when saving the STL file.  STL files don't have a way to store what the units are so cura just guesses that it's always mm as 99.9% of the time that is correct.  And all of these CAD programs have an option to choose various units when exporting to STL.

 

Anyway, often these parts that were in inches are too small to print so it appears that cura just scales them up.  10000% seems excessive.  Ideally it should scale them up by 2540%.  I suspect the cura programmers added this because too many people couldn't even see their part so this way they at least get to see that the part has been loaded.  Just a guess.

[tinkergnome 929]

29 minutes ago, gr5 said:

Anyway, often these parts that were in inches are too small to print so it appears that cura just scales them up.

 

BTW: automatic scaling is an option and can be disabled

 

From memory:

"Preferences" -> "Opening and saving files" -> "Scale extremely small models"

 

[ceastonoh 0]

OK, I'm pretty happy with the guidance so far. I made a simple shape and learned a lot just from the process. But try as I might, I can't figure out how to resize something. On the workplane it's 12 mm which is what I want but the print comes out 36 mm. Since that's a 3x ratio I figure it's got something to do with that. But I don't know what. 

Also, I am trying to make a taxicab rooflight in 1:48 scale. In tinkercad is there any way to take a basic box and turn it into a trapezoid shape? Or do I simply need to learn more? (probably option 2! Haha)

[gr5 2,330]

Watch some tinkercad videos on youtube.  I learned so much!  In 1 minute I typically learn 3 critical features or ways of thinking.

 

To make a box into a trapezoid you tilt another box and subtract.  Lots of subtracting in tinkercad - that's one of the few critical tools.

 

Regarding scaling - in cura you can just click on a part and click the scale tool on left side and then scale it up or down by percentage or absolute numbers.

 

In tinkercad every dimensions should be entered numerically (type the length of the trapezoid base for example) to get precise distances.

[gr5 2,330]

17 hours ago, ceastonoh said:

On the workplane it's 12 mm which is what I want but the print comes out 36 mm.

I never had this problem in tinkercad so I'm not sure what you are doing wrong but when you export to STL there are some options.

[djjoma 0]

I feel sorry for my English, I'm Spanish.
Export in . OBJ and your problems are solved. .STL is a format that has no measurement content, and cura tries to mitigate it with scaling (it doesn't do it all bad...).
. OBJ does contain information on the measurements used and you can open it without problems with cura.
Greetings.

[Slashee_the_Cow 619]

30 minutes ago, djjoma said:

I feel sorry for my English, I'm Spanish.
Export in . OBJ and your problems are solved. .STL is a format that has no measurement content, and cura tries to mitigate it with scaling (it doesn't do it all bad...).
. OBJ does contain information on the measurements used and you can open it without problems with cura.
Greetings.

STL is considered the (at least informal) standard format for 3D printing. It is almost always used in a scale of 1 unit = 1 millimetre, it's when you create it with a different unit scale that causes problems. Pretty much all CAD software works in mm (at least by default) and exports at that scale.