Exporting to stl and 3mf file formats

I am new to 3D design and the use of cad programs. Fifty years ago I was a draftsman for an architectural metals firm. I was very good at creating working drawings with pencil, ink and a drafting machine. Fast forward fifty years and I am really struggling to learn cad and 3D design for 3D printing. I have tried multiple applications and keep coming back to Shapr3D.

To my question and I have researched this on the forum and find other have had the same issue in the past. Once I design an item, then export and reimport it to my 3D printer slicer, the model has increased 10 times. I am using Bambu printer and their slicer. I found reading through here is that you should be using the 3mf file format. However when I use that format the model still comes out oversized. This does not happen on the other programs like Onshape. Am I doing something wrong? I hope someone can enlighten me.



It’s possible the slicer isn’t paying attention to the units information embedded in the 3MF file. What units of measurement are you using in Shapr?

I’m certainly no expert, but if it is exactly 10 times bigger, I would immediately suspect that the source is in millimeters and the destination is interpreting it as centimeters.

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Agree with @TheBum (your slicer does not read the unit, other slicers do) and @Steve : just select a unit 10 times bigger in Shaper before exporting in 3mf and the body should be of the correct size on the slicer.

I’ve checked that the 3mf file generated by Shapr3D contains the unit informations which are selected in the unit menu of Shapr3D.

For the curious ones, just export a .3mf file, replace the .3mf extension by .zip as it is actually a zip file, unzip and navigate into the folder to find the 3dmodel.model file, which is a .xml file you can open in any text editor, and you will get something like:

<?xml version="1.0" encoding="utf-8"?>
<model xmlns="http://schemas.microsoft.com/3dmanufacturing/core/2015/02" unit="millimeter" xml:lang="en-US" 

The unit of the xml file copy the unit selected in the unit menu of Shapr3D



I’m a was a worker bee (mostly) for builders 20 years ago. Tilt-ups, hotels, custom homes etc. Carpenter, pipe fitter, heavy equip etc.

If you can, it’s best to start thinking in metric in today’s 3d world of design. America should have adopted it long ago. I still catch myself thinking in inches but I have gotten better at the rough conversions in my head.

To quickly convert I use a simple mnemonic in my head: 1 in to aprox. 25mm. That helps a lot to quickly flesh projects out in mm and start thinking in mm. 4 inches is roughly 100 and therefore a foot is close enough to 300mm. You might try it unless you are bound to SAE for some reason or other.

All slicers for 3d printers work with mm. Some are smart enough to see you need conversion and ask you if you want to.

Change can be hard.


Thanks for all of the suggestions. I am doing a copy of a phone stand measuring everything with a caliber in metric, see screenshot. Both the Bambu Slicer and Shapr3d are set to mm. I will play with the settings and see if I can somehow import exactly like I have designed. On non precise models I can just reduce the size in the slicer but when I do this with something more precise the printed model does not match the design.

Bambu “should” convert 3MF files to mm for you. Prusa slicer does. I believe both are based on Slic3r. I could be wrong though. I don’t export Stl anymore. 3MF is superior.

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I was born in metric world and always in shock how you people live with these inches :laughing:

Of course I know how to covert (using 25mm formula too for quick result) but still.

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Just to clarify, I have exported stl files that I have designed from TinkerCad and OnShape, two other popular design applications. When importing to the Bambu Labs slicer this resizing does not occur. I am obviously missing something in Shapr3D.

Steve got it right. I imported the stl file into Tinkercad and it was interpreted as Centimeters…

Thanks everyone. I will start paying more attention and use the 3mf format.