Hello everyone, I printed a part with PETG which has to be 300 mm long. Now I have found out that it is only 299 mm. What do I have to change in the settings so that the part is dimensionally accurate?
Regards, Dieter
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PETG (polyethylene terephthalate glycol-modified) is a durable, lightweight filament known for its strength, flexibility, and ease of printing . Unlike many materials, PETG shrinks minimally, generally 0.3-0.8%. PETG’s chemical composition gives it a meager shrinkage rate compared to other common filaments.
That could account for the difference in dimensions you are experiencing.
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You can increase the size of the model in your CAD program.
Or
In Studio, you can use Scale to increase the size of the model to account for shrinkage. 100.33% should work.
If you are regularly using this filament to produce precise prints, I would use OrcaSlicer, which can include a shrinkage factor in the filament profile. Then you can use accurate measurements in CAD without further adjustment in the slicer.
Trust but verify.
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Just to add to this. If the part is 300mm it means that it has to be diagonal on the bed. To scale it correctly make sure to rotate it so it lines up in x/y, scale and then rotate it back.
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I thought so too, and had initally written instructions to first align the model with x or y before scaling. I don’t scale often, so I checked, using a 300x25x10 step file from Fusion, which aligned with the x axis on import.
Then I Auto-Arranged it with Autorotate, which predictably rotated it 45°. Then I selected the Scale tool:
Notice that the model axes rotated with the model. Scaling X (only) by 100.33% gives this result
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For some reason I remembered having issues with scaling parts that were rotated. Perhaps it was with a much older version? Anyways, thank you for clearing that up.
Have the added Measure feature is so nice.
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When shrinkage is handled in Orca, it only expands the x and y axis, not the z. I don’t think there is significant shrinkage in the z axis. So make sure if you use the scale function in Bambu that you only scale x and y.
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Hello everyone,
I would like to thank you for all the answers first.
Ikarus:
I design parts and molds for model gliders and create the data in CAD. Since several parts have to fit together, I cannot adjust them individually in CAD. I mill the large parts in Plexiglas on a portal milling machine. I would now like to replace the smaller parts by printing them. Your suggestion to use the Orca Slicer and change the shrinkage factor has produced the best results so far.
SimEyeSee:
When I use the scaling function, x and y and z are set automatically. So I can’t just adjust x and y.
Best wishes, Dieter
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There is a check box you can check off to make each axis scale individually.
I am new to Bambu so don’t jump too hard on me for saying this, but filament shrinkage seems to be one parameter but scaling of an entire object is another. I admittedly am used to working on my Prusa i3 MK3S+ and using their software (PrusaSlicer), which has a scale factor that scales on the object level. That is you can say scale the entire object to 150% (all axes) or you can alternatively say scale X 150%, Y 110% and Z 100% (unchanged). That is the kind of functionality I would like to see in Bambu Studio if it is not there somewhere that I have yet to find.
Yes you can scale independently in x/y/z.
Uncheck the uniform scale box to scale each axis independently.
THANK YOU!!! Being new to Bambu Studio, I hadn’t found that yet, so many thanks for helping along a newbie! Much appreciated!
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Hello,
SimEyeSee:
Thank you for the tip. I had overlooked the checkbox.
Regards, Dieter
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Since the days of ultimaker, printing the outer wall first result in more accurate models. Try it with the calibration cube.
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I always factor-in shrinkage when printing large parts that need to be dimensionally accurate. I normally print in ABS and I use a 0.5% shrinkage factor for dimensions greater than 100mm. I don’t bother to factor shrinkage for dimensions less than 100mm. I find that ASA shrinks a little less and so I deduct like 0.35% when using ASA.
These factors work for me when I let the parts cool naturally with the top and door remaining closed. That takes at least an hour for cooling, but I find the parts stay firmly attached to the build plate (the plate shrinks as the part does) and so that approach all but eliminates warping. And it reduces shrinkage and micro-fractures, resulting in a stronger, more durable part.