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I printed a case for my phone, a Motorola G4 Plus. I found the model of the casing on Thingiverse

I just downloaded the model, used Meshmixer to check for issues, after that, opened Simplify3d and saved it for printing using an SD Card. The printed size of the model was smaller than expected.

The model designer, says in the description that he used flexible filament. Is it possible than if I change to that filament, the model result is completely different?

Print result - phone casing:

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Of course it can change size... but definitely not in scale you've presented.

Filament as same as many other materials can subject something called shrinkage. It depends on physical properties of the material and as its name suggests cause the dimensions to shrink.

Here is wikipedia article.

The same happens to almost all plastics. But this phenomenon is almost unnoticeable in terms of PLA... well not really...

Bending is mostly caused by shrinkage. We have heated beds (among others) to prevent it. And we use adhesives also to prevent bending so to prevent effects of shrinkage.

It can be also noticed when you print specific volume (and/or specific base surface) and you left the model on the HB until it cools down - the model can come off the HB on it's own even when adhesive was used.

But your "shrinkage" is definitely not that one.

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  • $\begingroup$ Maybe this happeneded, when i was prove that use the meshmixer for check the error's and add better quality $\endgroup$ – Pedro Miguel Pimienta Morales May 6 '19 at 17:03
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    $\begingroup$ @PedroMiguelPimientaMorales you need to edit your model to resize it, then create your gcode again. Some times but some times I got some thingiverse files but I forget to read de instructions which specify print at 90% or print at 120% scale and so on. $\endgroup$ – Fernando Baltazar May 6 '19 at 19:38
  • $\begingroup$ Thanks for your help. $\endgroup$ – Pedro Miguel Pimienta Morales May 7 '19 at 1:40
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No, choosing a different filament type will not result in a different size (unless you use PLA that foams on extrusion, it increases size but then again all other dimensions would not fit either as it expands uniformly). The overall dimensions are defined by the coordinates in the G-code file which is based on the geometry of the model. If the printed model has dimensions that differ in the region of centimeters (like shown in your images) a different filament type will not change the size. Differences in the order of fractions of a millimeter are possible.

Probably the size has accidentally changed while loading the model in one of the tools prior to slicing to G-code.


Sidenote; there are techniques to anneal PLA after printing, you will then observe changes in the size of the part you printed, but I don't think you have annealed the print. From the link above:

On average, you’ll see PLA shrinkage of about 5% and growth of about 2% along the relevant axes. If this shrinkage and growth is going to be a problem, you can compensate for it beforehand during the design and printing processes.

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  • $\begingroup$ I think the same about the problem are in some tools i use for check error from model. I will try again, but just print the first five layers and comparate size. $\endgroup$ – Pedro Miguel Pimienta Morales May 6 '19 at 17:00

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