ABS shrinkage compensation in MatterControl

  • I printed a Lego brick in ABS that ended up to be a little bit smaller than it should be. I read that ABS shrinks after cooling off. Is there a setting in MatterControl that accounts for ABS shrinkage, or do you compensate by scaling the model up a few notches?

  • There's no setting in MatterControl to automatically counteract shrinkage, though you could do it manually by scaling the model in 3D View -> Edit -> Scale.

    ABS typically shrinks by about 3%, so either make the model 3% larger in design software or use the above method to do it in MatterControl.

  • Thanks Ryan,

    that scaling factor would be a cool candidate for a future Material setting in MatterControl.

  • 3% seems like a lot, so I did some calculations. According to this table, the coefficient of thermal expansion of ABS is 73.8x10⁻⁶ m/(m*K). So using dl = L₀ α (t₁ - t₀), the length of an object would shrink by 1.5% when cooling from 235 °C to 25 °C.

    You should also bear in mind that your part will not shrink uniformly. The Z axis will not shrink at all, and different layers cooling at different rates will cause warping.

  • I also noticed that different colors of the ABS PRO filament shrink to a different extend. E.g. in my case the black filament shrunk much more than the white filament. Could it be that the shrinkage is also influenced by the hotend temperature? I used 233 for the black filament and 228 for the white filament.

  • An increased temperature differential would, of course, cause increased thermal contraction. 1.57% @ 233 C as opposed to 1.54% @ 228 C.

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