3d print part crack line start to show up after acetone bath a week later

[Geoff]

Hi,

Crack line start to show up after a week on my 3d printed part with acetone bath treatment, have anyone encounter this before? I spend hour
of making the parts look smooth and shiny with acetone bath but crack line start appearing at the layer joins after a week. I am thinking because
the abs contracts when it dry from the acetone bath. Any idea or fixes?

Thanks

More infill is required, that is all, and more shells.

Acetone is not only smoothing it is eating away at the binding and if there is only 1 shell in your model and not alot of infill, there simply isnt enough to bind the layers together.

Infill isn't just important to stop parts sagging or giving them support during prints, it is also to strengthen the bonds between layers. If you say, have a 25% honeycomb fill that is filled on every layer and use 2 shells, you won't get the split when you acetone your parts.

How you print the object also makes a big difference. Printing tall takes longer, but printing say, an LCD panel standing upright will be much more rigid than one printed long ways and flat, as there is less layers binding it together and longer sections to allow binding to split and crack.