Question Wall delamination under stress?

[Andy]

While working on the cutting board holder, I'm bending my test pieces until they break, and am usually finding that they delaminate along the side walls. I don't think this is a printer calibration problem, since I don't have this problem on prints that aren't being pushed to breaking, but is there anything I can do to prevent this, aside from printing in another orientation (which I'm not super wanting to do)?

Some examples:

 

[Eric]

There are a few things that I would think could help this:

1. Increasing temperature which usually helps with vertical layer adhesion and I would imagine it would help with horizontal adhesion as well. A temperature tower test will demonstrate how quality of appearance declines with temperature increasing, but strength testing it will show hotter = more better. Finding the hottest you can go without quality loss is the key in my experience, sometimes that is hotter than I would choose based on the visual appearance of the temperature tower test but that extra heat is needed for final strength of the part.
   
   
2. Increasing the perimeter line extrusion width for the internal perimeters slightly. There is not a lot of room to wiggle on this one, as too much will cause overflowing molten filament that makes messy layers but it can be very slightly increased as it may be actually slightly too low currently. With PrusaSlicer this can be either a direct measurement or a relative precentage of the nozzle size. For instance a 0.4mm nozzle might use a 0.45mm line width for interior perimeters or 112%. If you go this route I would try increasing that to 113-114% and see if that helps. With Prusaslicer each type of perimeter could have a different width, so you may need this done on the external perimeters or the internal depending on where it delaminates.
   
   
3. Enclosed and ideally heated build chamber. This option sucks but if the plastic laid down previously is hotter, the next line will adhere better than if it is colder.

I would approach them in that order just based on simplicity of the solution. You might be able to reprint the same Gcode file and just manually increase temp on the printer once it's started to do the first test, this helps make sure there is no other variables being changed which makes it confusing.

 

[Andy]

Since this is one continuous line (i.e., the printhead never leaves the print surface), I would think that I could crank the heat without stringing, right? That said, I'm already printing at 200c, so I don't have a lot more room to go before I start to burn the PLA. I'll poke at this though.

I haven't played with different extrusion amounts at certain points (only over/under extruding for the whole print). I'll have to check that out too.

I've considered a build chamber, but it's pretty far down my todo list. Why does that option suck? Just the amount of work involved compared to the first two options?

 

[Eric]

Yeah the build chamber sucks as solution because it's expensive and big, it's very nice to have once it's there though! An actively heated build chamber is necessary for some high performance plastics but could be used a lower setting with PLA to get a more homeogenous part. Heated build chambers mean water-cooled or displaced electronics and motors though so that is a step above just a regular enclosure.