this is my first post and I need a little help from the experts here. I designed a sorting insert for a board game. The insert measures 260 x 78 x 40 mm. The insert has a 27 mm thick bottom with 5% rectilinear infill. Above the base there are four compartments for cards and small parts, which consist of walls with a thickness of 2 mm on the inside and 3 mm on the outside.
During printing, a protruding edge of around 0.5 mm was created at the transition from the base to the open area of the compartments above. The edge continues up to the top. In addition, all four corners of the insert have bent slightly upwards.
What could be the reason for this? I am grateful for any advice!
It is not uncommon for long parts to detach from the plate due to insufficient adhesion.
To solve, wash the plate with warm water and mild dishwashing detergent (don’t scour the surface), and dry with paper towel or a clean towel. Avoid putting fingers on the surface. Adhesion will be better, but applying liquid glue may improve adhesion and release significantly.
My guess is that’s due to the print detaching and warping upwards, perhaps even resulting in minor collisions of the nozzle, and then a few layers will be ruined.
The fact that it perfectly matches the transition height suggests that it’s related to the printing speed which sometimes changes based on the area of a layer for parts like this. Look at the filament speed in the preview section to see if this is the case. You can override the outer wall speed with a lower setting in the speed tab.
I haven’t used brim yet, but will give it a try. And I cannot see any change in speed or flow in the preview under / on / above the area of the protruding edge.
What surprises me most about the edge is that it extends all the way to the top. When I measure the insert, it is exactly the same size above the edge as I defined with Fusion (78 mm). Below the edge, the insert is between 0.2 and 0.6 mm narrower than in the design.
Could this be due to different contraction behavior of the two areas? Does the lower, closed area with the infill contract more during cooling than the upper, open area with the thin walls?
That is a big part of the issue plus your layer time makes a drastic change from the large surface area to just the rising walls. Another factor is that this transition is far away from the build plate therefore you do not get the benefit of the heat and X-Y dimensional retention force of the build plate.
You likely can get some improvements by changing the infill type , reduced infill to Wall overlap, Print sequence with outer wall last, higher wall perimeter count for example, or as a designer of the part make a feature in that area that will hide this.
It sounds like the part is shrinking at the corners and lifting off the bed mid print. After this happens every subsequent layer is likely more compressed by the lifting plus it’s misaligned from the prelifted layers because of the curling.
I added brim, changed the print sequence, the wall perimeter and reduced the speed etc. The result was two prints that looked more or less the same.
I don’t feel I could get to grips with the problem this way. I have now split the inlay into two parts, put four pins on the top of the bottom part and four holes on the bottom of the top part to align them neatly. I will simply glue them together.
