How to strengthen this part or stop it from breaking?

[supple patrol]

I'm working on making a lid for a box, a sliding lid. I don't want the walls to be too thick, but the part keeps breaking at the layer lines upon inserting the lid the first few times. Any tips on how to better this design? <@&1122587817768398938>

am I not giving it enough clearance? I want it to be a friction fit so the lid won't slide off upon light shaking

I'm testing a version now with a full chamfer edge on both the top and bottom of the lid, so the edge of the lid is pointy

it happens only with silk PLA which I understand is weaker and has worse layer adhesion than regular PLA

I'm printing it slower and hotter as well

The place this separated was here:

[ember mauve]

You may be at the limits of silk PLA. But as far as design, you could switch to a dovetail shape versus a V.

Something like the bottom.

And then fillet both corners as much as possible.

[ember mauve]

Maybe change the angle, instead of it being 45 or 60 degrees make it like 80 so it’s almost vertical but still tapered, that’ll be the corresponding box wall thicker.

[tidal epoch]

Printing the box at an angle would also help a lot, but would require some support so it doesn't fall over. Just so the layer lines aren't in line with the cutout. You're basically concentrating force at the weakest part of the print with that sort of lid.

[supple patrol]

yeah, the idea was that the lid could be used both ways to prevent users from breaking it by placing the lid the wrong way

I wanted to test something like this too, but maybe it's not any better?

I cut off a piece of the "rail" part so there is a thicker part around the stress point

@ember mauve thank you so much for the sketches, those are very helpful!

[supple patrol]

I have thought about this, it just seems very inconvenient for this design, but it's definately worth a shot!

[tidal epoch]

As long as your printer can do a standard 45 degree overhang it really doesn't need that much support, just enough that it will stay stuck to the bed and not fall over. I know there are some youtube videos that cover it if you do a bit of searching.

[supple patrol]

The biggest problem I see with this is that the item in making may lose its functionally, if there is too much friction on the top surface inside the tray

They are used for diamond painting, and aligning the little squares neatly next to each other

So where the drills/diamonds are sliding around needs to be smooth

@tidal epoch here, how it's used

[tidal epoch]

Yeah, having layer lines inside the tray might get in the way there

[supple patrol]

I'll test the dovetail and see if that's stronger and less prone to breaking. It will at least make it less possible for users to break it due to inserting the tray the wrong way

[supple patrol]

and I'll try my cutout method first, since I like lid to be able to go in both ways

thank you all for the ideas, I love this community! ❤️

[ember mauve]

You could also add a 1 layer visual indicator for the top of the lid if you’re worried about them inserting it the wrong way.

[sand storm]

One good way to make thin strong walls is to use a .8 nozzle. One .8 wall is stronger than 2 X .4. In advanced setting tighten the nozzle settings very tight so there is little extra. Some defaults are as high as .46 and 20% on first layer. Especially infill cut to .41 and final layer .4 assuming it’s a .4 you’re using.