I was attempting to strengthen a thin-walled model at a hinge joint, and the hinges all cracked along the modifier boundary line, making them far weaker than no modifier at all.
You can see in the photo below how the edges don’t melt together as this boundary edge is clean with almost no scarring.
Surely there’s some way to make the two outer walls along the boundary overlap enough to prevent this plane of weakness?
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Welcome to the community.
Thanks for posting clear photos. It would help if you could upload the 3MF file, unmodified and as you had it set up when you clicked print.
In the meantime, without direct access to the model and how the modifiers were set up, the photos suggest that there is a clean gap which would be consistent with this part of the picture.
I know that’s not what you want, but without seeing how the model was sliced, it’s only a guess that you may have inadvertently created a gap as opposed to just a focused modifier.
Hi Olias,
Thanks for your feedback.
Here are some more pictures to illustrate the slice, as well as the attached 3MF file.
Showing the modifier cube
TestModifierboundary.3mf (223.3 KB)
I have taken a look at the file.
You changed the wall count in the modified section.
To resolve this choice, the modified area gains its own walls and the non-modified areas have their walls ended at the meeting point.
I noticed your infill type is grid and your infill percentage is 6% for the rest of the model. This is very low for something you hope will have a strong hinge attached to it.
Personally I would change the infill type to Gyroid and increase the base infill percentage to at least 20% and the modifier section to 35%. I would leave the walls as they are for the rest of the model.
It will increase the print time marginally (adds around 60 seconds to the part you provided.
This looks like you are building a storage case, possibly a rugged one. 6% infill and especially grid isn’t going to help that. Personally I avoid Grid infill type and anything less than 15% for a structural part needs a really good reason to have so little.
Opinions differ though.
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Hi Malc,
Thanks for the response.
It’s just a mockup to highlight the issue so please disregard the infill settings.
From the image, it looks like the modifier overlaps the non-mofied wall, but can’t see it clearly enough to be sure.Can you go into more detail about how to achieve the following?
To resolve this choice, the modified area gains its own walls and the non-modified areas have their walls ended at the meeting point.
This occurs when you have a different number of walls for the base part and the area within the modifier region.
My latest Fidget Spinner range has different portions of the model set with different number of walls, but, because those portions are separate sections and do not physically touch one another, there is no point at which they meet.
Outer section on this one from the range.
You should increase the infill on areas you prefer to strengthen.
Thanks for uploading the 3MF, it really takes out the guesswork. I’m printing a sample of this now because I want to see for myself. However, I do not expect to get the same results since I am using a different filament(Bambu PLA Matte).
However, here is what I’m seeing that meshes with your photo.
This line is doing exactly what modifier should be doing. But your filament is behaving oddly.
So here is an experiment you can try out to “force” the walls to adhere. Experiment with outer wall thickness. This example is truly extreme and I don’t expect you to use this value(maybe make it 0.55) but I used 0.8 to really make the image “pop out” and show the effect. In this example, you can see just how much thicker the slicer thinks the outer wall(orange) is compared to the interior wall(yellow).
Now one thing you can do is break apart the modifiers so that there are two of them. The shortcut for this is to click on the modifier in the objects window then CTRL-C and then CTRL-V to make a copy under the same assembly. Then move and modify the thickness.
This produces a slice that will eliminate the seam.
Appearance from the back angle. No seams on the back at all.
Ahah! Yes, that does fix the issue! Thanks for the clarification!
It’s odd that BL hasn’t created a fix for this as I’m sure this will be a mistake that others will easily make when dabbling with modifiers. I’ve also seen it working on other slicers, so it can be done.
Hey Olias,
Thanks for looking into this for me.
Some interesting ideas there and surely some food for thought.
The good news is that Malc just gave me the advice to avoid changing the perimeters and instead increase the infill density.
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I know i am a little late to the party but there is a workaround, although it is easier if you have the original CAD models. I made a similar model to OP to illustrate this however, it can be done with jus the stl and some patience.
You can bring in a copy of the original model and scale it down so that it is 1 line width inside of the orginal model, change this to a modifier and be sure it is centered in the part. You can then cut out sections of the modifier that you dont want to interact with the orginal model and make your changes. For this example I just upped the infill.
Forum test.3mf (33.1 KB)