Earlier quoted context omitted.
layer lines. That said, if the part is small, and one can afford to print w/ 100% infill just put it in a tray of salt and bake to re-melt/re-flow to make a (more) solid part. https://x3d.com.au/blogs/tips-and-tricks/pla-baking-the-secr...
Wood strength is high with the direction of the grain and weak across the grain, is that a property of layer lines too? I just couldn't find any source that claim it to be so.
Show HN: 3D printing giant things with a Python jigsaw generator
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Re: Show HN: 3D printing giant things with a Python jigsaw generator
#32Earlier quoted context omitted.
Each continuous strand of filament is kind of like a wood fiber, in the sense that the strand is much stronger than the connection to the other strands. Of course 3d printers lay these strands in a 2d plane (and stack layers of these 2d planes), whereas trees grow in more-or-less one dimension. So wood has one strong direction and two weak ones, while 3d prints have two strong directions and one weak direction. And o…
That much I'm aware of, but as I mentioned in previous comments, with wood strength is high in the direction of the grain but weak across the grain, plenty of academic studies confirm that (and it takes little to verify it empirically). With 3D printing, despite the analogy, I couldn't find any sources for strength along/across the "grain" so i'm not sure how accurate that analogy really is.
With 3d prints this is usually framed as layer adhesion. Within one layer (so in the x-y plane) you are basically "along the grain" since the strands form loops and other 2d shapes within the layer. Between layers (== in z direction) you only have the adhesion between different strands holding the layers together, which is equivalent to going across the grain in wood.
CNC kitchen on youtube does a lot of strength and impact testing, e.g. [1] (results at 9:55). "Across the grain" you have half the strength in PLA (and similar numbers in all filament types except TPU). Or if you prefer manufacturer numbers, [2] is the datasheet for a random PLA filament. It also shows worse numbers in every metric in the Z direction (across the grain).
The difference isn't as severe as in wood, but it's big enough that it is something you have to consider in structural parts
[1] https://youtu.be/dOzVuoBP9gY?t=535
[2] https://polymaker.com/wp-content/uploads/lana-downloads/Poly...
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#33I been thinking an openscad->cura pipeline would be cool. This post is very similar and inspiring. Imagine running a custom action or pipeline and getting a physical object pop out in the shed. Pretty awesome. I also like the idea as git as the way to share and remix 3d printing instead of (as well as) the various STL sites.
You can link openscad to a slicer, at least in the dev snapshots, press F8 and your model opens in your slicer of choice.
Makerworlds customizer is simply a web version of OpenScad. Upload your OpenSCAD script and good to go
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#34This is great I'm going to have to try this out. I've got my own openscad dovetail joint scripts, but this seems more refined.
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#35Skipping teeth? Why not scale the whole series of dove tails for detected cases?
That requires re-working the design for the fit tolerance.
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#36> "The strength comes from the tightening/wedging effect when pulling the join apart. If the dovetail is tapered, the join can also tighten when it aligns too – this is highly desirable for gluing, as it means the glue will not be scraped away." While true, dovetail and other traditional woodworking joints borrow their strength from using the wood grain to support the joint. I don't know a lot about 3D printing but I…
https://github.com/TengerTechnologies/Bricklayers
This came at a perfect time, then - you can cause each adjacent layer to be offset by half the layer height, to maximize the strength.
Annealing parts by baking them at the right temperature for a sufficient length of time is relatively easy to do. Printing at higher temperatures and slower speeds to ensure layers are melted together also results in higher strength parts.
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#37While this is nice for things like the speaker enclosure I cant help but recoil in horror from the 3d printed arcade cabinet - so much plastic. I get how this enables shapes and other niceties but between aesthetic and the environment I'll take boring and recyclable any day.
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#38Re: Show HN: 3D printing giant things with a Python jigsaw generator
#39I'm really happy to see OpenSCAD stuff here in HN. Of course it has some downsides (not being able to measure an object is the main one...), but it is an underrated tool. I'm using it as my main 3D modeling tool for three years, and I even gave I course about it last year. No regrets, and I never felt that I needed to learn Fusion or similar
For me, the big problem with OpenSCAD and the reason I let go of it quickly is the lack of constraint-based modeling. For example, if I want to design a cup and I want my handle to have a 30mm round hole that is tangent to the walls of the cup, I want to be able to adjust the thickness of the handle and the size and shape of the cup while keeping these properties. And I don't what do do the maths myself if I can avoi…
Other big problem is one demonstrated also by the article; openscad is not great at any rounded shapes because it is mostly polygon based. So even if you write out the maths explicitly they might end up being wrong because of the difference between true round and the polygonal approximation
Re: Show HN: 3D printing giant things with a Python jigsaw generator
#40I'm really happy to see OpenSCAD stuff here in HN. Of course it has some downsides (not being able to measure an object is the main one...), but it is an underrated tool. I'm using it as my main 3D modeling tool for three years, and I even gave I course about it last year. No regrets, and I never felt that I needed to learn Fusion or similar
OpenSCAD recently got a Measure tool: https://www.youtube.com/watch?v=Q_AEHI2o-6Q OpenSCAD's strength --- that it makes it easy to create 3D designs which are easily represented mathematically using cubes, spheres, cylinders, cones, and assemblies and distortions thereof is also its weakness --- what one can do in OpenSCAD is strongly bounded by one's fluency in mathematics/geometry/trigonometry (says the guy who is…
Being able to do object oriented programming is going to make reasoning about geometrical objects much easier.
I like the measuring tool but I prefer doing something more permanent like labeling it.