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What Actually Causes Warping In 3D Prints?

October 14, 2024 by 35 Comments

The 3D printing process is cool, but it’s also really annoying at times. Specifically, when you want to get a part printed, and no matter how you orientate things, what adhesion aids you use or what slicer settings you tweak, it just won’t print right. [David Malawey] has been thinking a little about the problem of the edges of wide prints tending to curl upwards, and we believe they may be on to something.

Obviously, we’re talking about the lowest common denominator of 3D printing, FDM, here. Other 3D printing technologies have their gotchas. Anyway, when printing a wide object, edge curling or warping is a known annoyance. Many people will just try it and hope for the best. When a print’s extreme ends start peeling away from the heat bed, causing the print to collide with the head, they often get ripped off the bed and unceremoniously ejected onto the carpet. Our first thought will be, “Oh, bed adhesion again”, followed by checking the usual suspects: bed temperature, cleanliness and surface preparation. Next, we might add a brim or some sacrificial ‘bunny ears’ to keep those pesky edges nailed down. Sometimes this works, but sometimes not. It can be frustrating. [David] explains in the YouTube short how the contraction of each layer of materials is compounded by its length, and these stresses accumulate as the print layers build. A simple demonstration shows how a stack of stressed sections will want to curl at the ends and roll up inwards.

This mechanism would certainly go some way to explain the way these long prints behave and why our mitigation attempts are sometimes in vain. The long and short of it is to fix the issue at the design stage, to minimize those contraction forces, and reduce the likelihood of edge curling.

Does this sound familiar? We thought we remembered this, too, from years ago. Anyway, the demonstration was good and highlighted the issue well.

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Calculating The True Per Part Cost For Injection Molding Vs 3D Printing

October 14, 2024 by 45 Comments

At what point does it make sense to 3D print a part compared to opting for injection molding? The short answer is “it depends.” The medium-sized answer is, “it depends on some back-of-the-envelope calculations specific to your project.” That is what [Slant 3D} proposes in a recent video that you can view below.  The executive summary is that injection molding is great for when you want to churn out lots of the same parts, but you have to amortize the mold(s), cover shipping and storage, and find a way to deal with unsold inventory. In a hypothetical scenario in the video, a simple plastic widget may appear to cost just 10 cents vs 70 cents for the 3D printed part, but with all intermediate steps added in, the injection molded widget is suddenly over twice as expensive.

In the even longer answer to the question, you would have to account for the flexibility of the 3D printing pipeline, as it can be used on-demand and in print farms across the globe, which opens up the possibility of reducing shipping and storage costs to almost nothing. On the other hand, once you have enough demand for an item (e.g., millions of copies), it becomes potentially significantly cheaper than 3D printing again. Ultimately, it really depends on what the customer’s needs are, what kind of volumes they are looking at, the type of product, and a thousand other questions.

For low-volume prototyping and production, 3D printing is generally the winner, but at what point in ramping up production does switching to an injection molded plastic part start making sense? This does obviously not even account for the physical differences between IM and FDM (or SLA) printed parts, which may also have repercussions when switching. Clearly, this is not a question you want to flunk when it concerns a business that you are running. And of course, you should bear in mind that these numbers are put forth by a 3D printing company, so at the scale where molding becomes a reasonabe option, you’ll also want to do your own research.

While people make entire careers out of injection molding, you can do it yourself in small batches. You can even use your 3D printer in the process. If you try injection molding on your own, or with a professional service, be sure to do your homework and learn what you can to avoid making costly mistakes.

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That’ll Go Over Like A Cement Airplane

October 8, 2024 by 37 Comments

Most of us have made paper airplanes at one time or another, but rather than stopping at folded paper, [VirgileC] graduated to 3D printing them out of PLA. Then the obvious question is: can you cast one in cement? The answer is yes, you can, but note that the question was not: can a cement plane fly? The answer to that is no, it can’t.

Of course, you could use this to model things other than non-flying airplanes. The key is using alginate, a natural polymer derived from brown seaweed, to form the mold. The first step was to suspend the PLA model in a flowerpot with the holes blocked. Next, the flowerpot gets filled with alginate.

After a bit, you can remove the PLA from the molding material by cutting it and then reinserting it into the flower pot. However, you don’t want it to dry out completely as it tends to deform. With some vibration, you can fill the entire cavity with cement.

The next day, it was possible to destroy the alginate mold and recover the cement object inside. However, the cement will still be somewhat wet, so you’ll want to let the part dry further.

Usually, we see people print the mold directly using flexible filament. If you don’t like airplanes, maybe that’s a sign.

Mechanical Tool Changing 3D Printing Prototype

October 8, 2024 by 5 Comments

Tool changing 3D printers are hot. The idea is that instead of switching filament, you swap out hot ends or other tools. That isn’t a new idea. However, most tool changers are expensive. [Engineers Grow] has one that is simple and inexpensive, relying on the printer’s own motors and some clever mechanics.

The first step was to make a modified extruder that allowed the filament to load and unload. The first attempt didn’t work well, but that is the nice thing about 3D printing — it is easy to try again. There is only one extruder, which is good from the standpoint that you don’t need a control board with many outputs and you avoid the expense of multiple extruders.

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Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

3D Printering: Listen To Klipper

October 8, 2024 by 10 Comments

I recently wrote about using Klipper to drive my 3D printers, and one natural question is: Why use Klipper instead of Marlin? To some degree that’s like asking why write in one programming language instead of another. However, Klipper does offer some opportunities to extend the environment more easily. Klipper runs on a Linux host, so you can do all of the normal Linux things.

What if you wanted to create a custom G-code that would play a wave file on a speaker? That would let you have custom sounds for starting a print, aborting a print, or even finishing a print.

If you recall, I mentioned that the Klipper system is really two parts. Well, actually more than two parts, but two important parts at the core. Klipper is, technically, just the small software stub that runs on your 3D printer. It does almost nothing. The real work is in Klippy, which is mostly Python software that runs on a host computer like a Raspberry Pi or, in my case, an old laptop.

Because it is Python and quite modular, it is very simple to write your own extensions without having to major surgery or even fork Klipper. At least in theory. Most of the time, you wind up just writing G-code macros. That’s fine, but there are some limitations. This time, I’m going to show you how easy it can be using the sound player as an example.

Macros All the Way Down

Normally, you think of gcode as something like: G1 X50 Y50. Some of the newer codes don’t start with G, but they look similar. But with Klipper, G1, M205, and MeltdownExtruder are all legitimate tokens that could be “G-code.”

For example, suppose you wanted to implement a new command called G_PURGE to create a purge line (case doesn’t matter, by the way). That’s easy. You just need to put in your configuration file:

[gcode_macro g_purge]
gcode:
# do your purge code here

The only restriction is that numbers have to occur at the end of the name, if at all. You can create a macro called “Hackaday2024,” but you can’t create one called “Hackaday2024_Test.” At least, the documentation says so. We haven’t tried it.

There’s more to macros. You can add descriptions, for example. You can also override an existing macro and even call it from within your new macro. Suppose you want to do something special before and after a G28 homing command:

[gcode_macro g28]
description: Macro to do homing (no arguments)
rename_existing: g28_original
gcode:
M117 Homing...
g28_original
M117 Home done....

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First Benchies In Stainless Steel, With Lasers

October 7, 2024 by 19 Comments

DIY 3D printing in metal is a lot more complicated than we thought. And this video from [Metal Matters] shows two approaches, many many false starts, and finally, a glorious 78.9% success! (And it’s embedded below for your enjoyment.)

The first half of the video is dedicated to the work on a laser welding system that doesn’t pan out in the end at all. But the missteps are worth watching as well, and they hammer home the difficulties of melting metal reliably with nothing more than coherent light. Things like reflection, the difficulty of getting good process control cameras, and finally the whole thing slumping as multiple layers stack up on each other make this approach to 3D construction look nearly impossible.

Indeed, around halfway through the video, the focus shifts toward a metal-powder sintering machine, and this one is a success! Metal dust is deposited layer by layer, and fused with a totally different laser. The tricky bits here range from esoteric problems like making the laser fuse the metal dust without blasting it, to simple things like the geometry of the scraper that ensures even layer heights. And once you’ve got all that down, getting a good pattern down for 2D infill in metal is non-trivial.

A sweet half-scale metal Benchy emerges at the end, so why does [Metal Matters] call this a 78.9% success? Because that’s the density of the final print, and he is shooting for 100%. But we wouldn’t be so harsh. We’ve seen how far he’s come since the first machines, and this is a huge advance. We’re looking forward to the next video update in a year or two!

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Tinkering With Klipper: Making The ManiPilator Robotic Arm

October 6, 2024 by 15 Comments

[Leo Goldstien]’s entry into the world of robotics has been full of stops and starts. Like many beginners, he found traditional robotics instructions overwhelming and hard to follow, bogged down with dense math that often obscured the bigger picture. So he decided to approach things differently and create something with his own hands. The result? A 3D-printed robotic arm he affectionately calls “ManiPilator.”

This article is the first in a three-part series documenting [Leo]’s hands-on approach to learning robotics from the ground up. Building ManiPilator became an opportunity to learn by doing, and the project took him on a journey of experimenting, failing, and eventually succeeding in tasks that seemed deceptively simple at first glance. Each hurdle provided him with insights that more traditional learning methods hadn’t delivered. Below is one of the videos [Leo] captured, to show one step in the process: doing a check using multiple motors.

To make his project work, [Leo] relied on open-source software like Klipper, piecing together code and hardware in a way that made sense to him. In sharing his story, he offers fellow beginners an approachable perspective on robotics, with practical insights and candid reflections on the challenges and breakthroughs.

[Leo]’s project shows that there’s more than one way to start exploring robotics, and that sometimes the best way to learn is simply to dive in and start building. Follow along with his journey as he tackles the complexities of robotics, one step at a time.

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