Looking Inside A 3D Printer Nozzle With Computed Tomography

September 28, 2023 by Dan Maloney 16 Comments

Have you ever wondered what’s actually going on inside the hotend of your 3D printer? It doesn’t seem like much of a mystery — the filament gets melty, it gets squeezed out by the pressure of the incoming unmelty filament, and lather, rinse, repeat. Or is there perhaps more to the story?

To find out, a team from the University of Stuttgart led by [Marc Kreutzbruck] took the unusual step of putting the business end of a 3D printer into a CT scanner, to get a detailed look at what’s actually going on in there. The test setup consisted of a Bondtech LGX extruder and an E3D V6 hot end mounted to a static frame. There was no need for X-Y-Z motion control during these experiments, but a load cell was added to measure extrusion force. The filament was a bit specialized — high-impact polystyrene (HIPS) mixed with a little bit of tungsten powder added (1% by volume) for better contrast to X-ray. The test system was small enough to be placed inside a micro CT scanner, which generated both 360-degree computed tomography images and 2D radiographs.

The observations made with this experimental setup were pretty eye-opening. The main take-home message is that higher filament speed translates to less contact area between the nozzle wall and the melt, thanks to an air gap between the solid filament and the metal of the nozzle. They also saw an increased tendency for the incoming filament to buckle at high extruder speeds, which matches up with practical experience. Also, filament speed is more determinative of print quality (as measured by extrusion force) than heater temperature is. Although both obviously play a role, they recommend that if higher print speed is needed, the best thing to optimize is hot end geometry, specifically an extended barrel to allow for sufficient melting time.

Earth-shattering stuff? Probably not, but it’s nice to see someone doing a systematic study on this, rather than relying on seat-of-the-pants observations. And the images are pretty cool too.

Carbon Fiber With 3D Printing

September 25, 2023 by Al Williams 31 Comments

[Thomas Sanladerer] wanted to make 3D prints using carbon fiber and was surprised that it was fairly inexpensive and worked well, although he mentions that the process is a bit intense. You can learn what he found out in the video below.

He used an advanced PLA that can endure more temperature than normal PLA. That’s important because the process uses heat and the carbon fiber resin will produce heat as it cures. The first step was to print a mold and, other than the material, that was pretty straightforward.

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High Temp Resin Means Faster Hot Foil Stamping

September 23, 2023 by Kristina Panos 8 Comments

[This Designed That] does a lot of hot foil stamping. That’s the shiny embellishment you’ll see on wedding invitations and your fancier letterheads. They wanted a way to quickly see if the process is right for a given design, and how it might come together if so. Many of the designs involve letter forms, which they have tried milling out of brass in the past, but the process is fiddly and takes a while. Seeking a faster way to test designs, [This Designed That] turned to 3D printing.

They achieved good results with an Elegoo Mars Pro, but the the most important thing here is the resin needs to withstand at least 130 C, which is the max that [This Deigned That] usually runs it at. The answer was in Phrozen TR300 resin, which can handle temps up to 160 C.

In trials, the stamp heat measured roughly 30 C lower on average than the press, so [This Designed That] kept turning up the heat, but it just wasn’t conductive enough. So they started experimenting with ways to increase heat transfer. First they tried molding metal powder, but it didn’t work. After briefly flirting with electroplating them, [This Designed That] finally tried some aluminum tape, wrapped tight and burnished to the design.

Now the hot foil machine stamps perfectly at only 120 C — the lower end of the standard temperature that [This Designed That] typically runs the thing. They are chuffed at the results, and frankly, so are we. Be sure to check out the process video after the break.

Curious about hot foil stamping machines? Check out this retrofit job.

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Silencing A 3D Printer With Acoustic Foam Isn’t That Easy

September 20, 2023 by Lewin Day 23 Comments

3D printers are supremely useful tools, but their incessant whining and droning can be distracting and tiresome. [Handy Bear] decided to try some simple ways to quieten down their printer using acoustic foam, with mixed results.

The video starts by exploring two different acoustic foams; one black, one white. The latter was found to hold a flame when ignited, making it a poor choice for a 3D printer with many hot components. The black foam, advertised for use in automotive installations, was reluctant to burn at all, and so made a safer choice.

The UP Mini 3 printer is then disassembled to receive its soundproofing treatment. The printer’s various panels all got a healthy lashing of thick sticky insulating foam. This took some work, thanks to the need to cut around various ribs and screw bosses on the panels. Cut appropriately, though, the printed was able to be reassembled neatly with its foam hidden inside.

Unfortunately, the work didn’t have a great effect on the printer’s sound output. That’s perhaps unsurprising, given it still has uninsulated panels like the front window which are still free to radiate sound. The foam did help cut down on fan noise and high-pitch sounds from the printer, but the annoying medium and low pitched noises from the printer’s motors were still very audible.

Using an enclosure or a quieter stepper driver are probably more effective DIY methods to quiet a noisy printer; share your own ideas in the comments. Video after the break.

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Cold Metal Fusion For 3D Printing

September 20, 2023 by Al Williams 13 Comments

When you see the term cold fusion, you probably think about energy generation, but the Cold Metal Fusion Alliance is an industry group all about 3D printing metal using Selective Laser Sintering (SLS) printers. The technology promoted by Headmade Materials typically involves using a mix of metal and plastic powder. The resulting part is tougher than you might expect, allowing you to perform mechanical operations on it before it is oven-sintered to remove the plastic.

The key appears to be the patented powder, where each metal particle has a thin polymer coating. The low temperature of the laser in the SLS machine melts the polymer, binding the metal particles together. After printing, a chemical debinding system prepares the part — which takes twelve hours. Then, you need another twelve hours in the oven to get the actual metal part.

You might wonder why we are interested in this. After all, SLS printers are unusual — but not unheard of — in home labs. But we were looking at the latest offerings from Nexa3D and realized that the lasers in their low-end machines are not far from the lasers we have in our shops today. The QLS230, for example, operates at 30 watts. There’s plenty of people reading this that have cutters in that range or beyond out in the garage or basement.

We aren’t sure what a hobby setup would look like for the debinding and the oven steps, but it can’t be that hard. Maybe it is time to look at homebrew SLS printers again. Of course, the powder isn’t cheap and is probably hard to replace. We saw a 20 kg tub of it for the low price of €5,000. On the other hand, that’s a lot of powder, and it looks like whatever doesn’t go into your part can be reused so the price isn’t as bad as it sounds. We’d love to see someone get some of this and try it with a hacked printer.

We have seen homebrew SLS printers. There’s also OpenSLS that, coincidentally, uses a laser cutter. It wouldn’t be cheap or easy, but being able to turn out metal parts in your garage would be quite the payoff. Be sure to keep us posted on your progress.

Powerful Nerf Blaster Aims To Fire 100 Darts Per Second

September 19, 2023 by Lewin Day 14 Comments

Nerf has made plenty of fully-automatic blasters over the years, but their toys typically lack punch, precision, and fire rate. [3DprintedLife] set about building a blaster to rectify that last shortcoming, aiming for design that could fire 100 darts per second.

The design uses half length darts which tend to fly a little nicer from high-powered blasters. It fires them using belts driven by powerful motors, similar to wheel blasters. The darts themselves are loaded into a drum magazine which has sliders to push the darts into the wheels as the drum rotates by.

It all sounds straightforward enough, but getting it all working in harmony is a challenge—particularly at a fire rate of 100 darts per second. The build video explains the trials and tribulations involved in getting near that fire rate, with darts getting shredded and magazines throwing out parts along the way. A good helping of iterative design helps get everything playing nice, with the darts neatly leaving the magazine and flying downrange at great speed. The slow-motion videos of darts flying out of the blaster in rapid succession are a special treat.

Files are available via Onshape for those looking to dive deeper into the design. We’ve seen some other neat Nerf blasters before, too. Video after the break.

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3D Printing At 100C

September 17, 2023 by Al Williams 23 Comments

Normally, 3D printing with filament takes temperatures of around 200 °C. However, there are some crafting plastics that melt in hot water at 60 °C. You can get spools of similar plastic that prints at very low temperatures, and some 3D printing pens use it. [Lost in Tech] picked up a spool of the stuff meant for medical printing and found that printing with it was a challenge. You can watch a video of the results below.

The first problem is that most printers don’t want to extrude at low temperatures. You can override this or, if you want to print with this plastic — PCL — you can rebuild the printer firmware. He never got bridges to work very well, but some prints came out reasonably well.

Of course, you might wonder why you would care about this kind of plastic. For one thing, it’s apparently safe to work with. If you were printing with students, too, you might be interested in a lower printer temperature. However, it didn’t look like the results were that good. However, it makes you wonder what kinds of filament you could use with a little work that might have some benefit.

The last time we heard about this stuff, someone was printing bones with it. We are always on the lookout for oddball filament to play with.

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