Bubbly Filament Works Better Than You Think

February 17, 2020 by Danie Conradie 22 Comments

Normally bubbles appearing in your extruded filament would be considered a bad sign, but it turns out you can now buy filament that has been specifically formulated to foam. [Stefan] from CNC Kitchen has doing some experiments with these bubbly filaments, and the results have been very interesting.

The filaments in question are VARIOSHORE TPU and LW-PLA, both by ColorFabb. Both filaments have a blowing agent added to the formulation, which releases gas as the temperature is increased. This causes bubbles to form, creating a cellular structure, which decreases the density and increases the flexibility of the printed part. This isn’t the first time that foaming is sold as a feature, but previously it was only done for aesthetic purposes in Polymaker’s Polywood filament.

Before putting the materials through his excellent test procedures, [Stefan] first goes through the process of tuning the print settings. This can be tricky because of the foaming, which increases the effective volume of the plastic, requiring careful adjustment of the extrusion rate. Foaming in the PLA filament reached its maximum foaming at 250 C, at which its density was 44% of the unfoamed filament.

In testing the physical properties, [Stefan] found that the tensile strength and stiffness of printed parts are reduced as foaming increases, but the impact strength is improved. He concludes that the lightweight PLA can have some interesting applications because of the reduced weight and increased impact strength, with 3D printed RC aircraft being an excellent example of this. It should also be possible to change the between layers, effectively sandwiching the foamed layers between solid skins.

[Stefan]’s videos are an excellent resource for those looking to master the finer points of 3D printing with different materials. He has reinforced prints with carbon fiber, played with extrusion widths and developed an ingenious gradient infill technique.

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3D Printing Skin Or Maybe A Dermal Regenerator

February 15, 2020 by Al Williams 11 Comments

In space — at least on Star Trek — no one can hear you apply a band-aid. That’s too low tech. When a Star Fleet officer gets an ouchie, the real or holographic doctor waves a dermal regenerator over the afflicted area, and new skin magically appears. Science fiction, huh? Maybe not. A group of scientists from Canada recently published a paper on a handheld instrument for depositing “skin precursor sheets” over full-thickness burns. The paper is behind a paywall and if you don’t know how to get it or don’t want to get it, you can see a video from the University of Toronto, below.

Although they use the term 3D printing, the device is more like a paint roller. Several substances merge together in the print head and lay down on the burn in broad stripes.

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A Little Rewiring Teaches A Creality Ender 3 New Tricks

February 14, 2020 by Tom Nardi 36 Comments

The Creality Ender 3 is part of the new wave of budget 3D printers, available for less than $250 from many online retailers. For the money, it’s hard to complain about the machine, and it’s more than suitable for anyone looking to get make their first steps into the world of FDM printing. But there’s certainly room for improvement, and as [Simon] shows in a recent blog post, a little effort can go a long way towards pushing this entry-level printer to the next level.

The first step was to replace the printer’s stepper drivers with something a bit more modern. Normally the Ender 3 uses common A4988 drivers, but [Simon] wanted to replace them with newer Trinamic drivers that offer quieter operation. Luckily, Trinamic makes a drop-in replacement for the A4988 that makes installation relatively easy. You’ll need to change out a few caps and remove some resistors from the board to make everyone play nice, but that shouldn’t pose a challenge to anyone who knows their way around a soldering iron.

Beyond quieter running steppers, the Trinamic TMC2208 drivers also offer direct UART control mode. Of course the Ender’s board was never designed for this, so the MCU doesn’t have enough free pins to establish serial communications with the three drivers (for the X, Y, and Z axes). But [Simon] realized if he sacrificed the SD card slot on the board, the six pins that would free on the controller could be cut and rewired to the driver’s UART pins.

Combined with the Klipper firmware, these relatively minor modifications allows him to experiment with printing at speeds far greater than what was possible before. Considering the kind of headaches that a ~$200 printer would have given you only a few years ago, it’s impressive what these new machines are capable of; even if it takes a few tweaks.

$200 Resin Printer Reviewed

February 14, 2020 by Al Williams 29 Comments

[3DPrintFarm] got an early version of the Phrozen Sonic Mini resin printer. If you look at the video below, he was very impressed with its build quality and results. The price is reported to be $200, although we have seen it on some web sites for a bit more. The build quality does look good, although you have to admit, the motion mechanism on a resin printer is pretty simple, since you just need to move up and down.

The printer uses a monochrome LCD which allows it to cure layers very fast (apparently, monochrome panels pass more ultraviolet light through). The panel also has a higher-rated lifetime than color LCDs

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Cheap Strain Relief By Casting Hot Glue In A 3D Print

February 11, 2020 by Donald Papp 52 Comments

[Daniel Roibert] found a way to add cheap strain relief to JST-XH connectors, better known to hobby aircraft folks as the charging and balance connectors on lithium-polymer battery packs. His solution is to cast them in hot glue, with the help of 3D printed molds. His project provides molds fitted for connectors with anywhere from two to eight conductors, so just pick the appropriate one and get printing. [Daniel] says to print the mold pieces in PETG, so that they can hold up to the temperature of melted glue.

The 3D models aren’t particularly intuitive to look at, but an instructional video makes everything clear. First coat the inside surfaces of the mold with a release agent (something like silicone oil should do the trick) and then a small amount of hot glue goes in the bottom. Next the connector is laid down on top of the glue, more glue is applied, and the top of the mold is pressed in. The small hole in the top isn’t for filling with glue, it’s to let excess escape as the mold is closed. After things cool completely, just pop apart the mold (little cutouts for a screwdriver tip make this easy) and trim any excess. That’s all there is to it.

One last thing: among the downloads you may notice one additional model. That one is provided in split parts, so that one can make a mold of an arbitrary width just by stretching the middle parts as needed, then merging them together. After all, sometimes the STL file is just not quite right and if sharing CAD files is not an option for whatever reason, providing STLs that can be more easily tweaked is a welcome courtesy. You can watch a short video showing how the whole thing works, below.

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Welcome To McDonald’s; Would You Like 3D Printing Resin With That?

February 10, 2020 by Al Williams 33 Comments

University of Toronto researchers have succeeded in converting used cooking oil — from McDonald’s, no less — into high-resolution 3D printing resin. Your first response might be: “Why?”, but thinking about it there are several advantages. For one thing, waste oil is a real problem for the food industry, and thus it can be acquired rather cheaply. An even bigger benefit is that the plastic that originates from this oil is biodegradable. Their 3d-printed butterfly, of course, is made from the recycled resin.

We aren’t chemists, but apparently 3D resin has a lot in common with cooking oil already. The team used a one-step chemical process to convert one liter of McDonald’s greasiest into a little more than 400 milliliters of resin.

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Bringing A Swap Meet 3D Printer Back From The Dead

February 10, 2020 by Tom Nardi 9 Comments

At a recent swap meet, [digitalrice] found what appeared to be a like-new QIDI X-Plus 3D printer. It wasn’t clear what was wrong with it, but considering it retails for $900 USD, he figured the asking price of $150 was worth the gamble. As you might expect, the printer ended up being broken. But armed with experience and a supply of spare parts, he was able to get this orphaned machine back up and running.

The first and most obvious problem was that the printer’s Z axis didn’t work properly. When the printer tried to home the axis, one of the motors made a terrible noise and the coupler appeared to be spinning backwards. From his experience with other printers, [digitalrice] knew that the coupler can slip on the shaft, but that didn’t appear to be the case here. Removing the stepper motor and testing it in isolation from the rest of the machine, he was able to determine it needed replacing.

Unfortunately, the spare steppers he had weren’t actually the right size. Rather than waiting around for the proper one to come in the mail, he took an angle grinder to the stepper’s shaft and cut off the 5 mm needed to make it fit, followed by a few passes with a file to smooth out any burrs. We’re not sure we’d recommend this method of adjustment under normal circumstances, but we can’t argue with the results.

The replaced Z motor got the printer moving, but [digitalrice] wasn’t out of the woods yet. At this point, he noticed that the hotend was hopelessly clogged. Again relying on his previous experience, he was able to disassemble the extruder assembly and free the blob of misshapen PLA, leading to test prints which looked very good.

But success was short lived. After swapping to a different filament, he found it had clogged again. While clearing this second jam, he realized that the printer’s hotend seemed to have a design flaw. The PTFE tube, which is used to guide the filament down into the hotend, didn’t extend far enough out. Right where the tube ended, the filament was getting soft and jamming up the works. With a spare piece of PTFE tube and some manual reshaping, he was able to fashion a new lining which would prevent the filament from softening in this key area; resulting in a more reliable hotend than the printer had originally.

It’s great to see this printer repaired to working condition, especially since it looks like [digitalrice] was able to fix a core design flaw. But a broken 3D printer can also serve as the base for a number of other interesting projects, should you find yourself in a similar situation. For example, replacing the extruder assembly with a digital microscope can yield some very impressive results.