Giant 3D Prints Piece-by-Piece

January 16, 2022 by Al Williams 18 Comments

While FDM printers have gotten bigger lately, there’s almost always going to be a part that is bigger than your bed. The answer? Break your design into parts and assemble them after printing. However, the exact method to do this is a bit of a personal choice. A mechanical engineering student wrote:

After researching the state of the art as well as your ideas here on reddit, I realized, that there are almost no universal approaches to divide a large part and join the pieces which maintain mechanical strength, precisely position each segment, and also counteract tolerances due to the FDM-process.

Therefore I tried to develop a universal method to segment large trim parts, additively manufacture each segment and finally join those segments to form the desired overall part.

The result is a research paper you can download for free. The method focuses on thin parts intended as automotive trim, but could probably be applied to other cases.

You can read about the thought process, but the final result was a joggle — a joint made with a rabbet and tongue. Adhesive holds it together, but the joint offers advantages in constraining the final product and the transmission of force in the assembly. Judging by the picture, the process works well. It would be interesting to see slicer software develop the capability to segment a large model using this or a similar technique.

Of course, you can just build a bigger printer, at least to a point. It seems, though, that that point is pretty big.

Recycling Soda Bottles Into Filament To Print Smaller Soda Bottles

January 15, 2022 by Lewin Day 32 Comments

Thermoplastics are great, because you can melt them down and reform them into whatever you like. This is ably demonstrated by [The Q] by recycling old soda bottles into usable 3D printer filament.

Cute, huh? Why aren’t Coca-Cola making these? Tiny fake grocery items already proved hugely popular in Australia.

Soda bottles are usually made out of PET plastic, or polyethylene terephthalate, which is one of the most popular thermoplastics in modern society. A soda bottle can be cut into a continuous long, thin strip with the use of a simple hand-operated machine that slices the bottle with a blade. This strip of plastic can then be fed through a heated nozzle in order to produce filament for 3D printing. [The Q] demonstrates both parts of this process, including using a motorized reel to take up filament as the bottle material is fed through the extruder.

The filament is then demonstrated by printing tiny versions of soda bottles. [The Q] fills these with soda and gives them the appropriate lids and labels for completion’s sake. It’s a neat way to demonstrate that the filament actually works for 3D printing. It bears noting that such prints are almost certainly not food safe, but it’s really a proof of concept rather than an attempt to make a usable beverage container.

Like similar builds we’ve seen in the past, the filament is of limited length due to the amount of plastic in a single bottle. We’d like to see a method for feeding multiple bottles worth of plastic into the extruder to make a longer length spool, as joining lengths of filament itself can be fraught with issues. Video after the break.

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Improve Your Front Panels

January 15, 2022 by Al Williams 58 Comments

For many of us, the bane of electronic projects is making a professional-looking enclosure. Sure, 3D printing has made it easier to make the actual enclosure, but there’s still the problem of labeling it. [Richard Langner] has the answer with something he calls easy front panels. You can read about it or watch the tutorial video below.

The concept is easy enough. You create your beautiful artwork in your choice of graphics programs. The example uses Inkscape, but you could do it in anything, even PowerPoint. You print it out and cut it to size. You could, of course, print it in color or — as the example does — color it in by hand.

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3D Printering: Getting Started With Universal Bed Leveling

January 14, 2022 by Al Williams 10 Comments

Last time we talked about how Marlin has several bed leveling mechanisms including unified bed leveling or UBL. UBL tries to be all things to all people and has provisions to create dense meshes that model your bed and provides ways for you to adjust and edit those meshes.

We talked about how to get your printer ready for UBL last time, but not how to use it while printing. For that, you’ll need to create at least one mesh and activate it in your startup code. You will also want to correctly set your Z height to make everything work well. Continue reading “3D Printering: Getting Started With Universal Bed Leveling” →

3D Printed Sensor For Finding Wind Direction And Likely Much More

January 11, 2022 by Ryan Flowers 35 Comments

Have you ever wondered how an electronic wind vane translates a direction into a unique signal? It seems as though it might be very complicated, and indeed some of them are. [martinm] over at yoctopuce.com has an excellent writeup about measuring wind direction using just a single, easily printed disk and some phototransistors.

Commercial weather vanes often use complicated multi-tracked disks with magnets and reed switches, conductive traces and brushes, or some other means of getting a fine resolution. Unfortunately some of these are prone to wear or are otherwise more complicated than they need to be.

What makes [martinm]’s solution unique is that they have applied previous research on the subject to a simple and durable 3d printed wind vane that looks like it’ll be able to handle whatever global warming can throw at it. The encoder’s simplicity means that it could likely be used in a large number of applications where low resolution position sensing is more than enough- the definition of a great hack!

Adding more tracks or even more disks would enable higher resolution, but the 12 degree resolution seems quite good for the purpose. Such a neat wind vane design will surely be welcome if you want to 3d print your own weather station. Thanks to [Adrian] for the great tip!

3D Printering: Soldering A Heated Bed

January 11, 2022 by Al Williams 61 Comments

There’s an old saying about something being a “drop in the ocean.” That’s how I felt faced with the prospect of replacing a 12 V heated bed on my printer with a new 24 V one. The old bed had a nice connector assembled from the factory, although I had replaced the cable long ago due to heating issues with that particular printer. The new bed, however, just had bare copper pads.

I’m no soldering novice: I made my first solder joint sometime in the early 1970s. So I felt up to the challenge, but I also knew I wouldn’t be able to use my usual Edsyn iron for a job like this. Since the heated bed is essentially a giant heatsink for these pads, I knew it would require the big guns. I dug out my old — and I mean super old — Weller 140 W soldering gun. Surely, that would do the trick, right?

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Fail Of The Week: 3D Printed Parts That Burn Like NASA’s Rocket Fuel

January 9, 2022 by Dave Rowntree 21 Comments

[Integza] is on a mission to find as many ways as possible to build rockets and other engines using 3D printing and other accessible manufacturing techniques. He had an a great idea – is it possible to 3D print a solid fuelled rocket, (video, embedded below) specifically can you 3D print the rocket grain itself? By using the resin as a fuel and mixing in a potent oxidiser (ammonium perchlorate specifically – thanks for the tip NASA!) he has some, erm, mixed success.

Effective thrust vs grain cross-sectional profile

As many of us (ahem, I mean you) can attest to, when in the throes of amateur solid-propellant rocket engine experimentation (just speaking theoretically, you understand) it’s not an easy task to balance the thrust over time and keep the combustion pressure within bounds of the enclosure’s capability. Once you’ve cracked making and securing a nozzle within the combustion chamber, the easiest task is to get control of the fuel/oxidiser/binder (called the fuel grain) ratio, particle size and cast the mixture into a solid, dry mass inside. The hard part is designing and controlling the shape of the grain, such that as the surface of the grain burns, the actively burning surface area remains pretty constant over time. A simple cylindrical hole would obviously increase in diameter over time, increasing the burning surface area, and causing the burn rate and resulting pressure to constantly increase. This is bad news. Various internal profiles have been tested, but most common these days is a multi-pointed star shape, which when used with inhibitor compounds mixed in the grain, allows the thrust to be accurately controlled.

[Integza] tried a few experiments to determine the most appropriate fuel/binder/oxidiser ratio, then 3D printed a few fuel grain pellets, rammed them into an acrylic tube combustion chamber (obviously) and attached a 3D printed nozzle. You can see for yourself the mach diamonds in the exhaust plume (which is nice) due to the supersonic flow being marginally over-expanded. Ideally the nozzle wouldn’t be made from plastic, but it only needs to survive a couple of seconds, so that’s not really an issue here.

The question of whether 3D printed fuel grains are viable was posed on space stack exchange a few years ago, which was an interesting read.

We’ve seen some more sophisticated 3D printed rocket engines lately, such as this vortex-cooled, liquid-fuel engine, and over on Hackaday,IO, here’s a 3D printed engine attempting to use PLA as the fuel source.

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