Barb Makes Mechanical Pokey Finger With Filament Rivets

We were trolling around Hackaday.io, and we stumbled on [Barb]’s video series called (naturally enough) “Barb Makes Things“. The plot of her videos is simple — Barb points a time-lapse camera at her desk and makes stuff. Neat stuff.

Two particularly neat projects caught our attention: a mechanical pointy-finger thing and the useful 3D-printing-filament rivets that she used to make it. (Both of which are embedded below.) The finger is neat because the scissor-like extension mechanism is straight out of Wile E. Coyote’s lab.

how-to-3d-printing-filament-rivets-reymdd8ufiumkv-shot0004_thumbnail

But the real winners are the rivets that hold it together. [Barb] takes a strand of filament, and using something hot like the side of a hot-glue gun, melts and squashes the end into a mushroom rivet-head. Run the filament through your pieces, mushroom the other end, and you’re set. It’s so obvious after seeing the video that we just had to share. (Indeed, a lot of cheap plastic toys are assembled using this technique.) It’s quick, removable, and seems to make a very low-friction pivot, which is something that printed pins-into-holes tends not to. Great idea!

Continue reading “Barb Makes Mechanical Pokey Finger With Filament Rivets”

3D Internal Structure For Better 3D Printed Objects

Makerbot is in the gutter, 3D Systems and Stratasys stock is only a shadow of their 2014 glory, but this is the best year 3D printing has ever had. Machines are now good and cheap, there’s a variety of various thermoplastic filaments, and printing useful objects – instead of just plastic trinkets – is becoming commonplace.

Gradient-Grid
The standard rectilinear infill from Slic3r

There’s one area of 3D printing that hasn’t seen as much progress, and it’s the software stack. Slicing, the process of turning a 3D object into a Gcode file for a printer has been basically the same for the last few years. Dual extrusion is still a mess, and automated bed leveling is still in its infancy.

One aspect of slicing that has been severely overlooked is infill. Obviously, you don’t want to print plastic trinkets completely solid – only the outside surface matters, and a part with 100% infill is just a waste of plastic. Different slicers have come up with different ways of filling the inside of a print, usually with a grid of squares, triangles, or hexagons.

While the most popular methods of filling in a 3D printed objects do the job of adding a little bit of strength to a print and supporting the top layers of a print, it’s not an ideal solution. The desired strength of the finished part is never taken into account, print artifacts are sometimes visible through the side of a print, and the spacing of the infill grid is completely arbitrary. You can only set a percentage of infill, and telling a slicer to make an internal support grid with 10mm spacing is impossible.

Type A Machines just changed all of this. With the release of their public beta of Cura Type A, the infill for a 3D printed part is also 3D. The dimensions of the infill are predictable, opening the door to stronger and better looking parts.

From the Type A press literature and white paper, this new type of ‘infill’ isn’t; it’s more properly referred to as ‘internal structure’, with proper dimensions between infill features. Instead of a grid of squares or triangles stacked one layer on top of each other, it’s a true structure, with the infill following the perimeter of the 3D printed object.

Generating 3D Infill

3D
Infill generated from Type A Machine’s Cura beta. Note the 3D structure of the infill.

Right now, infill is generated in a slicer by specifying a percentage. Zero percent infill means a hollow object, and 100% infill is a completely solid part. These two edge cases are easy, but anything else means the slicer must fill the part with filament in a grid of tessellating shapes, either rectangles, triangles, or hexagons. With current slicers, the dimensions of this internal structure are, for all practical purposes, random. Printing an object with 20% infill might mean a grid of squares with 5mm or 2mm spacing. Telling the slicer to infill a part with a grid of squares spaced 10mm apart is impossible.

Type A Machine’s latest Cura release changes all of this, allowing a designer to set a precise distance between rows and columns of infill. By defining infill in absolute dimensions, this allows for stronger parts using less infill.

Absolute dimensioning is only one feature of the Type A Machine’s latest release of Cura. Even more exciting is the development of 3D internal structure. Instead of stacking layers of squares, triangles, or hexagons on top of each other, Type A Machine’s Cura uses an infill of cubes turned on their side. While each individual layer of infill looks like a series of triangles and irregular hexagons, when assembled into a printed 3D object, this infill forms a true 3D structure.

The closest comparison to this sort of structure is the difference between graphite and diamond. Both of these materials are made out of the same element, carbon. The physical structure of graphite is just, 1-atom-thick layers of graphene, producing a relatively weak material. Diamond, on the other hand, has a true 3D structure and is one of the hardest materials known to man. While adding 3D structure to the infill of 3D printed objects won’t make the objects any stronger, it will drastically reduce delamination, and be much more resistant to stresses in all three dimensions.

While Type A Machines has done some great work here, it does mean there’s yet another version of Cura to deal with. Type A Machine’s Cura, in addition to the LulzBot edition and the original are now the defacto standard for turning 3D objects into printed parts. Having an open source solution is great, but forking the development this much surely can’t be ideal.

Ask Hackaday: Material Databases

With more and more previously industrial processes coming online in the home shop, people are finding that getting the information that was previously provided by the manufacturer of a hundred thousand dollar machine for their three hundred dollar Shenzen special is not easy.

Some early work from UFID shows how even different Slic3rs can change the expected material properties of a filament.
Some early work from UFID shows how even different Slic3rs can change the expected material properties of a filament.

A common example is this, a hacker purchased themselves a brand new 3D printer off amazon for a price too good to be true. After a week of tinkering with it, a small fire, and a few replacement parts later, they get it to work. After they’ve burned through, perhaps literally, the few hundred grams of filament that came with the printer at the setting recommended by the manufacturer, they do a small blanket order of the different filaments out there. Now comes the trouble, each printer is a little different and each filament has different properties. Most people find that the second spool of filament they feed into their printer doesn’t work at all. What’s the quickest way to get the right temperature, cooling, and feed settings for your printer configuration?

This isn’t a problem for the expensive machines. Epilog, a manufacturer of laser cutters, provides a grid of settings for each material you’re likely to cut, tuned to the different properties of each model of laser cutter they sell. Same goes for the expensive industrial 3D printers, each (very expensive) spool of material has the setting sitting in a chip in the casing. When the spool is slotted in the machine, it reads the settings and adjusts accordingly. All the work of tuning was done in a lab somewhere and the print is, theoretically, guaranteed.

Your Oshpark order would get delayed, your lulzbot support case would be dropped, teensies would ship late, and the Amp Hour would just be the EEVBlog Podcast if this bar burnt down, but it was a great event!
Your Oshpark order would get delayed, your Lulzbot support case would be dropped, Teensies would ship late, and the Amp Hour would just be the EEVBlog Podcast if this bar burnt down, but it was a great event!

While we were at the Bay Area Makerfaire 2016, we had a chance to talk to [Gauthier de Valensart] and buy him a beer at the Hackaday Meet-up. [Gauthier] is from Belgium where he is the founder of a start-up with one of those fancy new TLDs: filaments.directory. The goal of filaments.directory is to create a database of 3D printer materials and link that up with a user’s 3D printer settings. The eventual goal being, much like the industrial printers, a user would be able to simply scan a barcode, or wave the spool over an RFID reader to input the needed settings into his slicing software or printer.

This sounded familiar to me, not the least because I had started work on it as an extension for repables.com when that was a larger focus in my life. In fact, I remember, while I was kicking the idea around to people at MRRF, that they kept telling me someone else was working on a similar project. I wanted to introduce [Gauthier] to the person who was working on the project back then. Since I was at a bar full of people in the industry, I sort of helplessly rotated in my spot trying to find someone who might remember. I spied [whosawhatsis], a common attendee of MRRF, and asked him. Okay, that was easy, [whosawhatsis] informed us that is was his project… introduction complete. Goes to show you what a good networking event buying a bunch of nerds beer can be.

They got a pretty okay logo while they were at it.
They got a pretty okay logo while they were at it.

The project was called, “Universal Filament Identification System,” and it proposed to, “… eliminate the guess-work,” by, “…developing a method for tagging, tracking, and identifying filament for 3d printing in machine-readable formats…” The project appears to be mostly dead now and its domain is a placeholder. I think it suffered from the standard open source feature creep, but the idea is sound.

Which gets us to the questions. There are a lot of difficulties with creating such a system. The first being the data collection. Who should be responsible for measuring the filaments, the materials for laser cutting, or any other process that needs tuned settings? The ideal track, of course, would be for the manufacturers to hold themselves accountable and report on the settings for their filaments. However, many filament manufacturers rely on the ignorance of users to sell dodgy products, it’s only in the interest of a few top-quality ones to do so. If the users do so, then how will the information provided be vetted? You definitely don’t want someone’s ignorance about a faulty thermistor to encourage you to run PLA at 280C.

More and more difficulties arise. How should the information be transferred, etc. What properties should even be recorded? UFID was going as far as to use a color sensor to keep track of colors between batches from 3D printer manufacturers. In the end it’s about creating standards in a standard-less industry by using crowdsourcing. Either way, take a look at what [Gauthier]’s doing (and send him some feedback), read the backlogs of UFID, think about how annoying it was to get the right settings for a laser cutter the last time you used one, and let us know your thoughts in the comments.

This DLP 3D Printer Build Is Going Really Well

We suppose [Dan Beaven] got up one day and said, “I’ll make my own resin 3D printer, with resin management and an advanced separation mechanism!” It’s a build log that shows just how possible it is to roll your own resin printer.

Prints on a dime!
Prints on a dime!

The machine isn’t finished yet, but the example prints coming off it are already very impressive. [Dan] stopped the print midway to get this photo of the detail on the stairs in the standard rook torture test.

[Dan] wants a lot of features from his machine that some of the more polished commercial printers are only now offering. One really nice one is the sliding and twist separation instead of tilt. This will allow for cleaner separation between layers during a print, a lower failure rate, and also faster print times.

He also added resin management with a peristaltic pump. This reduces the size of the build vat, and less resin will be exposed to the elements and wasted. It also means that the printer can run unattended. In the resin handling area of the printer he’s also added a carbon air filter. This lets him run higher performing resins without gassing him out of house and home with fumes.

We like how [Dan] just runs right ahead and puts the printer together. He even points out kludges on the machine that are holding it together long enough for him to print a more functional part for the 3D printer– on the 3D printer. We look forward to the next installment.

Hackaday Prize Entry: A Numerically Controlled RepRap

The story for permanent storage for computers begins with the Jacquard loom. Hackaday commenters that are less clever than a Wikipedia article may argue that it was the earlier Bouchon and de Vaucanson looms, but either way we owe permanent storage methods to loom designers. So the story goes that punched cards for weaving brocades and damask patterns in cloth turned into punched cards for tabulating a census, calculating artillery trajectories, and ends with hundreds of gigabytes of storage in a thumbnail-sized micro SD card.

This story glosses over one important fact. The automated looms of the 17th century were simply a way to make a manufacturing process faster. These automated looms were the forebears of numerically controlled machine tools. These machines, first a lathe, followed by mills and all sorts of metalworking tools, first appearing in the 1950s, used punched tape to store the commands required to mill a part out of metal. Just like the SD card on a modern 3D printer.

For [will.stevens’] Hackaday Prize entry, he’s going back to the roots of automated manufacturing and building a punched card reader for his 3D printer. Is the idea sound? Yes. Is it going to be easy? No, [will] is creating his punched card reader on his 3D printer. It’s the ultimate expression of the RepRap philosophy of self-replication, and an interesting engineering challenge, too.

[will]’s idea for a punch card print controller uses relays. It’s a simple control system that encodes the individual steps for the X and Y axes, along with a length of a line. This printer won’t be able to create lines that go in every direction, instead, there are only 48 possible angles this printer can use out of 360 degrees. At large scales, prints and plots will have the jaggies, but at smaller scales, this control system will be able to print something resembling a circle.

[will] has a PDF of his proposed control system, and he’s already hard at work creating the 3D printed relays and solenoids. [will]’s goal for this year’s Hackaday Prize is to create a 2D plotter – just one axis short of a 3D printer, and he’s well on his way to printing off his own punched cards.

The HackadayPrize2016 is Sponsored by:

3D Printing Compressed Air Tanks

Using PVC pipe as a pressure vessel for compressed air can be a fun and enjoyable hobby. It’s safe, too: while there are are reports of PVC pipe being the cause of accidents, these accidents include a black powder potato gun[1], and welding too close to a PVC pipe containing compressed air[2]. Compressed air stored in a PVC pipe is never a proximal cause in any accident, and the OSHA’s Fatality and Catastrophe Investigation Summaries bear this out; there was no industrial or occupational accident recorded in these summaries where a pressure vessel made out of PVC was the cause of any injury or death[3].

Although PVC pipe can be a perfectly safe, effective, and cheap pressure vessel for hobby applications, it’s not always the best choice. A group of students in Renens, Switzerland are building autonomous robots for the Eurobot competition, and this year’s robot uses pneumatics. That means compressed air, and that means a pressure vessel. Since just about everything else on this robot is 3D printed, they asked the obvious question. Is it possible to 3D print a tank for compressed air?

The tank for this robot would only be used up to about 4 bar (400kPa), and after a few quick calculations, the team discovered the wall thickness – even in a pressure vessel with corners – would be pretty low. The first prototype, a 40mm cube with 20% infill and a hole drilled in the side, held 6.5 bar (650kPa) for an hour. This success didn’t last, though: he second prototype, a 65x40x80mm rectangular prism printed without as much infill, exploded at 5.5bar (550kPa).

The third time’s the charm, and with filleted ribs inside the tank, the third prototype was able to hold pressure up to 6.5 bar. Of course no 3D print is perfect, and the third prototype did leak, but a bit of acrylic spray paint applied to the outer surfaces held the air in.

While it’s not as fun, easy, cheap, rewarding, or safe as using PVC pipe as a pressure vessel, the team did manage to build a 3D printed pressure vessel with a custom shape. You can’t do that very easily with round pipe. And 3D printing opens up all manner of internal structure to experiment with. We’d like to see this developed even further!

Sources: [1], [2], [3]

Motorized Music Box Cranks Out Stairway to Heaven

[Bokononestly] found a lil’ music box that plays Stairway to Heaven and decided those were just the kinds of dulcet tones he’d like to wake up to every morning. To each his own; I once woke up to Blind Melon’s “No Rain” every day for about six months. [Bokononestly] is still in the middle of this alarm clock project right now. One day soon, it will use a *duino to keep track of the music box’s revolutions and limit the alarm sound to one cycle of the melody.

stairway-musicbox-alarm-clock[Bokononestly] decided to drive the crank of the music box with a geared DC motor from an electric screwdriver. After making some nice engineering drawings of the dimensions of both and mocking them up in CAD, he designed and printed a base plate to mount them on. A pair of custom pulleys mounted to the motor shaft and the crank arm transfer motion using the exact right rubber band for the job. You can’t discount the need for a big bag ‘o rubber bands.
In order to count the revolutions, he put a wire in the path of the metal music box crank and used the body of the box as a switch. Check out the build video after the break and watch him prove it with the continuity function of a multimeter. A clever function that should at some point be substituted out for a leaf switch.

We’ve covered a lot of cool clock builds over the years, including one or two that run Linux. And say what you will about Stairway; it’s better than waking up to repeated slaps in the face.

Continue reading “Motorized Music Box Cranks Out Stairway to Heaven”