Kinematic Mount For 3D Printer Bed Shows Practical Design

February 9, 2019 by Donald Papp 8 Comments

Aluminum bed with new kinematic mount and base on printer *Son of Megamax*, at the Milwaukee Makerspace

[Mark Rehorst] has been busy designing and building 3D printers, and Son of Megamax — one of his earlier builds — needed a bed heater replacement. He took the opportunity to add a Kelvin-type kinematic mount as well. The kinematic mount and base efficiently constrain the bed in a controlled way while allowing for thermal expansion, providing a stable platform that also allows for removal and repeatable re-positioning.

After a short discussion regarding the heater replacement, [Mark] explains the design and manufacture of his kinematic mount. Of particular note are the practical considerations of the design; [Mark] aimed to use square aluminum tubing as much as possible, with machining requirements that were easily done with the equipment he had available. Time is a resource after all, and design decisions that help one get something working quickly have a value all their own.

If you’re still a bit foggy on kinematic mounts and how they work, you’re not alone. Check out our coverage of this 3D-printed kinematic camera mount which should make the concept a bit clearer.

Purge Buckets To Help With Multimaterial Printing

February 7, 2019 by Lewin Day 7 Comments

3D printing is cool, but most basic fused deposition printers just print in a single color. This means that if you want a prettier, more vibrant print, you need to paint or perform some other kind of finishing process. Multimaterial printers that can switch filaments on the fly exist, but they often have an issue with waste. [3DMN] decided to attempt building a purge bucket as a solution.

[3DMN] was previously familiar with using a purge block when running multimaterial prints. A basic block model is printed along side the actual desired part. The block is printed so that it is at the same layer height as the desired part, so the nozzle can purge cleanly without stringing plastic all over the print bed.

Tired of the waste, [3DMN] designed a purge bucket which moves with the Z-axis of his Geeetech A20M printer. The bucket attaches to the Z-axis with lock nuts and is always at the same height relative to the nozzle, regardless of the stage of printing. When a material change is required, the nozzle moves to the bucket, purges the filament, and then moves back to the print. The bucket features a 3mm silicone wiper to help ensure there is no material left clinging to the nozzle after the purge is complete, and aluminium tape which helps prevent the purged filament sticking to the walls of the bucket.

[3DMN] notes there’s also a speed increase for some prints, due to no longer needing to print purge objects along with the main part. The parts are available on Thingiverse for those of you wishing to experiment with your own setup.

Multimaterial printing can have some great visual results, and it’s great to see the community providing solutions to improve the process and reduce the waste involved. We’ve also seen filament splicing, which is another unique approach to multimaterial prints. Video after the break.

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Finite Element Analysis Results In Smart Infill

February 6, 2019 by Brian Benchoff 16 Comments

If you would like to make a 3D print stronger, just add more material. Increase the density of the infill, or add more perimeters. The problem you’ll encounter though is that you don’t need to add more plastic everywhere, only in the weak areas of the part that will be subjected to the most stress. Studying where parts will be the weakest is the domain of finite element analysis, and yes, you can do it in Fusion 360. With the right techniques, you can make a stronger part on your 3D printer, and [Stefan] is here to show you how to do it.

The inspiration for this build comes from [Adrian Bowyer]’s blog, where he talks about adding ‘fibers’ to the interior of 3D printed objects to increase strength. These ‘fibers’ aren’t really fibers at all, but long, thin, cylindrical voids. The theory of this is that the slicer will interpret this as a hole and place perimeters around these voids, effectively increasing the density of the infill in a local area in the print. Combine this with finite element analysis, and you get a part that is stronger where it needs to be, and doesn’t waste plastic.

However, there is an easier way. Fusion 360 and ANSYS Finite Element Simulation are both free-ish tools that allow for some amount of finite element analysis on an imported 3D object. This can be used to find the weakest part of any 3D print, and it can this can be exported as a 3D mesh. Slic3r has a modifier mesh function, and combining this finite element analysis mesh (printed at 100% infill) with the original part (printed at 10% or so infill) results in something that’s strong where it needs to be, doesn’t waste plastic, and is much easier to set up than [Adrian Bowyer]’s ‘fiber’ technique.

After printing a few 3D printed hooks with varying degrees and techniques of infill, [Stefan] found the baseline of 2 perimeters failed in a test hook at about 50kg load. The Smart Infill hook failed at about 100kg. Not bad, and the fancy-pants hook only weighs about 30% more.

You can check out a video of the entire toolchain and testing below. Thanks [Keith] for sending this one in.

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Hackaday Podcast 004: Taking The Blue Pill, Abusing Resistors, And Not Finding Drones

February 1, 2019 by Mike Szczys 17 Comments

Catch up on your Hackaday with this week’s podcast. Mike and Elliot riff on the Bluepill (ST32F103 boards), blackest of black paints, hand-crafted sorting machines, a 3D printer bed leveling system that abuses some 2512 resistors, how cyborgs are going mainstream, and the need for more evidence around airport drone sightings.

Stream or download Episode 4 here, and subscribe to Hackaday on your favorite podcasting platform! You’ll find show notes after the break.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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3D Print That Charging Dock For Your 3DS

January 31, 2019 by Brian Benchoff 15 Comments

The Switch is the new hotness and everyone wants Nintendo’s new portable gaming rig nestled in a dock next to their TV, but what about Nintendo’s other portable gaming system? Yes, the New Nintendo 3DS can get a charging dock, and you can 3D print it with swappable plates that make it look like something straight out of the Nintendo store.

[Hobby Hoarder] created this charging dock for the New Nintendo 3DS as a 3D printing project, with the goal of having everything printable without supports, and able to be constructed without any special tools. Printing a box is easy enough, but the real trick is how to charge the 3DS without any special tools. For this, [Hobby Hoarder] turned to the small charging contacts on the side of the console. All you do is apply power and ground to these contacts, and the 3DS charges.

Normally, adding contacts requires pogo pins or hilariously expensive connectors, but [Hobby Hoarder] has an interesting solution: just add some metal contacts constructed from LED leads or paper clips, and mount it on a spring-loaded slider. A regular ‘ol USB cable is scavenged, the wires stripped, and the red and black lines are attached to the spring-loaded slider.

There is a slight issue with the charging voltage in this setup; the 3DS charges at 4.6 Volts, and USB provides 5 Volts. If you want to keep everything within exacting specs, you could add an LDO linear regulator, but there might be issues with heat dissipation. You could use a buck converter, but at 0.4 Volts, you’re probably better off going with the ‘aaay yolo’ theory of engineering.

[Hobby Hoarder] produced a few great videos detailing this build, and one awesome video detailing how to print multicolored faceplates for this charging dock. It’s an excellent project, and a great example of what can be done with 3D printing and simple tools.

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This 3D Printer Is Soft On Robots

January 30, 2019 by Al Williams No comments

It always seems to us that the best robots mimic things that are alive. For an example look no further than the 3D printed mesh structures from researchers at North Carolina State University. External magnetic fields make the mesh-like “robot” flex and move while floating in water. The mechanism can grab small objects and carry something as delicate as a water droplet.

The key is a viscous toothpaste-like ink made from silicone microbeads, iron carbonyl particles, and liquid silicone. The resulting paste is amenable to 3D printing before being cured in an oven. Of course, the iron is the element that makes the thing sensitive to magnetic fields. You can see several videos of it in action, below.

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Plastics: PETG

January 29, 2019 by Dan Maloney 30 Comments

You’d be hard-pressed to walk down nearly any aisle of a modern food store without coming across something made of plastic. From jars of peanut butter to bottles of soda, along with the trays that hold cookies firmly in place to prevent breakage or let a meal go directly from freezer to microwave, food is often in very close contact with a plastic that is specifically engineered for the job: polyethylene terephthalate, or PET.

For makers of non-food objects, PET and more importantly its derivative, PETG, also happen to have excellent properties that make them the superior choice for 3D-printing filament for some applications. Here’s a look at the chemistry of polyester resins, and how just one slight change can turn a synthetic fiber into a rather useful 3D-printing filament.

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