THP Semifinalist: Theta Printer

thetaThe early 3D printers of the 80s and 90s started off as cartesian bots, and this is what the RepRap project took a cue from for the earliest open source 3D printer designs. A bit later, the delta bot came on the scene, but this was merely a different way to move a toolhead around build plate. We haven’t really seen a true polar coordinate 3D printer, except for [Tyler Anderson]‘s incredible Theta printer.

[Tyler]‘s theta printer is designed to print in as many different materials as possible, without the reduction in build volume that comes with multiple toolheads on more traditional printers. It will be able to lay down different colors of plastic in a huge build volume, and even some of the weirder filaments out there, all in a single print.

The theta printer is based on a polar coordinate system, meaning instead of moving a hot end around in the X and Y axes, the build plate rotates in a circle, and the extruders move along the radius of the circle. This spinning, polar coordinate printer is the best way we’ve seen to put multiple extruders on a printer, and has the added bonus of being a great platform for a 3D scanner as well.

With four extruders, four motors to control the position of each extruder, a rotation motor, and the Z axis (that’s 10 steppers if you’re counting), this is very likely the greatest number of motors ever put in a 3D printer. Most electronics boards don’t support that many stepper drivers, and the one that will won’t be ready for the end of The Hackaday Prize. Right now, [Tyler] is running a fairly standard RAMPS board, running two extruders and R axes in parallel. Still, it’s good enough for a proof of concept.

One interesting aspect of [Tyler]‘s design is something even he might not have realized yet: with a single bed and four extruders, he’s effectively made a 3D printer geared for high-volume production; simply by printing the same part with all the extruders, he’s able to quadruple the output of a 3D printer with the same floor space as a normal one. This may not sound like much, but when you realize Lulzbot has a bot farm producing all their parts, the Theta printer starts to look like a very, very good idea.

Videos of [Tyler]‘s Theta below.


SpaceWrencherThe project featured in this post is a semifinalist in The Hackaday Prize.

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3D Printing a Beautiful Prosthetic Hand for a Stranger

3D Printed Prosthetic Hand

Here’s a story that made us feel all warm and tingly on the inside. [Evan Kuester] is currently studying his Masters in Architecture with a specialty in digital fabrication. His program has access to some nice 3D printers, and he was itching for a good project to use them for. Why not a 3D printed prosthetic hand?

He got the idea after noticing a fellow student on campus who was missing her left hand, and did not have any kind of prosthetic. Eventually he worked up the nerve to introduce himself to her and explain his crazy idea. She thought it was brilliant.

Using Rhino, [Evan] began modeling the prosthetic hand using a plugin called Grashopper. He wanted the hand to be functional as well as aesthetically pleasing, so he spent quite a while working with [Ivania] to make it just right. His first prototype, the Ivania 1.0 wasn’t quite what he imagined, so he redesigned it to what you see above. It’s a beautiful mixture of engineering and art, but unfortunately the fingers don’t move — perhaps an improvement for version 3.0? Regardless of functionality, [Ivania] loves it.

Oh, and [Evan] and [Ivania] are close friends now — in case you were wondering.

[via Make]

Homemade Nerf Blasters With 3D Printed Parts

esltcollagesuperawesome

This spectacular bullpup nerf gun was developed by the guys over at Mostly Harmless Arms. It is complete with 3D printed parts in a variety of colors. The Extension Spring/Latex Tubing (ESLT) Blasters were based off of [Kane]‘s snapoid trigger design with 1/4″ aluminum for the plunger rods which worked out really well. [Prince Edward] adapted [Kane]‘s work and modified it with 3D printing in mind. The original post from 2012 gave an in-depth look into where the idea started.

The documentation for all the printed part files and high quality photos can be found on Nerfhaven. It is really nice to see such a clean design that can be fashioned together on a relatively small budget. This makes these playful nerf blasters easy to duplicate, allowing for a full out office war. Granted, access to a 3D printer is needed, but additive manufacturing devices are getting more and more common these days. Now it’s just a matter of seeing how well they work, which can be deduced from the videos after the break:

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Plan B: An Open Source Powder Based 3D Printer

Open Source Powder Based 3D Printer

3D printers come in all shapes and sizes. Most widely known is the FDM (fused deposition modeling) style, which was the easiest to adapt to a consumer grade machine. We’re still waiting for widespread availability of some of the more advanced 3D printing technologies — so you can guess how excited we were when [Yvo de Haas] dropped us a line on his open-source powder based 3D printer!

Powder based 3D printing is one of the most economic and easy to use technologies in the commercial industry because of one wonderful thing — no support material required! They work by laying down fine layers of powder which can then be bonded together either by laser sintering, or by using a binding agent applied by something similar to an inkjet head. Because of this, the surrounding powder acts as a support for any complex geometry you might need — you can quite literally print anything on this style of machine.

[Yvo] has just finished his own version of this style of 3D printer, called the Plan B. Mechanically similar to a regular 3D printer, his is capable of laying down fine powders, and then binding them together using a hacked HP inkjet cartridge. Check it out after the break.

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Disabled Chiahuahua Gets New Outlook on Life with 3D Printed Cart

Turbo the Two Legged Chihuahua

[Turbo] is a disabled Chiahuahua who has brought in quite a bit of media interest after [Mark Deadrick] designed and 3D printed some new wheels for the pup.

He was born without his front legs due to a genetic defect and quickly became the runt of the litter, as the other pups prevented him from getting much food — at 4 weeks old he only weighed 10 ounces! The couple owning the dogs didn’t want to give up on the little guy but weren’t sure what to do — most veterinarian clinics they visited didn’t offer much support, until they found [Amy Birk] at the Downtown Veterinarian in Indianapolis.

[Amy], the manager of the clinic, had little [Turbo] examined and determined that the there was nothing physically wrong with the puppy, other than his missing legs — this meant [Turbo] could still have a full and happy life — with the help of some extra wheels. The only problem? Dog carts are generally built for their canine users when they stop growing — not much available for puppies — nor would it be cheap.

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Lost PLA Casting With a Little Help From Your Microwave

lost-pla

[Julia and Mason] have been perfecting their microwave-based lost PLA casting technique over at Hackaday.io. As the name implies, lost PLA is similar to lost wax casting techniques. We’ve covered lost PLA before, but it always involved forges. [Julia and Mason] have moved the entire process over to a pair of microwaves.

Building on the work of the FOSScar project, the pair needed a way to burn the PLA out of a mold with a microwave. The trick is to use a susceptor. Susceptors convert the microwave’s RF energy into thermal energy exactly where it is needed. If you’ve ever nuked a hot pocket, the crisping sleeve is lined with susceptor material. After trying several materials, [Julia and Mason] settled on a mixture of silicon carbide, sugar, water, and alcohol for their susceptor.

The actual technique is pretty simple. A part printed in PLA is coated with susceptor. The part is then placed in a mold made of plaster of paris and perlite. The entire mold is cooked in an unmodified household microwave to burn out the PLA.

A second microwave with a top emitter is used to melt down aluminum, which is then poured into the prepared mold. When the metal cools, the mold is broken away to reveal a part ready to be machined.

We think this is a heck of a lot of work for a single part. Sometimes you really need a metal piece, though. Until metal 3D printing becomes cheap enough for everyone to do at home, this will work pretty well.

Cutting Records Out of CDs

3D Printed Record Lathe

Lovers of records rejoice! Did you know you can cut your own vinyl using something called a record lathe? [Beau Walker] just put the finishing touches on his 3D printed record lathe, and the results speak for themselves!

A Recording Lathe was once used for cutting records, and previously, wax cylinders – if you want to get really old school. [Beau], being an analog lover, decided he had to try making his own. He designed the whole thing in FreeCAD and got 3D printing. A single stepper motor drives the lead screw which moves the writing head back and forth as the record spins in place. As to not waste materials, he’s reusing old CD’s for his newly created vinyls. Two 25W speakers cause vibrations in the needle to cut into the disc, via a clever little mechanism.

The system works pretty well, but he wants to replace the turntable with another stepper motor for finer control of the recording — sometimes the turntable slows down during recording under load which messes up the sound. There’s a video of it in action on his site that we can’t embed here, so you should definitely go check it out!

Of course you could skip the middleman and go straight to 3D printing your records…

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