Recycling Plastic With Liquid Nitrogen

March 29, 2014 by 26 Comments

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Recycling 3D printer filament isn’t a new idea, and in fact there are quite a few devices out there that will take chunks ABS, PLA, or just about any other thermoplastic and turn them into printer filament. The problem comes when someone mentions recycling plastic parts and turning them into filament ready to be used again. Plastics can only be recycled so many times, and there’s also the problem of grinding up your octopodes and companion cubes into something a filament extruder will accept.

The solution, it appears, is to freeze the plastic parts to be recycled before grinding them up. Chopping up plastic parts at room temperature imparts a lot of energy into the plastic before breaking. Freezing the parts to below their brittle transition temperature means the resulting chips will have clean cuts, something much more amenable to the mechanics of filament extruders.

The setup for this experiment consisted of cooling PLA plastic with liquid nitrogen and putting the frozen parts in a cheap, As Seen On TV blender. The resulting chips were smaller than the plastic pellets found in injection molding manufacturing plants, but will feed into the extruder well enough.

Liquid nitrogen might be overkill in this case; the goal is to cool the plastic down below its brittle transition temperature, which for most plastics is about -40° (420° R). Dry ice will do the job just as well, and is also available at most Walmarts.



            


    



                    
                    
                
                    


        

        
Energy-Saving Fireplace Thermostat

                

            March 29, 2014 by 
            
                6 Comments            
        

        
    


    

        


[Andrian] has a boiler stove that heats water and sends it to a radiator. As the fireplace heats the water in a boiler a temperature sensor opens the a valve to send the warm water to the radiator. The radiator sends its cool water back to the boiler to be reheated. The valve is slow, so before the boiler can send all the water to the radiator, it’s getting cool water back causing the valve to close while the heat is built back up. To prevent the valve from working so hard and wasting energy, [Andrian] designed a better thermostat to control the valve operation.


The thermostat uses one LM85 temperature sensor to check the water in the boiler and another one for the ambient temperature. Once the boiler water reaches the desired temperature, the valve is opened via relay. The system waits for half an hour and then checks the boiler temperature again. The brains of this operation is an ATMega168 with a 32.768kHz crystal as the RTC. Code and PCB files are available in his repo.


We love to see these types of hacks that challenge the status quo and increase the efficiency of appliances. We applaud you, [Andrian], for turning your dissatisfaction into a positive plan of action and for sharing your experience with the rest of us!


If you want to up the eco-friendliness of heating water a bit, you could heat the water with a compost heap.


            


    



                    
                    
                
                    


        

        
Successful 3D Printed Cranium Implant

                

            March 28, 2014 by 
            
                43 Comments            
        

        
    


    

        
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What an age we live in. If the image above looks like the entire top of a skull — it’s because it is. Surgeons successfully replaced a 22 year old woman’s cranium with this plastic copy.


We’ve seen small 3D printed transplants before, but nothing as big as this. A 22 year old woman suffered from a very rare disorder in which her skull never stopped growing. While normal skulls are about 1.5cm thick, hers was almost 5cm thick by the time of the surgery. If they left it any longer, the continued bone growth would have eventually killed her.


Until now this surgery has required a hand-made concrete-like implant to replace the removed bone. As you can imagine, it’s hardly an ideal solution. Thanks to continually advancing 3D printing technology, surgeons at the University of Utrecht UMC were able to create an exact copy in a durable and lightweight clear plastic, which also has a better rate of brain function recovery than the old way of doing it.


The 23 hour surgery took place last December and was a huge success with the patient making a full recovery — if you’re not too squeamish around exposed brains, check out the following video. Wow.


 Continue reading “Successful 3D Printed Cranium Implant” →


            


    



                    
                    
                
                    


    

    

    

        
The Amazing Ping-Pong Robot Was Fake

                

            March 28, 2014 by 
            
                44 Comments            
        

        
    


    

        
Well — you guys were right. As it turns out, it was actually a pair of animators who fooled the internet.


Not sure what we’re talking about? Last month, the [Kuka Robot Group] put out a highly polished video showing an industrial robot playing table tennis against the apparent world champion of the sport — it was extremely well done and entertaining to watch, but unfortunately… also fake. Weeks after the first [Kuka] video came out, someone named [Ulf Hoffmann] released another video, a small table tennis playing robot that looked almost feasible.


As some of our readers pointed out:


The movements seemed unnatural for the size of the servos and arm structure. ~ James


CGI. As others have pointed out, the shadow of the arm disappears when the robot is show from the side, even though they were added in the other shots. ~ Brandon


My cgi tip off was the cable under the table. It stretches instead of sliding around. ~ Aj


Notice it’s running Outlook Express and Internet Explorer – no self respecting hacker/maker would run those apps – lol. ~ vonskippy


 Continue reading “The Amazing Ping-Pong Robot Was Fake” →


            


    



                    
                        

                            
                        


                    
                    
                
                    


        

        
Rock Out With Your Ribbon Controller Bass

                

            March 28, 2014 by 
            
                10 Comments            
        

        
    


    

        
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[Brendan Byrne] stripped this instrument down to basics and built himself a ribbon controller bass guitar. Details are still a bit sparse  on his website, but there are plenty of detailed pictures on his flickr stream. [Brendan] built his bass as part the Future of Guitar Design Course at Parsons the New School for Design. His goal was to create an experience in which playing the instrument and altering parameters of effects are triggered by the same gestures. He’s definitely succeeded in that effort.


Basically, the bass is a four channel ribbon controller. The frets were removed to make way for four graphite strips. [Brendan] followed [Iain’s] excellent tutorial to create his own graphite strips using soft artist’s pencils. The ribbons essentially become potentiometers, which are then read by a teensy. [Brendan] expanded the instrument’s sonic palette by adding several buttons and potentiometers mapped to MIDI control codes. He even included a triple axis accelerometer so every movement of the bass can be mapped. The MIDI data is sent to a PC running commercial music software. Analog sound comes from a piezo pickup placed under the bridge of the bass.


The results are pretty awesome. While we can’t say [Brendan’s] demo was music to our ears, we definitely see the musical possibilities of this kind of instrument.


 Continue reading “Rock Out With Your Ribbon Controller Bass” →


            


    



                    
                    
                
                    


        

        
Sci-Fi Contest Prize Acquisition Issues — Oh Noes!

                

            March 28, 2014 by 
            
                35 Comments            
        

        
    


    

        
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We spent quite a bit of time picking out prizes for the Sci-Fi contest. But wouldn’t you know it, literally the day after announcing the contest we cued up The Amp Hour and heard about a worldwide stock shortage (34:00) of BeagleBone Black boards. About a week later Adafruit ran an explanation of the issues. It became clear why we were having issues sources a quintet of boards so that we could deliver on our prize offer.


To further compound problems we a somewhat smaller issue sourcing Spark Core boards. We put in an order for a quintet of them when we posted the contest; at the time they were supposed to be shipping in late March, but now shipping estimates have been delayed to mid-April. Assuming no more delays these should be available by the time the contest ends at the end of April so keep your fingers crossed.


We have a good relationship with the folks over at Spark Core and can probably ask them to help us out if we do get in a bind. But we don’t think anyone is going to be able to deliver the BeagleBone Black boards (which we have on backorder) in time for the end of the contest. So here’s the deal: if you win and really want these exact boards in the prize package you select, we’re going to do what needs to be done to get it for you, eventually. If you don’t want to wait and there is a suitable alternative we’ll make that happen.


We wondered what people are doing if they don’t want to wait out these shortages. Are there any other open-hardware projects that are similar in price and functionality? Our gut says no (that’s why they’re in such high demand). But we’d love to hear about some alternatives. Let us know by leaving a comment below.


            


    



                    
                    
                
                    


    

    

    

        
High Tech Convertible Desk Takes It Up A Notch

                

            March 28, 2014 by 
            
                17 Comments            
        

        
    


    

        
Standing desks seem to be all the rage today — but do you really want to commit fully to always standing? [Jeff Minton] didn’t, and when he found out how much convertible standing desks cost… he decided to make his own.


While brainstorming ways of accomplishing this he started browsing around eBay and found 18″ linear actuators for sale. They were $45 each, ran at 24V and could lift 600lbs each. Bingo. Actually, that’s kinda overkill…


He picked up a 24V power supply, an Arduino, and a 8-channel relay board.  The actuators are attached to the desk’s original legs using U-bolts which keep the legs straight and take the load of the desk. The untreated wood supports are there to reinforce the original desk, because they weren’t that sturdy in the first place.


It takes about a minute to fully actuate the legs, so while it’s not the prettiest nor the quickest solution — it does the trick and allows you to easily switch between standing and sitting.


 Continue reading “High Tech Convertible Desk Takes It Up A Notch” →