Nov 25, 2015 | By Alec

While 3D printed robots are commonplace all over the web nowadays, but those are often single purpose DIY creations that do what they were intended to do, but little else. Almost as a rule of thumb, they don’t look good or even close to life-like. Fortunately, a fun new project by Chinese filament developers Polymaker is proving that even animatronic robots – the kind that filled the amusement parks of our childhood – are well within reach of 3D printing, with an extremely flexible set of eyes that can look in any direction – just like you and I.

This new Eye Mechanism project is the type of fun and remarkably simple 3D printing endeavor that we love to see: with just a few non 3D printed parts and realized by taking your 3D printer and all those fantastic filaments to their limits. You’d be surprised as to what’s possible. As the developers explain, getting the most out of their filaments and 3D printers was exactly their purpose. ‘Our challenge was to design a 3D printable version of the animatronic eye mechanism. Obviously we would need some non printed parts, such as a couple servos and some nuts and bolts, but everything else could be 3D printed. By choosing a range of Polymaker filaments, you can create a very efficient system, with each individual part working beautifully alongside the next. The result is a captivating set of life like eyes,’ they explain.

What’s more, to help their 3D printing community, the good people over at Polymaker have made all the 3D printable files available for free and have developed an extensive tutorial to ensure that everyone can get to grips with 3D printing some more unusual projects and filaments. But, they ensure us, everything will be easily 3D printable on desktop machines, and all parts have been designed with quick and easy manufacturing in mind. If you’re interested, you can find the files on Thingiverse here.

The real animatronic power in this project comes from the two servo motors, which control the movement of the eyes, and two pivots – which copy and transfer the energy synchronising the eye movement. One servo is in charge of controlling in the left/right movements (or X movements), while the other takers care of the up and down (Y) movements – both are also optimized for use. ‘To get the full range of movement out of the servos and extend their lifetime, We decided to use a ball bearing to transfer the energy to both eyes. In this set up one servo is located right behind the eye and is directly driven by the motor. To enable both eyes to move in tandem, the second eye is linked indirectly and the power is transferred through a connecting rod and a bearing,’ they explain in their tutorial. ‘By using a bearing, it greatly reduces friction and ensures that the energy is transferred in a linear motion. The design of the Pivots has allocated space to encompass the 13mm bearing.’

Actually getting those bearing in the right place requires a bit of 3D printing ingenuity, as you have to pause your print around the 80 percent completion mark. Then just drop the bearing in the gap, and continue 3D printing – a clever technique for inserting a few non printed parts into functional designs. ‘Wait until enough plastic is built up around where the bearing is going before inserting the bearing. This will minimise the chance of your printer getting damaged by the nozzle dragging over the bearing during a travel movement. Once the print is finished you should have a well secured bearing in your 3D printed part,’ they advise.

That eye mechanism is then attached to the eyes through some clever PolyFlex couplings, that prove just what you can do when you forget ABS or PLA for a moment. ‘Only a flexible material can be used for this part. The part is designed to be flexible in every direction much like a universal joint, while still strong enough to push, pull and manipulate the eyeball accordingly,’ they explain. The infill used for 3D printing is crucial in getting the right flexibility, and in the end the PolyMaker team went for a 0% infill and two shells, which provided the perfect balance between between flexibility and stiffness. ‘Any more infill on the coupling and it started to drain power from the servos whilst limiting the range of movement. Any less shells and the part would delaminate at the stress points. It’s the shape of the coupling which provides the flexibility and an internal structure to stop it collapsing in on itself,’ they explain. This just shows what a bit of experimenting with settings can achieve.

But perhaps the most fun 3D printing decision was made in regards to the eyes. While you could 3D print a realistic eye in three parts and glue them together, Polymaker's Creative Technician Luke Taylor – who you can see in the tutorial below – actually 3D printed this in a single piece, using three different filaments. ‘For the base of the eye I used white PolyMax this is 85% of the print. As the white is reaching the top of the hemisphere, I paused the print to change the filament to PolyPlus translucent blue and then again to PolyPlus black to create a pupil for the final 4 or 5 layers (99%),’ he explains.

Once all the parts were 3D printed, assembly can really begin. ‘Start by inserting the long M4x45mm bolt through the 4mmØ stack in the corner of the board and secure it with a nut. Then screw another nut on top and leave it floating half way up the thread. This nut will be used as a shelf to match the height of the servo when levelling off your mechanism. Then repeat this step with the shorter M4x25mm bolt in the corresponding hole,’ Luke explains. The sockets are bolted to the board, as are the servos – taking care that they are differently mounted. ‘You may have to shave a small support of plastic off the bottom mounted servo to allow it to lay flat against the board. Make sure the orientation of the servo is correct. The centre of the servo arm should line up directly behind the socket. The Y Servo is bolted through the top of the board,’ Luke adds.

The wires are subsequently passed through a small notch on the board. ‘Once the servos are mounted in the board, plug in the wires and turn on your remote control. This will zero the servos and set them in their natural resting position. Make sure the trim on your R/C is also centred as you can use this to make fine adjustments on the rig when assembled. After zeroing the servos, choose the four armed servo arm and orientate the servo arm so it runs parallel with the edges of the board,’ Luke explains.

With that done, it’s a matter of assembling the 3D printed parts and bringing everything together. The eyeballs are attached with pins – that might need to attached with a heatgun. The couplings are attached to these pins, and to the conrods, pivots and servo arm extensions. ‘These all bolt together with the M2 bolts and the printed parts push fit together. Once you have all the pivots, conrods and eyes assembled, you can mount them onto the board. Start by clicking the balls into their sockets and then screw the servo arm extensions onto the servos,’ Luke explains. ‘Now adjust the floating M4 nuts so that your pivots and servos are at the same height from the board, the conrods and board should also be in parallel.  Secure the pivots with another M4 nut on top of the bearing and your eye mechanism is now assembled. Plug your servos and battery into your transmitter, turn on the R/C and make minor adjustments with the trim to centre the eyes.’

And that is, in a nutshell, what this project is all about. It might take a little bit of effort to synchronise the eyes, which you can do by pushing or pulling the couplings and pins into the correct position. The eyes can immediately spring to life afterwards, relying on nothing more than a handful of off-the-shelf electronics and getting the most out of a good selection of filaments. So why stick to that same boring PLA or ABS all the time? If you want to recreate this fun project, head over to Polymaker’s website here to find the complete tutorial

 

 

Posted in 3D Printing Application

 

 

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Hannes wrote at 11/25/2015 5:34:41 PM:

The thingiverse link seems to be broken



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