Hinge Concept to Make Movable Toys with a 3D Printer
It’s quite fascinating that with a 3D printer, a flat printed toy is able to move after being taken off from the print bed without any after assembly. How is that possible? The answer is that a hinge concept which combines the use of gaps and bridges makes it possible. Let’s go further with Mr. Irv Shapiro, the author of the DrVax YouTube channel, to unveil the extraordinary ability of the desktop FDM or filament style 3D printing technology.
Mr. Irv Shapiro shows a 3D printed scissor-like device.
Fascinated by the 3D printed movable toys from his grandson, Mr. Irv Shapiro decided to share his ideas with his understanding of the hinge concept to make movable 3D print devices.
What is hinge concept?
Hinge concept is an idea to design with gaps between parts and bridges that connect posts and finally make a hinge like device which is movable for playing fun.
Bridge is to extrude filament from one post to the other and connect them like a bridge. Your 3D printer might extrude 10 millimeters, 30 or even 40 millimeters bridge which depends on its performances. Bridges work as lintels on the top of windows. And also it’s important to leave gaps below.
The second important thing is to stop extruding and leave gaps horizontally or vertically to keep spaces necessary for moving the parts.
The key to create hinge like devices is to have a middle component with gaps circled around. It makes the device movable.
Flexible butterfly designed at hinge concept
Test extruding accuracy of your 3D printer
As we can see in above picture, layer number one has two gaps between three layers. And the size of the gaps is critical for making a hinge like device and it mainly depends on the extruding accuracy or the tolerance of your 3D printer. You can print below things on Thingiverse and test your 3D printer.
There are five holes on it. By inserting individual peg for each hole, you can check if the holes contain the pegs at the marked gap values. And through it, we know filament extruding tolerance of your 3D printer.
A 0.2mm gap is sufficient to allow clearance for movable components printing.
What factors would impact the success of printing movable devices?
There are four factors including bed temperature, extruder multiplier (or flow on Cura), printing temperature and speed that would impact the success of printing movable devices.
A scissor device fused at the bottom layer
- As we mentioned above, every print starts at the first bottom layer. This layer adheres to the print bed. Bed heats up during printing and if it goes too hot, it would melt the first layer a little soft. Thus the layer spreads as blue line showed and even connects together.
- The second factor is inappropriate extruder multiplier settings in Prusa slicer which is also called flow in material section on the Ultimaker Cura. Extruder multiplier settings decide how much filament should be extruded from the nozzle. If you have a 0.4mm nozzle on your 3D printer, you’re likely to take a 0.4mm filament extruding as granted. But actually calibration of stepper motors or other things can lead to inappropriate filament extruding. Fox example, if the extruding is a little too much, you can set extruder multiplier (on Prusa) or flow (on Cura) to 0.95 or 0.90 to extrude less. And it’s better to set that for the first layer because it often spreads a little. On some advanced slicer, you can even set extruder multiplier per layer.
- The third thing is the printing temperature. If the printing temperature is too high, the filament will be softer and spreads. Severe filament spreading tends to fill gaps and stick together. And if the temperature is too low, horizontal adhesion between layers will be not good and results in layer shift. So you should calibrate printing temperature setting for a better filament extruding on your 3D printer.
- The last thing that affects the print of movable devices is the printing speed. The faster the printing goes, the more the printer vibration happens. Vibration cause the printer extrudes filament onto inaccurate positions and affect gaps on movable devices. Thus, lower down printing speed also helps to increase the rate of successful printing a movable device.
Additionally, cooling is the fifth factor. Faster cooling of layers can prevent bridge parts from drooping down.
3D printed fidget spinner
Now you can use above tips and print some interesting devices like snakes, scissors, spinners, geared heart, and etc. Thanks to Mr. Irv Shapiro for his marvelous video about how to print movable devices. From his clear instruction about the hinge concept of 3D printing, we’ve learned a lot about printing movable toys with a 3D printer.
Make 2015 Shootout Tests — including the tolerance test
Flexi Dragon — Not in this video but another print I really like
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