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Picture of How I Designed a 3D Printed Windup Car Using Autodesk Fusion 360.
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I've designed, 3D printed, assembled, tested and published quite a few PLA spring motor floating pinion cars and demonstrators over the last few years, so why would I design, print, assemble, test and publish yet another one?

Well, "How I Designed a 3D Printed Windup Car Using Autodesk Fusion 360" includes a four part video series detailing how I designed this 3D printed windup car (with floating pinion drive) using Autodesk Fusion 360. And I've also included the Autodesk Fusion 360 cad file "Windup Floating Pinion Car.f3d" containing the completed design (familiarity with the Autodesk Fusion 360 environment is highly recommended, and if a discrepancy is found between the videos and the cad file, use the cad file).

So if you're interested in my design process for a PLA spring motor powered windup car with floating pinion drive, and / or wish to modify the design to create your own custom version, then this Instructable may indeed be of interest to you.

And if you're simply interested in 3D printing and assembling the car, I've included all STL files required to print the car, along with preparation and assembly instructions.

And finally, what's a floating pinion? In this design a floating pinion is a pinion gear that traverses a guide slot, engaging the PLA spring motor with the drive axle when spring energy is present, and disengaging the PLA spring motor from the drive axle when spring energy is depleted. By disengaging the PLA spring motor from the drive axle, the car is allowed to coast, as opposed to abruptly stopping, when spring energy is depleted providing a significant increase in travel distance.

And as usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to ask as I do make plenty of mistakes.

Designed using Autodesk Fusion 360, sliced using Cura 4.0, and printed in PLA and Tough PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.

Step 1: Designing the Spring Motor.

The spring motor consists of the "Knob.stl", "Spring.stl", "Pawl.stl" and "Gear, Pawl (24, 2.2).stl". The knob is used to wind the spring, and the pawl and pawl gear provide the ratchet mechanism for winding.

As with all components of this model, I design using what I call "sketch in place" which keeps the sketch in position with the extruded component for easier editing.

The pawl gear, as with all gears used in this model, was designed using a module of 2.2. There are only two gear sizes used in this model; twenty four and eight tooth. For a twenty four tooth gear, the pitch radius is ((24 * 2.2) / 2) or 26.4mm. For an eight tooth gear, the pitch radius is ((8 * 2.2) / 2) or 8.8mm. These dimensions will be used in the next step.