Despite having identical gear ratios to, and smaller drive wheels than, my previous "rolling chassis" designs ("Spring Motor Rolling Chassis Version 2" here: http://www.thingiverse.com/thing:2011107, and "PLA Spring Motor, Rolling Chassis" here: http://www.thingiverse.com/thing:430050), the Dual Mode Spring Motor Rolling Chassis out distances both thanks to it's dual mode operation.
The first mode is identical to the previous two rolling chassis designs, using a PLA spring motor to power the chassis. The second mode is new, "true coast". As opposed to the previous two designs which depended on a weak pawl to release from the pawl gear for coasting, (which, due to friction, limited the distance these vehicles would coast), true coast utilizes a floating pinion gear (I published a floating pinion demonstrator here: http://www.thingiverse.com/thing:2025927). Under spring motor power, the rear axle is connected to the spring motor via the floating pinion gear and the torque from the spring motor. When the spring motor energy is depleted, the floating pinion disconnects from the rear axle via the rear axle gear pushing the pinion back to it's parked position, allowing the rear axle to free spin and the chassis to truly coast.
Video of the prototype is here: https://www.youtube.com/watch?v=-DkAy472jlo.
Video of a comparison between the "Spring Motor Rolling Chassis Version 2" and the "Dual Mode Spring Motor Rolling Chassis" is here: https://www.youtube.com/watch?v=PjmT369N0wM.
The two photos are first, the actual prototype, and second, the output of Fusion 360 (without the o-rings).
You will need to purchase four AS 568 #213 o-rings (1 3/16" O.D., 15/16" I.D., 1/8" diameter) and eight AS 568 #223 o-rings (1 7/8" O.D., 1 5/8" I.D., 1/8" diameter), which are available on line, and at plumbing supply / box stores.
Designed using Fusion 360, sliced using Cura 2.3.1, and printed in PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.
Print "Knob and Axle.stl", "Chassis Left.stl", "Chassis Right.stl" and "Spring.stl" with 100% infill, the remaining components with 50% infill.
Print two each of "Wheel Front.stl" and "Wheel Rear.stl", print one each of the remaining parts.
Prior to assembly, test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding may be required.
Study "Assembly.stl", carefully noting the locations and positions of the various components as assembly proceeds.
1) Press "Gear Axle Rear.stl" onto "Axle Rear.stl".
2) Press "Gear Idler Small.stl" onto "Axle Gear Idler Small.stl".
3) Slide "Knob and Axle.stl" into "Chassis Right.stl", then press "Spring.stl" and "Pawl.stl" onto "Knob and Axle.stl".
4) Slide "Gear Pawl.stl" onto "Knob and Axle.stl".
5) Slide "Gear Idler Large.stl" onto the axle on "Chassis Right.stl".
6) Place the idler assembly ("Gear Idler Small.stl" and "Axle Gear Idler Small.stl") and rear axle assembly ("Axle Rear.stl" and "Gear Axle Rear.stl") into position in "Chassis Right.stl".
7) Press "Chassis Left.stl" onto "Chassis Right.stl".
8) Place the o-rings on the wheels.
9) Press one each of "Wheel Rear.stl" onto each end "Axle Rear.stl".
10) Position "Axle Front.stl" into the chassis assembly, the press one each of "Wheel Front.stl" onto each end of "Axle Front.stl".
Hope you like it!
Spring Motor Rolling Chassis Version 2
PLA Spring Motor, Rolling Chassis
Floating Pinion Demonstrator
The more mistakes I make, the more knowledge I gain.