David Kitson builds Hybrid Petrol Electric bicycle

3D printing is not just a way to manufacture things, for some it’s slowly becoming a way of life. As it gives the power to create,back to the common man. For the past century or so we gave up ‘Making’ anything as we became used to the factory made products and goods, but thanks to 3D printing the culture of making is on a comeback. This long lost ability of the common individuals can bring across products that can change the way we live. David Kitson’shybrid petrol/electric bicycle is a great example of this.

Hybrid petrol/electric bicycle

David Kitson is a 46 year old man who lives in Australia;he is the writer of Turing Evolved a science-fiction novel that was ranked as the #1 best techno-thriller on Amazon in 2013 for 6 solid months. While going through the local junk yard last Christmas he found a bicycle in a pile of trash. He decided to repair it; he explains "Over Christmas, I found an old broken petrol-driven bicycle being thrown out on a rubbish pile. I repaired and rebuilt it and this introduced me to powered-cycling, which is fun, but the bikes had a lot of problems and ran off 2-stroke fuel which means you have to carry fuel with them. At some point, I decided the smelly and noisy bike could be improved on, so came up with the idea of a 4-stroke model, and then thought about making it a hybrid."

The Idea came naturally to David Kitson as he had experience with 3D printing while working on another project which involved making night vision equipment and developing military replacement parts. With his experience he knew that he would be able to make micro-sized generator parts with his Up Mini 3d printer.

Hybrid petrol/electric bicycle

Mr. Kitson added "So as the idea to build a micro-sized generator progressed, I needed to make a flange to hold an electric motor and a petrol one together to see if making a small generator for a bicycle was possible, as all the ones that could be bought were too heavy."

Converting the broken bike into a hybrid petrol/electric bicycle was no easy task; it needed endless hours of designing and prototype testing. He said after all the iteration to the original design, what he has is far better and economically viable than any other public transport available today. Talking about the designing and prototyping process and the challenges he faced while making the bike he said:

"Now my question from the 3D work with night vision came to mind and I wanted to know just how strong I could make a flange, and they got bigger and more complicated. Then I started printing internal structural parts. After a while, I said 'Hey, I can actually probably build this entire thing 3D printed, with just components bolted into it' and then it became a challenge on how to print something that large on the PP3DP UP Mini 3D printer. I went back to the drawing board, well, CorelCAD application, and when I finished, I had something that worked, but not well,” Kitson told 3Ders.

Hybrid petrol/electric bicycle

A few modifications though and it worked extremely well. Then I began working on how to eliminate everything that wasn't 3D printed and also that wasn't COTS (Commercial off-the-shelf) and succeeded with everything except the electronics components. It all slots together and I reduced parts count dramatically.”

Mr. Kitson wanted a bike that was not too costly and a mere proof of concept, he wanted the bike have a robust design and something that can be replicated with easy. To keep the cost of the bike and make it practical to use, he decided to not use batteries to operate the generator. He instead stuck with the tried and tested petrol as a fuel source; this increased the efficiency of the bike and also helped him keep the cost under control. He explained "Maintenance is simple and it gets me 25km (about 16 miles) into the office just as quickly as public transport or vehicles on heavy traffic days, yet at a fraction of the cost. Most importantly, because I don't have to over-exert myself, I don't sweat,"

Hybrid petrol/electric bicycle

Mr. Kitson also had to solve a unique challenge while developing the Engine for the bike; he was using ABS plastic to make the parts of the engine. Which made heat management inside the engine very critical, too much heat would melt the plastic and destroy the engine; hence he made arrangement for high volume of air to flow through to the engine to keep it cool. These small optimizations to the engine design ultimately helped him achieve perfection with the engine and generator dosing.

Mr. Kitson added "From that perspective, I guess I kind of just fell into it stage by stage," "I didn't know where the trip was taking me, I just wanted to play around, and before I knew it, each small discovery built upon the last until I had made it to a functional hybrid system that worked as I had originally envisioned. I found myself wanting to find a way to build a hybrid electric/petrol bicycle that people could order online, print parts at home and then assemble in about a few hours."

This trial and error method helped him design every single part from the actual internal combustion engine, the electronics and the generator core. The 3d printed parts in the hybrid bike includes lever arms on the throttle control box, air filter plates, electronics cover panels and the generator coverings.

He added “I also designed things in such a way that little support material was needed or had to be removed. That really helped, both saving plastic as well as reducing difficulty of manufacture. The engine mounts are 3D printed too. The motor just slides on and off the rear bicycle rack.”

“With this project, it will finally be possible for disabled people and people who cannot ride distances without assistance to use bicycles for touring, and to explore places and parts of our country that are not available to those with un-extended electrical systems.

With a range of 50km on a single tank, Kitson’s design is capable of travelling about five times what the top electric systems can at full power. "It would be suitable to around 80% of commuters that aren't strong or fit enough to ride a bicycle a long way." Kitson said. "Unlike the European standard bicycles, the full system I developed will actually add it's power to whatever you put in, so the benefit of pedaling is that you get there quicker and you can take a break whenever you need or want."

The robust design of the bike and feasibility has been certified by the Western Australian Department of Transport. Boasting about this Mr.Kitson added "The system conforms to the EN15194 standard as well (Clip-on charger exceptions) so should be legal in most of the world. It also meets safety and emission standards for small motors, so the applications to which it can be put are far beyond small bicycles."

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