Gas Powered Longboard

http://www.youtube.com/watch?v=uUymo7rTnZg

     So after last winter semester I had two weeks before starting the summer term. With Maria still in work it was up to me to entertain myself. Honda sells its 200cc horizontal shaft engines for about $350 but I found out that Harbor Freight sells a clone of that engine for $160. Right before my break that same engine went on sell for $100, and with a coupon you could pick it up for $80. I could do an entire blog post about the good, the bad, and the ugly of Harbor Freight, but needless to say, an $80 engine gets my mind working. I picked one up and brought it home and started making plans. The problem was I only had one engine and couldn't decide what to throw it on! I could put it on my commuter bike, I could put it on the recumbent, or the tandem bike, make a go kart, or throw it on our long board. They all sounded like fun so I started thinking of a way that I could do them all. What I came up with was kind of a modular idea so I could quickly change it up. I decided the easiest way to do this was as a kind of a push trailer that could be easily attached to various objects.

Most of the parts I needed could be found from gokart supply stores, but ended up being a lot more than I was willing to spend on the project. The only part I ended up buying was a centrifugal clutch (it disengages the chain under a certain RPM so the engine can idle at rest). The centrifugal clutch has sprocket teeth on it that are made for a wider chain so they had to be ground down. I put the clutch on the engine shaft and fired it up, I now had a makeshift lathe! Using a grinding stone on the angle grinder I was able to uniformly grind the spinning teeth down so they would fit a bike chain. My cousin Mark Hsiao was nice enough to give me some extra wheels he had lying around, I used one as the actual wheel and ripped the hubs out of another two wheels and fab'd some adjustable mounts for them so i could use them as bearing mounts for the live axle. I made my own simple frame to hold it all together and welded a bike sprocket to the axle for a simple drive line.

It has a trailer hitch on the front that can easily be attached with different configurations. I wanted something original so I decided to start with the longboard which ended up looking like this.

The handle has a throttle, brake, and kill switch. 

Put it all together and this is what you get->

http://www.youtube.com/watch?v=uUymo7rTnZg

It made for a pretty exhilarating ride. The engine probably has enough power to get someone going over 60 mph, but the way I did the gear ratios it limits it to about 30 mph. If you don't think 30 mph sounds fast trying doing it on a squirly longboard. I asked Maria what we should call it and she just said "dangerous," understandably she was never a big fan of this particular project. I am still open to suggestions for a cool name, I am pretty sure we can do better than "gas powered longboard". Anyway, the back tire doesn't really get enough weight on it so traction is limited and makes it that much more squirly. Regardless, it is a blast to ride and there is just something special about bombing a longboard uphill.

Egg Bike

          So this is a project that I planned to start months ago. The idea is that you have a bike where the rear wheel hub is slightly offset from the center so it wobbles like an egg, and if you pump your legs just right you can propel it forward. So there is no chain, no pedals, no crank hub, no seat, should be quick and easy right? The tricky part is making a wheel with an offset hub which means making new spokes, each with a custom length, maybe by cutting and re-threading the ends or by welding segments together. But how long would each spoke need to be? I sat down to do the math... and i sat... and i sat...turns out I haven't taken an actual math class since 11th grade about 9 years ago and it was totally over my head. The math included variables for the inner diameter of the wheel, but also the outer diameter of the hub, and the fact that left and right sets of spokes are not co-planar so you have to consider the hub width. Anyway, I have been known to pull out my old TI-85 on projects occasionally, but this one had me stumped. Fast forward several months and i decided to email my brother-in-law Matthew, one of the most overqualified people i could think of. I sent him the measurements and this is what I got back the next day:   http://maffoo.net/EggBike/   Thank you Matthew for the idiot proof app!

    That taken care of, I proceeded to do what I do best, chop up old bikes. I started by stealing spokes off of a larger wheel. Spokes are actually threaded at the ends where a nipple(basically just a special shaped nut) bolts them to the rim, they require a special tool that i am sure you can buy somewhere but it was a simple fabrication job so i made this up real quick

These are also useful on normal bikes that have a bent wheel, you can adjust the spokes accordingly to straighten or "true" the wheel.

Using the Matthew's app i was able to make each spoke just the right length, i decided the easiest way to do this was to measure it off with it clamped in the vice, then hammer it over so it bends down right at my measurement.

   With the spoke threaded into the hub, i would then bend the spoke the rest of the way over so it was locked in, i could then trim back the excess.

Now time for the bike frame! I found a front fork off of a larger bike that was deep enough to accommodate my lopsided wheel and decided to simply attach it to the front end of a small bike. The frame of the smaller bike had a very thin gauged metal, and most of its structural strength comes from its shape. I didn't want to lose the strength of the larger tube by welding it directly to the smaller stem of the front fork, so i used this square section of steel as an intermediary. The other difficulty of welding thin gauge steel is that it doesn't have the mass to absorb the heat of welding. When you try to weld it it gets so hot that it simply gets blasted away. By using the thicker square section it acts as a heat sink making for an easier and stronger weld, it also makes for a nice surface to hammer the bike frame onto for nice adaptation.

The "front" fork is now ready to be added, nothing complicated here

Voila! It has that 3 different colors Frankenstein look, but a coat of paint could go a long way.

It takes a bit of practice to ride, you have to be able to feel the rhythm, but the neighborhood kids love it and have been over every day to play on it.

Here is the finished product in action

http://www.youtube.com/watch?v=qUKmhPg9knw

The Orange Garage

The day will come when no level of organization will be able to contain the junk in my garage and I will have to start thinning things out. I thought I would start documenting some of my creations in preparation for that inevitable day and maybe take comfort in knowing that they still exist in some share-able form. It makes me think of other creations and projects from my youth that have long since been clutter controlled by my mother and are probably buried in a landfill somewhere. This will also be a nice way to share what I have been up to for those who occasionally ask "what have you been working on lately?".
I thought it would be fun to post current projects along with some description of the processes and methods used in building which may at least be of interest to the technically curious. In addition I think I will start sharing older projects I have completed. Some were well documented and may still be lying around somewhere, others (the landfill variety) are nothing more than old blurry photos at this point but still may be worth sharing. For those with zero interest in anything that happens in a garage, I will probably still be sharing pics from recent adventures and whatever else my lovely wife and I have been up to, even though she has that pretty well chronicled on her own blog http://miafran.blogspot.com. With any luck I may be able to inspire a few to ditch their computers for an evening in the garage and begin their own creations, and hopefully spark some discussion for improvements and new ideas. Thanks for reading!
-Rich