Saturday, February 7, 2009

project: wheel continued



I believe when i last left off i had flipped the fork over, finished welding a new base onto it and the mill was even floppier than before. It kept falling off to the side (as you can see in above photo).

Well, i came back to it a couple of days ago with fresh eyes and tried to figure out what to change.

The first thing that i did was to switch the stem with pivot around, i hadn´t done this when i flipped the forks over. Considering that the angles of both the pivot joint and corresponding drilled holes in the neck of the fork were a little wonky, i thought it might make a difference. And it did. Though not perfect, it definitely stabilized some when i reattached the two pieces as Will made them.



It was sitting well enough that i thought i would give it a go. Palo was conviently wanting some coffee ground, so we killed two birds with one bike.


video

It was a little too loose at first, Carlos showed me how to tighten it and voila, Palo had delicious freshly ground coffee.


The next logical step was get the whole unit sitting lower. Although effective, it was a little ridiculous to pedal the bike by hand. Lowering the seat would allow me, and your average Guatemalan, to use leg power- a more powerful and ergonomical arrangement.

I think i mentioned it in a previous post, but if i didn´t, my first thought to get the whole unit sitting lower was to ditch the wheel, but keep the hub (the hub being the epicenter of the wheel where the spokes all attach and the axle is). My plan was to wrap the hub in rubber so that it would function like the liquadora.

The first thing to do was pop off the wheel. Next i had to remove the tire and inner tube. The air had to be let out of the tube, and then i used these little pry things to convince the tire off. I think they are called tire levers, or leveragers? Is leverager is a word. I don´t think so, but we can pretend it is.


And separated like so...






Then the spokes had to be removed using this thing- called a spoke key in spanish, i think spoke driver in english. The key is used to unscrew the spoke nipples, yes, nipples. The nipples are reverse threaded, or another way to think of it is that they are correct threaded if you view them from the inside of the rim. Like this:



Once removed, the hub looks like this. The box its sitting on top of is the nipple bin. That´s where all the nipples go, courtesy of Anneliese´s awesome organizing around the shop.



I took all of the spokes out, tedious for sure, but not nearly as tedious as removing one when the rest are still attached to the rim.

Then, just for fun, i put the hub back on to see how much lower it would be.



Pretty big difference. The seat could now sit where it should.


Seeing the hub like this gave me a thought about the rubber. What if the rubber were shaped to conform to the wheel? It would increase the surface area, and therefore pull, and it would also serve just to keep the darn thing from falling off to the side.



On the roof there is this big tractor tire, Carlos uses it for exactly this type of thing. He was fine to have us cut into, just be mindful of the metal (i didn´t know tires have metal mesh in them). We cut from the side, since it seemed to be the place with the least metal. (oh, i´m saying we and us becuase Erin has joined me at this point).

However one poor go with the drill was enough to convince Erin that there were better things to do. (She broke Carlos´homemade hole saw) I suggested she try again with a different strategy, it wasn´t her fault the bit broke, it was weak and would have happened to either one of us. But she had her power tool fill for the day. There goes we.

I cut out several circles and ground them to a flatter state. I then drilled small holes in the center of them and cut them apart so they would wrap around the hub (leatherman strikes again!)



Once on the hub they looked like this:



Alas, they didn´t work. They were just spinning in place, not moving the hub at all. They needed to be attached, and in a flash i had the perfect idea! The hub, needing to hold spokes, is lined with holes. Why don´t i drill holes through the rubber and tie wires through? That´ll do it for sure.

Well, drilling accurate holes in the rubber was pretty difficult. Really it just didn´t work at all. So in a Carlos-esque move i thought, why don´t i get a sharpened spoke red hot and just jam it through the rubber? (Something OSHA never would approve) (they never approve the fun stuff)

So i did.

In a word- awesome. Okay, two words- awesome & ineffective.

I took the whole thing mostly apart, ground down some spokes and got to it.







After way too much time of not being able to get the molten spears from one end to the other i began to consider other options. Also the stench was probablly getting to the others in the kitchen, "you´re wasting gas" they told me. Yeah yeah, you just don´t like my tire stink. Weirdo.

It took me some time, but eventually i figured out that the holes don´t actually line up. They are slightly angled from one another. Also to get the spear through it also had to hit the right height. There was enough play in the whole system that it would be pretty difficult to actually poke it in one end and get it to come out the other. To compound this, i could only come from one side as the welded-on gear was most definitely in the way. (I tried to make a right angle spear to get around this, to no avail).

Once the novelty of the crazy plumes of rubber smoke, which seemed to stick to the hub like magnents ( so cool, you gotta try it), i decided that this method wasn´t going to work. At least not without consulting the maestro. I tried to melt the rubber onto the hub some, and to a degree to the other pieces. It seemed like it worked, but a test run proved otherwise.


I reattached all of the parts to the hub, then used the metal grinder to carve out the shape of the wheel. On the bike it looked like so:


Okay, so what else can we grind? Cocoa beans!


And in action, here it is:


video


The mill, couldn´t be too tight (as tight as it need to be for a good grind) or it simply wouldn´t work. It functioned, but poorly. Its funny, in the video you see the chain hopping all around- turns out it wasn´t even on the gear but it still worked- i have no idea how.

Tightening up the mill would wreck the rubber set up.


And also, the chain kept getting strangely stuck. Upon examination i found that it was popping off of the chain ring on the mill and getting caught between the ring and the barriers on it. Fixing this involved some fine tuning with a wrench. The walls couldn´t be too tight or they would totally constrict the flow of the chain, but they couldn´t be too loose or the chain would fall off and get caught.


Once i got this all settled it, the rubber was still a problem. Yarrgh! If only my pyromaniacal scheme had worked.

A few days earlier i had spotted a little tire, probablly the tiniest in thewhole mess of bikes. It would be a middle ground between the rubber covered hub and the original wheel, probablly requiring the seat to come back up some. I´ll give it a go, but its already ripe with new challenges, namely that ther are no inner tubes its size- i´ll have to construct one manually.

I may just scrap the whole tire, rubber bit entirely. Plan C is already stewing in my mind, though i don´t think its a design a north americans will like. Yet.

The new tire compared to the previous one.

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