peak moment

While I was still down in Guatemala I got in touch with Peak Moment, a television show covering peak oil issues, and told them about what i was up to. We kept in touch, and late in the summer of '10 they came out to Aprovecho and filmed several shows.

If you do any research on peak oil, you'll eventually end up watching an episode of Peak Moment, and for good reason- they do some really excellent programing on local self-reliance and creative responses to peak oil and climate change.

It was nice finally meeting Janaia and Robyn, and it was great to film a show with them. Here it is:

While they were at Aprovecho they filmed several more episodes, so keep an eye out for those as they may be showing up soon. And be sure to check out Peak Moment's youtube channel, there's a lot of great information out there.

straw chopper 6

Once both ends of the container, lets call it the hopper, had been put together it was time to weld some bracing between them.

 

I tacked a temporary brace between the two ends, in order to keep it straight and true, and then welded in one of the supports for the top. Then the next.

  

After that came the two pieces that would hold the grate in place. 

  

The grate, a metal mesh i found, would serve the purpose of filtering the straw. Once the straw was chopped finely enough, it would pass through the grate into a container below.  Until then, it would swirl around inside of the container. I was pretty proud of the mesh, frankly. Because i thought it a good idea, but also because there happened to be this one random piece of metal that was rusting away and bent out of shape that i managed to save for the job. It took some pounding with a hammer, some bending, some wirebrushing, but it turned out pretty nice. 

 

  

The best part was that it fit in the frame perfectly. It fit so well that i didn't even need to weld it into place, its natural tension kept it snugly put. This was a big relief, i was concerned about welding it. Another perk of the tension fit was that it was then removable, making the whole thing easier to clean, access, repair. 

At about roughly the time that i was finishing this portion of the machine i undertook a large side project- renovating the shop space. I'll retain the details of that for a later post, save that it took a very long time- maybe a month or two. And somewhere in there Chris, the natural builder who proposed the straw chopper, let me know that the machine was taking too long. The deadline in mind was a natural building workshop, the idea being that the chopper would be used to chop the straw for the workshop. Get it done, i was told. Fast. 

I understood the need to finish the project, it was definitely taking too long. Though it was disappointing to let go of trying to make the thing look as clean and nice as possible. No more energy would go into joint design or hiding welds, only pure function mattered. 

 Since i had the hopper more or less finished, i needed to build (or find as it were) a container for the chopped straw to fall into. Also, to create a structure for pedals, a wheel and a rear derailleur. 

I found this big blue barrel out in the scrap yard- it was perfect. 

I welded a frame to fit around the top. I made it tight enough that it would fit snugly, as opposed to welded on, and therefore removable. Next i made a stand to permanently affix a bike wheel to, and for the barrel to sit on top of.

 

 

 

The bike wheel, if you didn't see from previous posts, will act as a pulley. A thin belt, taken from a clothes drier, goes around it and runs the lawn mower blades. Below i have it mocked up for placement. The primary thing that i was trying to figure out was the distance beyond the edge that the hopper would have to sit. 

Once i had the placement set i propped up the back end with whatever i could find and welded two supports in place. 

Then i constructed a support structure to hold up the rear. Because the backside of the hopper didn't quite reach the end of the barrel, i had to run a piece of angle iron across the gap. 

Next, i welded on a small tube into which i could insert a belt tensioner. In fact, the tensioner from the very same drier that the belt came from. There are several reasons that a tensioner is important- first because it puts the proper amount of tension on a belt for it to drive well, while still keeping it flexible enough to remove the belt when necessary. Second, belts (as well as chains) stretch over time, and a spring tensioner will automatically adjust for that. 

With the pedals, i just needed a simple structure to hold the cranks up at a good height. Really, all it had to be was a bottom bracket welded onto a post.

In order to determine the height that i wanted the cranks to be i performed, what has come to be known as, the "brad and heather test." Brad is really tall, heather really short. The perfect test for height compatibility.

Everything checked out fine. I figured out that i could leave the pedals at their current height so long as the seat extended greatly and was also not attached to the structure.

In addition to having a tensioner on the belt, i would need to put one on the chain as well. Though there wouldn't be a need to change gears, the second function of a rear derailleur is to act as a tensioner. I had plenty of those lying around, so i grabbed one that looked good and tacked it on to the frame. 

 

  

You'll notice extending from the pedals to the right is a new long piece of angle iron. I had to put that in there because the machine kept creeping forward away from the pedaller. This way with the seat on top of bar the weight of the pedaller would keep the whole thing still. 

At this point it was pretty much time to wrap it up, everything was connected, the gear ratios felt great- the blades spun like a whirlwind. My initial thought was to seal in the hopper with sheet metal. But it occurred to me while building it that it would be much nicer to be able to see into the hopper. Seeing the result of your labor is the majority of the fun of human powered machines. At least it is for me.  

At one point there was this guy Ash (talented natural builder, all around great guy), he bought a truck and had the rear windows taken out because they were plexiglass. I remember asking him if i could hold onto it because i figured it might come in handy. And indeed it did. There was just the right amount and just the right size to enclose the hopper with it. 

To close up the bottom i used sheet metal, easier than the plexi, plus i needed the flexibility of the metal to create an angled and curved shoot to direct straw into the barrel from the overhang.

Both the plexiglass and the sheet metal were glued in using epoxy. Unfortunately, even with roughing the surfaces and using clamps they still fell out periodically. With the sheet metal, welding it in with stick wouldn't have worked. Tig could have, even mig. But those weren't options. The plexiglass could have been bolted in, but that would have meant more work and more expense. Time and money were against me. 

There were a couple final touches to make before it could be officially pronounced finished. I had to have a seat that could lower and raise, yet be independent of the rest of the machine. I also needed handle bars. And, as it turned out, the whole thing would fall toward the rider (not sure why) so i had to weld additional supports onto the back and put cinder blocks on them. 

For the seat, i cut apart an adjustable stool and welded on a bicycle seat post with saddle (saddle is the term for bicycle seat). And for the handle bars, a long pipe with the right diameter to accept a quill stem handle bar set.

And there it stood, finished at last. Or at least finished enough to work. I had in mind that once the deadline was met that i would come back and smooth out some of the rougher parts. For example, i never built a lid for it, just put a board on top. No time for lids. 

Another thing i would have liked to change was the way the straw was accessed. Either the whole kit and kaboodle had to be lifted off the top, or you had to bend down in and scoop it out. Neither was ideal. 

And to illustrate the process: 

The bucket on the left is the more finely chopped straw sifted from the coarser straw in the bucket on the right. The fine straw is ideal for doing finish earthen plasters- it has enough fiber to hold the clay together, but its small enough to disappear visually into the plaster. The coarser stuff, used for base coats of plaster, looks rough, and the individual pieces of straw are clearly visible from a distance. 

This is a close up of the finely chopped straw. Using the machine i built it took an hour of steady pedaling to produce one gallon of this ideal material. For comparison, 30-40 minutes of a weed whacker in a trash can (the current natural building standard) produces -i'm estimating- 15 to 20 gallons. Unfortunately, this disparity was too great for the pedal power straw chopper to be adopted into use by the natural building program. It was a let down, but i certainly couldn't argue with the conclusion. Regardless, it was a significant personal success- inventing and building a functioning machine from scratch with limited material and financial resources.

straw chopper 5

The next design challenge of the straw chopper became how to create a sturdy sealed container from which the blades could be removed without having to take the whole thing apart. Removable blades were necessary for two reasons, one, to be able to service the blades and, two, to be able to easily clean out the container. Coming up with some rough sketches of what that would look like was fairly easy. The design would be simple use, though, with limited resources, not necessarily simple to build.

If these drawings don't make sense- well, the first two are irrelevant (didn't end up building it that way)- then i'll explain a little what's going on. But not too much, cause you'll see how it works. My idea was that i build a frame for a rectangular container, the bottom of which would be semi-circular to account for the blades. Key to the removability of the blades would be two thick plates into which the blades could bolt. One plate is welded into the frame, and the other bolted. I'll explain more with the pictures.

I knew that there was a pretty thick piece of plate steel lying around somewhere, it would be perfect for making the two end plates for the container. I don't remember exactly, but i believe it was a quarter inch thick. Maybe 5/16".

To determine the size of the first plate, lets called it the fixed plate, i started by measuring the the diameter of the mower blades. I wanted the container to be relatively close to the blades, thinking it would help with cutting, but knew from my earlier tests that it couldn't be too close. I guessed an inch would be ideal clearance for that, and for other reasons i'll get to later.

So i drilled a small dimple into the plate metal, and utilizing my trusty make-shift compass, drew out 3/4 of a circle. I then drew a line along side the circle, touching the circle on only one point, then i drew a parallel line and cut out around what i'd drawn.






Then I grabbed another sheet of thinner metal, i think 1/8", and, after cleaning it up, drew and cut out the first piece of the removable plate.

For lack of a better word, the nipple on the removable plate is there to allow it to be bolted to the container. Eventually two more holes will get drilled in the top for more bolts.

I then drew and cut out two more pieces for the removable plate assembly.




The other nippled piece was similiarly cut out of the 1/8" metal, and the one with the smooth curve cut from the 1/4". Both of these pieces are only going to be thin arcs, their purpose is to extend the frame of the container downward in the exact dimensions of the removable plate.
 

 It took a lot of grinding to get them to the right size.

Next I found some small angle iron to make the frame of the container with. And, of course, it needed to be cleaned up.

Once the angle iron was free of rust, it was time to start welding. I was fortunate enough to have a speed square and a square to use for aligning the frame.



To get everything all lined up I used a trick that i learned from when i was building houses- you attach a connecting piece to one of your posts, in this case angle iron, and then get everything square and attach it to the second piece. (That's what that perpendicular piece to the left of the speed square is). I tack welded that in place (a tack weld is a small non-structural weld) and then tacked on another. Then i started playing with the removable plate assembly trying to figure out where it should go.







The picture below is of everything set in its final place, pre-welding. The first thing i welded on was that little perpendicular piece, it would serve as the backing for where the bolts would get welded onto the frame. 

Next i welded the smooth piece of the removable plate assembly to the frame.

 


I designed the frame so that as much of the welds would be hidden as possible. You can see why.



After welding on the first part of the removable plate assembly, i cut and prepared the second, nippled, piece to be welded on.


I wanted the second piece to lie flush with the frame so that the removable plate would fit without any gaps for the straw to get out. I happened to luck out that the angle iron and plate metal happened to be the same thickness. If they hadn't been i would have figured something else out, but fortunately it just worked.



Knowing that this weld was going to be exposed, i decided to hold off on it until i could get to a better welder. I tacked it in the meantime.



In the middle of working on the straw chopper i enrolled in a weekly night class- intro to welding. An overview, some of the science behind it, and an opportunity to bring in projects and work on them. And there it was, my opportunity to get the removable plate assembly welded all the way together.

The teacher was this guy. Dave Johnson. Nice fella.



It was pretty helpful to have someone who'd been welding for years to be able to give advice and constructive criticism. And though not beautiful, i was able make a much cleaner weld with a TIG welder than the stick welder* that belonged to Apro. *One of the constraints of a stick welder is that its meant for rough, thick metal- car chassis and things like that, getting a nice looking weld with stick is pretty tough, especially on thinner metal. TIG (Tungsten Inert Gas) makes a much finer weld, you have far more control over the heat and the precision of your weld. As far as i know its the most precise form there is. 

(I know this now, but didn't then) The orange discoloration all around the weld is from the tungsten electrode burning away. Too much heat for too long. The other give away is the color of the weld itself, a dull grey. Ideally the weld would be "light straw," slightly shiny with a subtle rainbow coloration like motor oil in a puddle. But i digress.

 

To complete the first side of the frame i needed to weld a brace along the top. I cut out a piece and set it on top to see what it would look like. The joint looked bad, clunky. I knew this thing wasn't going to be beautiful but this was an opportunity to put into practice some ideas i had about how to make welded joints look better.




I cut down the top brace so that it could lie flush in between the two vertical supports. I also angled the top so that the analogous pieces for the contiguous parts of the frame would all tie in together as flush and seamlessly as possible.




And again, welds on the back.

 

And there it stands, more or less together.




Next i cut out the excess material on the lower part of the frame to accommodate for the blade removal.




Then traced the removable plate onto the face of the lower frame, specifically so i could drill two holes where the bolts will go.



Again, to hide the ugliness of the welds, but moreover to ensure a flat surface for the removable plate to bolt to i welded the bolts from the backside.






When i put the plate on everything lined up well, except the very bottom hole. So i used a bit that i had purchased specifically for filing out holes (it doesn't get used with fingers though, it'll show up later in full form).

The next thing to figure out was how the blades would need to be prepared to have bolts put on them.




I cut off all the excess material around the axles, trying to give myself as much of a flat surface as possible.






Once I had the area around the axle all cut down i then started preparing the fixed plate to be able to accept the gear pictured next to it.

Using what i remembered from high school geometry i found the center point of where i wanted the gear to go. I then measured the diameter of the gear (adding a small increment in size to account for error), and transferred that measurement into my super high tech home made compass, drew the circle and began to drill.

I chose to drill out the hole, at least to get it started, because i didn't really have any other way of opening it up without having to cut all the way into it from the side, thereby ruining it.



When the center was all the way out, i then took a sawzall (a reciprocating saw) and cut out as much of it as i could without crossing the outer line.





Then i got out the ridiculously large drill- this thing probably weighed eight pounds- and filed out the hole with that special little bit. This was the part that i saw coming and bought the bit for. It made a huge difference.

 And voila! It fit great. 

I then prepared the frame for this side just as i did the last.



Next i drilled two holes in the fixed plate where the bolts from the end of the blades would pass through. Then i traced the holes that i drilled onto two pieces of metal that had been welded onto to the end of the blades. I drilled out the holes i traced and welded the bolts to the blades.



With that done i could then weld the fixed plate to the frame. Next i gave it the same top piece that the other side got and cut it loose from its temporary support pieces.





The next thing to do was to drill out all of the holes on the removable plate. Similar to the fixed plate, but more holes.



Once finished, it would look something like this.



With the plate ready i could now put brackets with bolts onto the blades. I got the blades into the vice and welded on four pieces of metal for the bolts.




I then used the plate to trace out where the bolt holes would get drilled. Drilled them. And then welded in the bolts.




With all of the bolts in place and the two sides pretty much finished, the hardest parts of the container were complete.