Kid Engineer: Compost Tumbler | Design Squad


Hi! I’m Zuzu
from Design Squad Global and this is Kyra. We’re here
at the East Boston Y.M.C.A. to check out their garden. ZUZU: You got it? I got it out! My first one. ZUZU: The kids at the Y.M.C.A.
grow vegetables and make food in their kitchen. In cities, there isn’t a lot
of space, so they make the most
of their space by using one bed to grow
their vegetables. Their garden needs healthy soil
to help the plants grow. Right now, they have to buy
compost, which is a mixture
of vegetable and organic waste, to fertilize the soil. The kids at the Y.M.C.A.
told us it’d be great to have
a compost tumbler so that they can make
their own compost. A composter is made
of simple machines that make it easier
to spin the compost so it gets easily mixed. Mixing helps food scraps
like fruits and vegetables turn into compost
to help feed the soil. We’re at Parts and Crafts,
a maker space for kids. This is Dave. He’s a carpenter and builder, and he’s going to help us build
our compost tumbler. We’re using a recycled
rain barrel for our compost tumbler. This should hold enough compost
for the garden at the Y.M.C.A. First, we brainstormed ideas
and sketched our designs. We were talking
about having something stick out from the barrel. So the axle would be coming out
of it. The frame would be here
and supporting that. ZUZU: Our design uses
two X-frames to support an axle that runs through the center
of the barrel. This allows the compost tumbler
to spin and mix the compost. KYRA: This is 35. ZUZU: 35 it is. We measured all the parts
of our design so that we could start building. We’re making our frame
out of two-by-fours. (saw buzzing) Our frame is two Xs
linked by two braces. We’re using PVC pipe
for our axle. Our axle will run
through the center of the barrel and rest on our frame. (saw buzzing) Now we need to find
the exact center of the end of the barrel so that we drill our axle holes
in the right spot. First, we found the center
of the Y axis, and then we draw our X axis line and we found the center
of the X axis. That’ll give us the center
for the barrel where we can drill the hole
for the axle. DAVE: Good job. ZUZU: We’re installing a hatch so that we can access
the compost. We’re designing a hatch
that’s big enough for a shovel and that’s easy to reach. DAVE: So not up here. KYRA (laughs): No.
DAVE: Okay. (laughs) ZUZU: We use nuts and bolts
to attach the hinges. The hinges allow us
to open and close the latch to access the compost. Compost has lots of organisms,
like bacteria and small animals, that help turn the vegetables
and plant scraps into compost. These organisms breath oxygen,
so the compost needs air to help it decompose. We’re drilling holes in the side
of the barrel to add air to the compost. The reason
that a compost tumbler tumbles is to mix in air
to speed up the process of breaking down the waste. All right, so now we need
to come up with something that will mix the compost. KYRA: Yeah, if we have fins
varying in different places, it will agitate the compost
more. ZUZU: Kind of like
a washing machine. We’re making
our compost-mixing fins out of PVC pipes
that we’ve cut in half. Okay, cool. We’re varying
the size and spacing of our fins inside the tumbler so the compost will be
thoroughly mixed when the kids at the Y.M.C.A.
turn it. I like your guys’ placement–
good job. So this is a 55-gallon drum, and when this is filled
with dirt, this thing is going to be
pretty heavy. KYRA: We added a crank handle
to the barrel so it’s easier to turn
when it’s full of compost. The handle acts as a lever, rotating around a center point
called a fulcrum. By using a lever,
we multiply the force we’re able to apply
to turning the barrel. (laughs) Oh, that’s so fun. ZUZU:
We added furniture legs to make it look
like a pirate ship wheel. DAVE: Beautiful. That’s a cool
compost tumbler. ZUZU: Now it’s time to show
the kids at the Y.M.C.A. their new compost tumbler. BOY: That’s cool. ZUZU: Now the kids
at the Y.M.C.A. can use their new
compost tumbler to convert their food scraps
and garden scraps into compost for their soil, so they can grow
lots more vegetables in their garden. Do you have an idea for a device
that can help out in the garden? Send us your ideas to
the Design Squad Global website. Design Squad Global!

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