The Garbage Man Can

Baltimore has a bit of a floating debris problem. This outflow channel comes down from the city into the harbor and when the tide is flowing out, the channel is helping thousands and thousands of pieces of trash float down into the open waters.

Luckily, the issue is not without checks. This floating barrier collects a large portion of the trash before it is able to make it out into the harbor. Then, who comes to the rescue but the garbage man, piloting the garbage boat!

I have seen many different garbage trucks in my life, and a few more interesting machines to collect trash like street sweepers and leaf vacuum trucks, but this was by far the most sophisticated garbage collecting boat I’ve ever seen!

Front gates that raise and lower work in concert with two conveyor belts in series, and a all of this is mounted to a nimble sea craft. See how it works in the video below:

As you may notice from the video, some of the trash does get away. The very actions by which the boat collects most of the trash actually disturb the floating barrier and allow some trash to float past. Still, the combined solution of the floating barrier and garbage boat do prevent a lot of aquatic pollution.

Harmonic Beauty

Do you know what a pendulum wave is? A few months ago, I didn’t either. But one day someone showed me a video of it online and I suddenly realized that I had to build one.

A pendulum wave is a series of pendulums hung in a line, each with a slightly different length (from attachment point to bob) according to a specific ratio. For example, if your first pendulum hangs 10cm below it’s attachment point, the next might hang 15/16ths of that height (or 9.375cm), the next would be 14/16th of the 10cm height, the next 13/16, etc. Each subsequent pendulum length relating back to the first length. Using a spreadsheet, it’s easy enough to calculate these ratios for any set of lengths.

Because the length of a pendulum determines its period (how long it takes to oscillate from one side to the other and back), each pendulum in our line has a slightly different period. And because you created the lengths precisely according to this ratio, the periods also have a precise relationship.

When you create a series of these pendulums, you create some amazingly cool patterns. The pendulums will cycle in and out of sync repeatedly until friction slows them down to a stop. Or, if you use a computer to program them, you can have it loop endlessly. Here I’ve included a short clip showing one cycle of twelve pendulums moving out of sync and back It takes a minute, but this is at 1/4th speed. This program was written and recorded from Processing software, available free online. Email me if you’d like the source code.

Once I had this working in a digital model, it was time to get physical. I decided to laser cut the stand for the pendulums, to take as much of the guess work as possible out of the heights. Of course, there was still some error due to inaccuracy in hanging each bob, which is why in this physical model, the pendulums do not come back into sync perfectly. This video is shown at 1/8th speed.

Finally, I also included blue LEDs in each pendulum, to highlight the motion. The suspension wires for each bob did double-duty as the leads for the LED power.



In the next version of this project I will definitely use something like guitar tuning screws to allow for precise tuning of each pendulum. This was a fun initial foray into building a sculpture which gets its beauty from highlighting a natural phenomenon.

Simple. Simpler. Simplest Machines.

The term simple machines should really be “simplest machines.” A can opener should count as a simple machine, but if pulleys, wheels, and levers are in that category, then a can opener certainly can’t be.

During the course of the last six months, I’ve had to buy three new can openers. Increasing in price from left to right, these three each graced my kitchen utensil drawer at one point. The third and final opener works well and consistently every time. Thanks OXO. The other two failed to even open the very first can. They had not worn down over time, they were just not designed well for the job. No thanks, Target.

What’s a can opener that doesn’t open cans?

Well, the good news is that they products are at least interesting shapes to look at. The non-functional openers are now pleasant citizens of my “cool things to look at and play with” shelf!

Bottom Line? Printers Cover Their Backs

Printers are amazing machines. Even the simplest printers today have hundreds of parts and are capable of stunning print position accuracy. So much design, engineering and forethought goes into these machines which can cost less than $100 and are cheaper to replace than to repair.

Printers also happen to be fascinating to tear apart!

In a humble desktop ink jet color printer I found four motors, a huge number of gears and switches, connectors, electronics and all sorts of other cool components. Next time you are getting ready to throw away a printer, let me suggest grabbing a screw driver and pulling it apart first. It’s a fascinating way to spend an hour or two and a very fun activity to do with kids (just make sure to be safe about the electrical parts!).

In this latest tear down, I was intrigued to find an extremely absorbent pad at the bottom of the printer, just below the ink storage. As you can see, in this printer over half of that pad was thoroughly soaked with ink.

The presence of this pad in the first place means that despite all the engineering and design, the printers were still expected to produce a significant amount of leakage over their lifetime. As you can see from how much it has been used, it was clearly a good choice.

Before this little tear down, I never knew that printers had this safety feature to cover my back.