How to drive a steam locomotive

I recently got to drive a steam locomotive! The Nevada Northern Railway in Ely, NV, allows you to Be the Engineer for a 14-mile trip up and down hills, through two tunnels, and across several road crossings. This is an incredible experience – visually and physically!

(By the way – I learned that you “run” or “operate” an engine, not “drive” it, since no steering is involved. But that is how they describe the experience to newcomers :) )

Did you ever see such a beautiful engine?

NN 40, built by Baldwin in 1910

Before climbing into the engineer’s seat, I had to study a 122-page rulebook and take a short (open book) exam. I learned about whistle signals, hand signals, speed limits, track warrants, air brakes, and more. I learned radio protocol (interestingly, it’s backwards from typical airplane conventions; you announce who you are and then who you want to speak with, e.g., “NN 93 to NN Conductor 93, over”). In addition, “the use of ten codes” (I assume this means things like “10-4”) is prohibited.

I also helped get the engine ready for action. The rest of the crew gave me small jobs, like greasing the many bolts that connect rods and other pieces, and refilling the oil reservoirs. Meanwhile, they stoked up the fire in the boiler, cleaned the engine, filled up the tender’s 6000-gallon water tank, and ensured we had enough coal. The steam engine goes through 75 gallons of water *per mile* and consumes about a ton of coal in the 14-mile trip we did!

After three hours of prep, the engine was ready to go! I climbed up into the cab and learned how to start and stop the engine, then practiced this while we were still in the railyard.

The primary controls are the throttle and the brake. The throttle is a squeeze lever with many (~20) detents. Bouncing along, it requires some fine eye-hand coordination to move it precisely to the desired notch. It, too, is backwards from the throttle on an airplane: moving it out (towards you) gives you more steam, not less!

The brake is a smaller handle, easier to manipulate. If you want to slow down, you move it to a setting that allows compressed air into the brake cylinders, pressing the brake shoes against the wheels. You monitor how much brake you are applying through a pressure gauge. Then you move the handle the other direction to release the compressed air (you can hear it hiss out) and the wheels resume unimpeded motion.

The massive locomotive responds slowly to control changes, so both controls are best applied with careful anticipation of the upcoming track – its grade, any curves, preparation for tunnels, etc.

There is also a reversing lever that is mounted vertically in the floor. As one of my books warns, “A strong arm is needed for the reversing lever!” It has a more subtle effect on locomotion by altering the amount of steam that gets into the piston cylinders on each stroke. You want it set full forward to get moving, then back it off for “cruise” to achieve more efficient operations.

And we were off! We left the railyard and climbed a gentle hill. We went through two tunnels and several road crossings. For each crossing, I blew the whistle – LONG LONG short LONG! Mike, our fireman, was busy shoveling coal as needed, injecting more water into the boiler, and ringing the bell through all crossings as well. What a delightful noise!

We used a GPS-based speedometer to track our speed, which stopped working each time we went into a tunnel. However, after a while you get a feel for speed based on the sound of the pistons (and such a lovely sound it is). Pistons mounted on each side provide the driving power for the large wheels. Each wheel gets driven twice per rotation (unlike engines in cars, airplanes, etc.):

In addition, the left and right wheels are offset in phase so that one side gets maximal torque when the other is at minimum (end of its stroke). So what you hear is CHUFF-chuff-chuff-chuff as the pistons go right-forward, left-forward, right-back, left-back, for a smooth continuous overall motion.

At the top of the hill, I gave the controls over to John, the engineer who was training me, and he traced our way through a “wye” (track set up to enable a three-point turn by an engine), which got us set up to return back downhill.

We then continued back down the hill to return to the railyard. The whole trip took about an hour and 15 minutes. After the initial learning curve, it got very comfortable to roll along and listen and respond to the chuff of the pistons as needed. My mind quieted and I filled up with the pure joy of the moment. What an overwhelming experience!

Me driving Number 40

Thank you to Richard Ondrovic for taking these fantastic photos!

The Tool Petting Zoo

Yesterday I volunteered with Kids Building Things to offer a Tool Petting Zoo. This is a chance for kids (and their parents) to see, touch, and use tools of all kinds — screwdrivers, bubble level, wire cutters, hammers, saw, a drill press, and more.

Even better, I got to learn some new tools myself! I got to use a pipe cutter, which looks like this:

You put the pipe inside its jaws and then spin the screw until it grips the pipe. Then you rotate the cutter around the pipe, tightening the screw whenever it feels slack, until it slices through the pipe. Magic!

I then got to use a pipe bender:

This picture shows a pipe after it’s been bent with the tool. It requires very little effort. You put the flat pipe through the device. Then, as you squeeze the handles together, the pipe bends in a nice curve, supported by the metal disk, which dictates the radius of curvature. You stop squeezing when you have as much curve as you want. This is great fun!

Finally, I learned to use a rivet puller:

You line up the holes in whatever pieces you want to attach, then put a rivet through it and squeeze the handle. This pulls the bottom of the rivet up, fattening it out on the reverse side, and eventually it can pull no further, the top snaps off, and you’re left with a beautiful rivet.

The kids were encouraged to make a sculpture, or whatever they wanted, with the tools. I made a mini Loch Ness monster:


Check out my cool rivets and bent pipe!

Cardboard automata

Cardboard automata are machines made out of cardboard. They are often operated by a hand crank or dial to initiate the motion. As the primary axle turns, cams attached to it cause cam followers to rise, fall, or spin, depending on their geometry.

Just based on that description, who could resist diving in immediately to make one?

Not me.

Plus, I had an assignment from my Maker Space class to “make something you’ve never made before.” Bingo!

I discovered an excellent set of instructions, with pictures, created by The PIE (Play – Invent – Explore) Institute. I decided it would be a fun challenge to make as much of the project as possible out of “found” (available) items in my home.

box-cornersI cut a cardboard box in half, then reinforced the corners to prevent it from collapsing sideways. I cut a hole in each side of the box to connect an axle across it. The instructions suggested using skewers for the axle and cam shafts, but since I didn’t have any, I instead used some wooden dowels I had lying around. I thought they might create a more sturdy result. However, I didn’t have a dowel long enough to span the box, so I temporarily taped three dowels together to build my first prototype. I cut out some cams out of craft foam and slid them onto the axle at different positions.

cam-followersI also created three cam followers by cutting circles out of the foam and inserting more dowels into their centers. Then I cut three holes in the top of the box for the cam followers and connected everything together.

I chose three different cam designs for my three units. The middle cam is round and centered, which generates rotation in the cam follower. The left cam is egg-shaped, which generates rotation and vertical motion. The two right cams are round but off center, and they are positioned to be 180 degrees out of phase. Therefore, they alternate in their contact with the cam follower, which goes up and down and alternates between clockwise and counter-clockwise rotation.

tubesAt this point, when I turned the axle, the dowels wiggled back and forth and sometimes moved themselves off their cams. I consulted the instructions, which advised inserting drinking straws into the top holes so the skewers have a strong guide to keep them aligned. My dowels were far too thick for straws, so I cut up a cereal box to get a firm yet shapeable cardboard sheet. I rolled this cardboard to create tubes that were just slightly larger than the cam shaft dowels. The machine’s performance improved dramatically, and I decided it was time to glue everything down: the tubes in their holes, the cam followers to their shafts, and the cams to the axle. And it worked!

Once I had a working machine, I was free to add whatever design elements I wanted. Extending the cardboard design theme, I found instructions for how to make flowers from toilet paper rolls as well as a sprout/palm-like plant for the middle cam shaft. I glued green paper and brown felt onto the top to give it a nature-inspired look, added some paper flowers, and cut out a paper backdrop of twisting grass shapes to accentuate the feeling of motion. Finally, I used colored markers to decorate the cam followers so that their motion (and its direction) is more visually evident, since the mechanism is a focal point of the project.

Here is a longer video that explains the parts of the machine.

My first day roving on Mars

I recently joined the Mars Exploration Rover team as a TAP/SIE (Tactical Activity Planner / Sequence Integration Engineer) for the Opportunity rover. That means it’s my job to sit in on the morning SOWG (Science Operations Working Group) meeting, in which the rover’s scientific goals for the day are set, and then work with payload, thermal, downlink, mobility, and other experts to come up with a plan to achieve those goals. What pictures will we take? When? Where will we drive? Is there enough power?

Reading the training documents only gets you so far. I’ve just begun “shadowing” the current TAP/SIEs so that I can learn on the job, watching over their shoulders through a day of planning. My first shift was on Wednesday, and it was supposed to be an “easy” day: pick one of two rock targets, drive towards it, and take some pictures looking backward at yesterday’s tracks.

Scientists dialed in from all over the country for the SOWG meeting. After some debate and consultation with the Rover Planners, they settled on the rock that had the easiest approach. The scientists signed off and we went to work building the plan.

The TAP/SIE’s job is facilitated by a bewildering array of scripts and tools. These allow for the setup, development, refinement, and checking of the plan. Are power or thermal constraints violated? Do we have enough onboard storage space for the new images to be collected and enough downlink allocation to get them back to Earth?

While the RPs (Rover Planners) settled in to their job of constructing the drive sequence, we worked on the full sol’s plan (a day on Mars, which is 24 hours and 40 minutes in Earth time, is called a sol). Very quickly we realized that the planned drive, despite covering only a couple of meters, would drain the rover’s battery dangerously low. Opportunity was starting the sol at only 80% charge because of two long instrument observations the previous sol.

We modified the plan to give the rover a morning “nap” in which it could sun itself and collect power, like a desert lizard. That helped the power situation, but not enough. Several iterations later, we finally squeaked by at 0.1 Amp-hour above the required threshold.

Meanwhile, the RPs were growing concerned about a different problem. To reach its goal, Opportunity would have to straddle a rock that, while small by human standards, could pose a risk to the rover’s instrument arm, which dangles slightly down when stowed for driving. The RPs put their 3D simulation of the rover and the terrain up for all to see, and we stared at the screen while they spun the rover and tried to examine the rock from all angles.

“Can we raise the arm while it drives over the rock?” I whispered to the TAP/SIE I was shadowing. “It’s risky to do that,” she whispered back. “The arm bobs around, especially going over a big rock.”

A few minutes later, a scientist on the telecon asked, “Can’t we just put the arm up?” but was quickly shot down by the TUL (Tactical Uplink Lead, head planner): “Too risky.” The TAP/SIE and I grinned at each other.

Ultimately, it was deemed too dangeous to drive over the rock with our current data (images the rover had taken the sol before), and they decided to drive up to that rock and stop. Post-drive imaging would illuminate the obstacle in more detail.

At the end of our shift, which apparently was two hours later than usual, we had a plan. We ran it through multiple checks and re-checks and manually confirmed all of the sequences. The final walk-through was punctuated with “check!” coming from different areas of the room as each person confirmed that their part was correctly represented. The plan was finalized and transmitted to the rover using the Deep Space Network later that night.

There’s nothing like seeing a job in action. I learned a lot about the steps involved in planning and (unexpectedly) a lot of re-planning. For the rover, today is “tosol” and yesterday is “yestersol.” I got to practice the phonetic alphabet, which is used to communicate letters (in rover sequence ids) with a minimal chance that they will be misheard. I even got to help out a bit as a second pair of eyes to catch typos, spot constraint violations, and suggest alternative solutions. And I’ll be back on shift next Monday!

Opportunity is near Endeavor Crater, working its way along a ridge that is at the perfect tilt to keep its solar arrays pointed toward the sun. This is important because Winter Is Coming, even on Mars, and we want to keep it sufficiently powered to make it through to spring — its fifth spring on Mars. (Opportunity landed 9.5 Earth years ago!)

Radiant barrier plywood works!

When the contractor tore off my old shingles to replace my roof, they found that underneath were the original wooden shingles. California code no longer permits wooden shingles (fire hazard!), so these had to come off, too. But the wooden shingles were laid on slats with 6-inch gaps between them, so that meant I also needed a layer of plywood put down to support the new shingles. California code (at least in my town) also requires that this plywood be radiant barrier plywood, which is plywood with a foil backing on one side. You lay the plywood shiny-side *down*, and then in theory it reflects heat back up through the shingles, reducing what gets into the attic.

My contractor was skeptical as to whether this plywood would really make a difference, but agreed to install it per code. (It is also not much more expensive than regular plywood.) Naturally, I wanted to test it empirically. So I collected some data.

My SCE smart meter reports the maximum daily temperature and my energy consumption per hour online. I have my thermostat set to 85 F during the day, and I can track when the air conditioner came on by looking for a spike in energy consumption. I defined the hour at which the A/C came on (i.e., internal house temperature reached 85 F) as an hourly consumption greater than 1 kWh. In the following plot, I show the time when the A/C came on as a function of maximum outside temperature. Higher values are better (later in the day). And sure enough, the new roof out-performs the old one.

Note that I used a linear fit here, but that probably isn’t appropriate at higher temperatures. Also, the times are capped at 18:00 (6 p.m.) as that’s when my thermostat switches to “evening” mode and tries to drive the temperature down to 82 F instead of 85 F.

Caveats: this is the result of the roof as a package, not just the plywood. I also had attic vents installed that probably help keep the attic cooler. It’s also possible that I’m seeing more of an effect than others might, because as far as I can tell my house has no insulation in the ceiling (California!). Thus, the living space and attic are more coupled than they would be with insulation.

Overall, however, I’m pleased to see that my new roof is performing so well! The only down side of the radiant barrier plywood is that it came with an intense chemical smell that soaked down through the attic into the living space and, on hot days, was so bad that I had to turn off the A/C so I could open the windows and tough out the heat just to be able to breathe. I couldn’t access the attic at all. Happily, after about three weeks, this finally faded away. The manufacturer claims this is due to the glue in the plywood.

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