April 2019 – Welcome to Our Bear House!

My wife, Sara, likes to tap on things to the beat of the music… even if she can’t necessarily hear the rhythm. [Sara: Har har har. Very funny.] So in order to improve this from a habit to a skill, I decided to make her a cajon. Essentially, it’s a wood box that you both sit on and play as a percussion instrument. It has recently become more popular today, but originally was (and is) very widely used in Peruvian music. My knowledge of the instrument was limited and mostly derived from Mr. Ramsey’s Woodworking for Mere Mortals design.

These are some sample cajons:

To understand how to actually make this instrument, I needed to know the main components and how they work together. I broke down the project into three main components:

The box
The side of the box you hit (tapa)
The snare

The Box

My box was made of ¾-inch Baltic Birch plywood measuring approximately 12” X 12” X 18” tall. The top and bottom pieces have ¾-inch dados/rabbets along three sides. The top and bottom pieces are identical and measure 12” x 12”. The two side pieces have a single ¾-inch dado/rabbet running along its length and measure 12” x 18”.

The back panel is a single piece of ¾-inch plywood cut to fit. There was no need to cut dados or rabbets on this panel.

Before assembling the box, I considered the location of the sound hole and holes necessary to mount the snare. The sound hole is simply a hole in the back panel (the panel with no rabbet/dados), so I decided to put my hole toward the bottom center of the panel for aesthetic purposes. A hole was drilled in each of the side panels to allow a 1 ½-inch dowel to pass through (this is where the snare would be attached). It’s easiest if these sides are lined up, clamped together, and drilled at the same time to guarantee the holes are in the same place.

The Tapa

The tapa was made of a thinner plywood than the sides. I had some extra thin plywood lying around the shop that was slightly less than ¼-inch thick, so I decided to use that for the tapa side.

Assembly of the box was simple–just clamp and glue the five ¾-inch plywood sides together. The tapa was then cut to the exact dimension of the missing side of the box. The tapa is eventually screwed on the front opening, but access to the inside still necessary to install the snare assembly.

The Snare

The snare is a series of stiff wires that rest against a surface to produce a sharp rattling sound when the surface is struck and give the cajon the “drum” sound. From the inside of the cajon, the snare presses against the tapa (the side of the instrument you hit) to create that rattling sound typical in drums. The snare is mounted on a 1 ½-inch diameter wooden dowel that has the ability to turn, which allows the user to adjust the amount of snare sound heard during drumming–whether you want no snare for a more “wild” tone or more snare for more “drum” sound.

I purchased this snare from Amazon for the project. The length of the snare was adjusted by cutting it to a length of 5 inches with wire clippers. The goal was to get the snare to engage and disengage the tapa by the turning the wooden dowel.

Snare Assembly

For the permanently fixed knob, I glued the walnut knob securely to the end of the dowel rod. To make sure the knob was adequately glued in place, I also drilled a 1 ½-inch diameter recess to accept the end of the dowel. This allowed for a little more glue surface area and a more solid end cap.

To create the snare assembly, I created two knobs out of walnut for the exterior ends of the dowel rod. One knob would permanently be affixed to one dowel end, while the other would loosen and tighten the dowel within the box.

For the adjustable knob, I tapped ¼-inch-20 threads into the end grain of the rod to accept a 1/4 inch-20 threaded bolt. I used a ¼ inch-20 bolt and cut it to a length that would allow the knob to tighten the dowel assembly. The bolt was then epoxied into a small recess in the knob.

Final Assembly

The rod was fitted into the box and then the snare was screwed into place. Once I had the snare turning to my satisfaction, I moved on to the tapa.

View of the epoxied bolt into the knob hole before being screwed into the dowel. Casey had to make her mark (of course.. hehe).

Although the snare may look strange sticking out of the cajon, when it is pressed against the face of the tapa, it will create that “drum” sound.

The tapa just needed some recessed screw holes to attach it to the box for a cleaner look. I used some small screws to secure it in place onto the box.

Recessed holes for the screws to sit flat.

Here you can see that when the knob is turned, the snare will either be touching the face of the drum, or if turned more, will not be touching any part of the drum. This will change the tone of the drum from a more tribal sound to a more typical drum sound.

After everything was completed, the box was still looking a bit plain, so I added some walnut inlay around the sides and sound hole for decoration.

The end product was an attractive cajon that sounds pretty good!

Aerial photo of the walnut inlay and one of the knobs

Back view of the finished product branded at the top

My wife approves.

— Tim

Every year, Jet Propulsion Laboratory, or JPL, has an open house to the public to tour some parts of the campus and check out the latest things that they have been working on for NASA. JPL is part of the Caltech campus where they do a lot of outer space research and create lots of the technology that NASA uses for their expeditions.

We went to one of the public open houses a couple years ago, and it was really cool! The event is completely free, all you have to do is get tickets. But THIS year, we were able to go during the JPL Family Day to check out the new projects that they have been working on. JPL is very open about the technology that they are working on and don’t have too many classified projects, mostly because they want people to be excited about space and space technology and be engaged with what they are doing!

Walking in from the PARKING LOT!! (Hehe)

Mission Control

Mission Control is the room where all the outer space magic happens! It is where all the satellites are sending information, it’s running 24 hours a day, and is where all the space flights are controlled from.

From the JPL Deep Space Network website:

“The Deep Space Network – or DSN – is NASA’s international array of giant radio antennas that supports interplanetary spacecraft missions, plus a few that orbit Earth. The DSN also provides radar and radio astronomy observations that improve our understanding of the solar system and the larger universe.”

There are three facilities equal distances apart–one in Goldstone, CA, one in Madrid, Spain, and one in Canberra, Australia. These facilities collect information transmitted by satellites that we have sent to space and then send all that information to one place.. Mission Control!!

In the top left, the gray (they look blue) satellites and the green satellite reflect the transmission of information to and from Mission Control. They switch colors as they constantly send and collect information.

In the center of Mission Control, there is a plaque on the ground under plexiglass that says, “The Center of the Universe.” Ha! That’s because all of the information from SPACE is sent all the way to this very room. Science!!

I accidentally cut off the bottom part that says, “Universe”.. hehe.

Sibling shot after checking out Mission Control! (a bit blurry)

The Pulse

The Pulse is a really cool sculpture that they describe as the “heartbeat of deep space exploration.” This structure represents the “live communications of 30+ interplanetary spacecraft and the Deep Space Network.” Basically, the lights make really cool patterns, but when they are moving upward they are uplinking to space, and when they are moving downward, they are downlinking to Earth.

Mars Rover

Last time we came, we were able to see a life-size replica of the Mars Rover driving over a bunch of children laying on the ground (hehe). This time, the replica was located near Mission Control for everyone to check out.

Another thing we got to see is the Mars Yard! Basically, it is a small yard that the engineers created to test all the different rovers and wheels with different types of terrain and rocks to drive over to mimic what it would be like to drive on Mars. It was really interesting listening to the engineers describe how they try to anticipate different things they could run into, but it’s amazing to think of all the backup plans they have for actually running into these situations.

But nothing is certain when it comes to space, which I think gave me an even greater appreciation for what they do, since it’s pretty shocking to me that they can fly something MILLIONS of miles away AND successfully land it on a foreign planet AND then drive around AND STILL transmit information back to Earth. Amazing!

Mars 2020 Spacecraft

In another one of the buildings, they had a huge room where they are building the spacecraft for the next expedition to Mars! It was a really brief visit (they make you keep walking the whole time and you don’t have a great chance of taking pictures since everyone wants to see this).

What’s REALLY interesting to me (from experience working in many sterile settings in the hospital) is that all of the spacecraft that head into the great unknown to land on another planet are STERILE. Whoa! That’s because they don’t want to send any weird bacteria or organic Earth material to another planet when they don’t really know what the craft is going to encounter. Talk about foresight!

It’s the center spacecraft that is going on the 2020 expedition.

Pie ‘n Burger

After our morning trekking around the JPL campus, we had worked up an appetite and ended up going to lunch at Pie ‘n Burger, a place recommended to us by some of our friends. Parking wasn’t too bad–it was all street parking within a 2-minute walk.

This place had a very classic diner feel (but not quite classic diner prices… hehe). There was no wait for us around 1 PM on Sunday afternoon, but as we were there, the line started to get a little bit long.

Everyone was so hungry that I barely got any pictures in before they all dug in. Not even pictures of the pieces of pie!! The veggie burger was apparently DELICIOUS (per Casey and Tim), as was the grilled cheese. Tristan and I got the patty melt, which was pretty tasty as far as patty melts go. Ben and Jane got the chili cheese fries (the Hat seems to give you a much bigger portion) and a chicken pot pie that had a crust so flaky you could feel the butter settling into your arteries.

Patty melt on sourdough bread. The cheese was so soft and melty inside..

Another thing to note is that this place is cash or check only. Who uses checks to pay for food anymore? There is an ATM located right at the front if you need cash though. And they have this cool vintage cash register that they have probably been using since they opened.

Pie ‘n Burger was pretty good, but I’m not sure if we need to go back right away. I enjoyed the food a lot, but I kind of thought the pie would be more mind-blowing, especially if it’s a place with “pie” in the name. Either way though, it was a perfect way to end our JPL day!

Month: April 2019

DIY Cajon Drum