Woodworking – Welcome to Our Bear House!

April 29, 2019April 29, 2019

DIY Cajon Drum

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

November 13, 2018

Simple Cutting Board

I picked up some 4/4 rough cumaru (aka Brazilian teak) on sale at my local hardwood lumberyard a couple years ago and I finally found a fun use for it. I made a series of simple cutting boards for family and friends. This little project is all about bringing out the beauty of rough lumber.

First, I cut the lumber to its approximate final dimensions using my miter saw and table saw. This cutting board ended up being about 10 inches by 14 inches.

The project’s width was limited to 10” due to my jointer’s capacity. I own an INCA 510 combination jointer/planer. These days, you can only find these machines in used condition because the company, INCA, no longer exists. This tool was likely built in Switzerland in the 1980s.

INCA 510 (343.190.01) with single phase Dayton 1-1/2 hp motor

1980’s INCA equipped with the original mobile table

10-1/4 inch jointer and planer capacity. Check out that nifty articulating blade guard.

The 10 ¼ inch capacity on the jointer is one of my favorite features of this tool. After passing one side over the jointer to check flatness, I placed the board jointed side down on my table saw cast iron to see if it sat perfectly flat. If I detected any sort of wobble, I sent it back to the jointer for another pass. Once I established flatness on one side, I placed the flat side down on the planer bed to plane the other side. I sent it through several times taking care not to overload my INCA. The end result is a ¾ inch thick board that has equal thickness throughout.

To take all the sharp edges off, I gave the cutting board a 1/8 inch round-over on my router table.

Temporary shop built router table with 1/8 inch round-over bit

I sanded the cumaru first with 150 then with 220. There were minor imperfections with the edge routing that were easily sanded out. My planer leaves minimal snipe, so I’m comfortable cutting the work piece to final dimensions before planning. If there is snipe present, it’s nearly invisible and easily sanded out.

DeWalt DWE6421 random orbital sander and down-draft table setup.

Finally, I branded the cutting board with my custom branding iron and applied some butcher-block oil.

Another shot of the cumaru cutting board

This is hardwood is extremely dense and heavy. Part of the reason I love this wood is that the board sits stationary on the countertop during chopping even though has no “feet.” I originally had concerns with silica content of this hardwood, making it a poorer choice for a cutting board due to knife dulling, but after some trial by family and friends, we found that the character of the wood has little to no dulling effect.

Cheers!

-Tim

September 18, 2018September 18, 2018

Pair of Studio Tables

Our church was considering purchasing two tables for their new filming studio, but there was not really an affordable option that fit the dimension requirements that we needed. I volunteered my woodshop for the project and designed two tables that would fit the bill. A few requirements I had to consider when designing were:

66” long x 18” wide x 30” tall
Table apron/overhang that extended past the knee on the side facing the camera to not distract from the film subject
Weight is light enough for a single person to move easily

I wanted to work with a hardwood for the legs and rails, but I knew a solid hardwood top would be too heavy, so I figured I could create a grid structure out of pine and then laminate ¼” sheets of plywood to either side. Then I could trim the top with hardwood to conceal any unsightly plywood and pine that was showing. This top would be strong and light, but the idea of a cheap plywood top paired with a beautiful hardwood base would look a little mismatched. After a lot of consideration on the type of material I would use for the top, I settled on painting the plywood portion of the top black. The apron would also be painted black to match.

I purchased 37 board feet (BF) of 6/4 Cherry for the legs, rails, and trim. The hardwood store’s selection of wood suitable for the legs was unsatisfactory—mostly on account of its price ($4.66/BF for 6/4 Cherry vs. $25.00/BF for Cherry leg blanks). It was more cost effective to laminate the 6/4 Cherry for the legs.

37 board feet of cherry wood

The hardwood sat in my garage for a couple months before I actually got around to the project.

Charlie giving moral support

I milled all the lumber required for the legs first. Once all the legs were laminated, they were cut to final length.

Milled legs

A taper was applied to the inside leg faces with my table saw using a custom shop-made jig.

Base joinery was mortise in tenon. I cut a dado in the legs and rails that would accept the panels forming the apron. The mortises were cut on my makeshift router table using a ¼” straight bit and the dados were cut on the table saw using a single blade from my dado stack. I squared and cleaned up the mortises with a 1/2” chisel. Tenons were cut on table saw using a shop made jig. Fortunately, the height of the garage allowed me to cut the rails vertically on the table saw using the jig.

Dados in legs and rail pieces

A dry fit of all the components was done to plan for a successful glue up.

The grid for the top was formed with some pine purchased from the local Home Depot, and I milled the pine down to ensure it would form a perfectly flat grid once assembled. Pocket holes were used to create the grid skeleton.

Pine grid for table top

The frame was lightly sanded before laminating the ¼” plywood to the top.

Light sanding of top with laminated plywood

The tops and aprons were painted black using General Finishes Lamp Black milk paint.

The rails and legs were sanded with 150 grit and then 220 grit. All the edges got an 1/8” round over on the router table.

I prefinished all the components with three coats of General Finishes Arm-R-Seal, and I was careful not to apply finish to the mortises or tenons, as these glue surfaces would be ineffective if covered with Arm-R-Seal.

After 3rd coat of prefinish on legs and rails

I glued the base together carefully to get the orientation of each piece exactly right. Pocket holes had been predrilled prior to finishing and assembly, and these holes were used to fasten the top to the base.

Base glue-up with aprons

The final step was to create the mitered trim and finish the top. I didn’t have the right size stock left over for the cherry trim so I had to pick up an extra board to finish the project, and ended up trimming the top to the right length at the miter saw. This eventually made the corners have really tight miters.

The top was finished with four coats of Arm-R-Seal and a final buffing.

The final product was a simply designed, very light yet durable table suitable for a film studio.