Dresser for Little “C”

Dresser / changing table for my youngest daughter’s new arrival. Top, sides, and drawer fronts made from red oak. Five foot long, 35 inches high, 21 inches deep.

I turned the feet out of 3-1/2 x 3-1/2 oak glue-ups. First I cut the tapers on the bandsaw, the waste was taped back in place to keep a stable surface while cutting the other three sides. Each foot was turned between centers on the lathe using a parting tool to mark the transitions and a small gouge to cut the concave curves. They were sanded while still mounted on the lathe.

Next I made the sides using a frame with a floating center panel. The center solid oak panel was made from a three board glue-up. Rabbets were cut on all four sides that fit in dados cut in the frame pieces. To allow for wood movement across the grain, I cut the head off a 2 inch finish nail and inserted it into holes drilled in the vertical frame members and the center of the panel. This keeps the panel centered within the frame. The edges of the panel were shaped to fit into the tapered grove in the frame sides to prevent weakening the mortise and tenons joining the frame pieces together.

The rear frame of the dresser consisted of two horizontal 6/4 pieces of popular attached with two mortises to each side panel. The front faces of the popular pieces had a 1/2 inch rabbet cut to allow a 1/2 plywood panel to be inset. The plywood panel squared up the frame and provided a structural surface to mount rails which supported the rear of the drawer slides described next.

Next job was to mount the drawer slides. I elected to use 100 pound capacity full extension slides. To support the rear ends of the slides, I cut notches in construction fir 2×4 sized to match the width of the vertical members in the front face frame. These were screwed to the rear plywood panel. On the front face of the rear supports I added yellow pine whose width matched the notches cut in the fir. These pieces provided a solid surface for the screws which secured the rear of the slides.
Additional oak pieces were attached to the rear faces of the vertical front face to provide a fastening surface for the front of the slides. They also overlapped the mortise and tenon joints for some added support.
Temporary blocks were used to locate the front end of slides when they were attached to the frame.

Drawers were made from 1/2 inch plywood sides and 3/4 inch plywood false fronts and rears. Dados to hold the drawer bottoms made from 3/16 hardboard were cut in the sides and front. The drawer rear was sized to set on top of the drawer bottom. The sides were fastened to the fronts and backs with a brad nailer after gluing. To increase the rigidity of the bottom on the larger drawers, a 1/4 inch deep notch to accomodate a 1-1/4 wide inch pine slat was cut in the center of the drawer false front. The slat was glued to the drawer bottom and a screw inserted into the 3/4 inch false drawer front and drawer rear.
A simple jig was made to accurately position the inner slide rail to the side of each drawer. Slide positions were determined to provide about a 1/4 inch of overhang of the solid oak true front above and below the false front. On the large drawer faces, a 1/8 inch wide x 3/16 inch deep groove was cut 1-1/4 inch in from all edges of the true drawer fronts. Fifty cent coins were used to space the true drawer fronts top/bottom and side to side within the drawer openings against the drawer’s false front face. The screw holes for the drawer pulls registered the true drawer front to the drawer. After gluing and clamping, two screws drilled inside the rear face of the false front secured the true fronts to the drawers.

The cabinet bottom panel was made from 3/16 hardboard sized to fit within the bottom of the dresser and to fit flush with the top of the bottom front frame members. Blocks attached to the inner surfaces of the front and rear frame supported the bottom at the flush height. Small counter-sunk screws held the bottom panel to the bottom blocks.
Corner blocks to hold the dresser feet were made to fit in the bottom corners. A forstner bit sized to accommodate a counter-sink bit was used to bore holes in the 45 degree face of the block. These holes secured the block to the sides. Screws counter bored through the front and back frame faces secured the blocks on its other face. 3/8 inch oak plugs were inserted over the screws on the front face. The feet were attached to the blocks with 1 number 10 screw in the center, and a shorter number 8 screw 3/4 inch to the side to keep the feet from rotating.

The 5 foot top was made from 3 edge jointed solid oak boards. To get a straight edge on the 4/4 rough sawn boards, I used the straight edge of a piece of mdf wider than the boards to ride against the fence after fastening the oak to the mdf with 2 screws located within 1/4 inch of the worst edge. After the first cut, I removed the mdf and used the newly created straight edge against the fence to true the other long side of the board. This provided edges which required no planing before edge gluing. I used 3/8 inch dowels in the two inner edges of the glue-up along with clamping cawls to get a very flat top.
To attach the top to the chest, a 6/4 piece of oak first had three holes drilled at each end. The two outer holes on each end were slotted to allow for wood movement. The block was then attached to the inside top end of the chest with two screws. The top was then centered on the chest and clamped in place. Then the three screws on each end were drilled and secured.

Raspberry Pi Doorbell

Status

Hello World! This is my first post on Stretch’s Saw Dust Sessions. I’m the “Zeek” in the title. Recently my father, Stretch, visited me at my home on the East Coast. We typically do a few improvement projects around the house (You can probably pick out a few out from my father’s catalog). I am a geek at heart so I like to dabble in programming / electronics / toys projects whenever my father visits. While we typically do wood projects, I like to try to sneak in a few of my own pet projects now and then.

Recently my doorbell had quit working at the house, which is surprising since it was built within the past 3 years and the doorbell didn’t even last 2. I had been browsing a few sites to replace my doorbell with something more… techy. I found some pretty interesting projects using Bluetooth implementations along with webcams. While those were pretty cool there were a few requirements I desired:

  1. I didn’t want the doorbell to use Bluetooth
  2. I didn’t want to have to drill any additional holes in the walls
  3. I didn’t want to run additional cables

After talking to my father, he suggested we could use the current wiring with a Raspberry Pi to detect a push of the doorbell. So, without any more rambling let’s get into how we did this.

Here is a list of things you need for this project:

  1. Raspberry Pi 3
  2. 8 GB microSD class 10 Memory for Raspberry Pi
  3. Step Down Power Supply
  4. USB Cord
  5. Speakers (USB or Mini-jack)
  6. Jumper Wires

If you want the source code for the test.py and doorbell.py, you can view it here.

The first step was to measure the voltage from the transformer that powered the old doorbell. In my garage, we found the doorbell transformer that ran to the front of the house. Using a multi-meter were found out that it was producing 24 Volts (a/c).

Doorbell transformer in the garage, feeding 24vac to the doorbell.

The transformer feed comes out near the front door. Another cable ran to the doorbell so that when the circuit is closed (by pressing the doorbell), it would complete the circuit that powered the ringer. This is where we would stage our setup.

Front door outlet from the transformer

A Raspberry Pi requires 5v dc input voltage to power the device. In order to step down the voltage, I needed to buy a step down rectifying power supply. Conveniently, Amazon has these in stock. The a/c input voltage connections are at the back left (if you’re looking down at the device) and the output connections on the front right. We used a multi-meter to determine which wires came from the transformer, and which ran to the door bell switch. We had 2 separate cables, with 2 wires in each.

After installing the Step Down power supply, we cut the USB cable to leave 8 inches of cable from the micro-USB connector – which will plug into the power connector on the Raspberry Pi. We stripped 1 inch of the micro-USB cable to check the wire coding and connections. I used this diagram to determine that we only needed the red and black wires for the micro-USB to power the Raspberry Pi. We clipped back the green and white wires on the micro-USB cable so that they wouldn’t short anything. We connected the black to the negative output and the red to the positive output on the power supply. We then adjusted the power supply potentiometer control to output 5vdc. It has a convenient LED display to let us know what the output voltage is. (Note: the knob was very sensitive, we ended up hot gluing it in place so it would stay at 5v). Also, the voltage will go down when it is under load. As long as it stays near 5v, you should be fine. Mine dips down to 4.92 volts dc at times.

After we had this setup, we could power the Raspberry Pi. This post won’t go into details about installing an OS onto the Raspberry Pi, however, you can read more about that here. I got mine setup with wireless with a static IP, that way I could secure shell (ssh) into it from my machine.

Next, we want to setup the switch so that when someone hits the doorbell, it will play a song for us. This is the mock up my father came up with (that’s an EE for you) to describe to me how this would work.

Here’s a circuit diagram of how the various bits and pieces go together.

In order to get this to work, we need to sense the button push on the Raspberry Pi. On Raspberry Pi’s they have what’s called GPIO (General Purpose Input/Output) which are header pins on the board. These can be used for things like installing LED displays on top of the Raspberry Pi’s, and specifically for us, a simple sensing circuit. You can read more here. I found this tutorial very useful in learning how to use Raspberry Pi’s GPIOs. This picture specifically really helped:

https://www.raspberrypi.org/learning/burping-jelly-baby/worksheet/

Raspberry Pi’s have two different schemes for identifying the GPIO on the board: Physical Pin Out and GPIO Pin Out. The one we are using is listed in the tutorial (GPIO Pint Out). In order for this to work, we want to connect the 5V (First pin on the right) and the GPIO 23 (8 Pins down on the right). The Raspberry Pi’s have built in pull up/down resistors, so we can use these to help us sense when the doorbell button is pressed. We used the jumper wires we bought to connect the wires running to the outside doorbell switch to the GPIO pins we described above.

Raspberry Pi 3 with the jumper installed on the GPIOs and power from the step down.

Once we have this all setup, we can now begin to test if we are receiving a button push from the doorbell. Here is some sample code I wrote up for debugging to see if we got a button push:

Sample code for detecting a doorbell press.

After you detect the button press, you can use this code in order to play an mp3. In order for this to work, you need to install the mpg123 package on Ubuntu (apt-get install mpg123.)

Below is the code for the full doorbell Proof of Concept (POC). I will add here that I had some false positives, even with the pull down resistor set (Raspberry Pi’s have these built in.) In order to stop from getting random doorbell rings (Who wants that happening at 1 AM?) I found this article on stackoverflow for a debounce function.

Full code for ringing the doorbell and playing the mp3 file.

If you’re using USB speakers, I recommend looking here as I encountered some problems getting my sound to work. I had to change the file /etc/modprobe.d/alsa-base.conf to reflect:

options snd-usb-audio index=0

Then I had to reset the Raspberry Pi in order for this to take affect.

I added this line to my crontab so that the python script would start on boot:

@reboot python /home/pi/doorbell.py &

After you’ve completed this you can now download your favorite mp3 and have it play whenever someone rings your doorbell!

Here is the article my father wrote up on making an enclosure for the speakers, so you don’t have some ugly implementation of wires hanging out of your wall.