Playing the Simpsons Theme on an Arduino

July 4, 2016 · 9:43 pm

Cake Pops!

Well, actually, cake pop stands. My wife Stephanie is the one that makes the cake pops. I just make the things to display them with. This past weekend, our friends Warren and Kaitlin were married, and they asked Stephanie to make some cake pops for their reception. In turn, Stephanie asked me to come up with a classy way to present the cake pops. This is what I came up with:

There are around 55 cake pops in a batch, and Stephanie planned to make two batches, so I wanted enough space to display 100 treats at once. I settled on five trays, each large enough to hold 20 cake pops. The final dimensions would be 6″ by 7.5″, with a matrix of evenly spaced holes centred 3/4″ from each edge. These dimensions meant that each hole would be 1.5″ from each other hole, which suits the average diameter of a cake pop perfectly.

I started off with a 1″ x 10″ x 6′ length of clear poplar stock from Home Depot. Because the lumber industry doesn’t understand that numbers have meanings, the actual dimensions of this piece were 3/4″ x 9.25″, which left plenty of stock to cut my five 6″ by 7.5″ rectangles.

On each piece, I marked out a grid for the holes

Since I don’t yet own a drill press, I took a trip out to my parents’ place to borrow my Dad’s. It was the perfect tool for the job, and allowed me to drill a hole at each intersection that was perfectly perpendicular to the piece, and the correct depth to boot.

The diameter of each hole is 5/32″, which is just a bit tight for the sucker sticks that Stephanie intended to use for her cake pops. Later on, I’d end up reaming each of the holes out just a bit to ensure that the sticks could slide in and out of the holes with ease. Unfortunately, the next size up in my drill index is 11/64″, which was a bit too loose for this application.

To add a bit of detail to the face of each stand, I decided to chamfer each hole with a countersink bit. Back in my shop, I used my router to add a 45 degree chamfer to the edges of each tray. They’re simple touches, but in my eye, they add a bit of detail that really cleans the pieces up.

After a good sanding down to 220 grit, I finished the trays with two coats of butcher block oil, sanding to 400 grit in between coats.

Following the manufacturer’s directions, I let the finish cure for three days to ensure that it was food safe before letting anybody lick it. As mentioned above, I had to bore each hole after finishing the pieces, because the oil caused the grain around each hole to expand a bit.

The pieces were finished in plenty of time for Saturday’s wedding, and even though I forgot to take a picture during the reception (in my defense, the lighting was poor, and well, I’d had more than a few beers), I did take this picture of one posing with the left over cake pops the next morning:

All in all, this was a really fun project. It only took me about a half day to complete (not including waiting for the finish coats to dry), and I’m really happy with how the trays turned out. They aren’t as tasty as my wife’s cake pops, but they do complement them pretty damned well.

My 12′ Long Workbench

When it came time to build a work bench for my brand new shop, I decided to go big. If you’re familiar with the much smaller bench that I built for my basement shop, the design of this project will be quite familiar. I’ve tweaked a few things here and there that I think will improve the end product, but at the end of the day, this is a fairly standard 24″ wide bench with a single shelf, built from plywood and 2x4s.

I started by squaring off the ends of four twelve foot long 2x4s. These will serve as the stringers for the bench shelf and top.

I decided to notch the stringers where each of the cross members attach. This helps to keep the structure square, and gives plenty of surface area for gluing and screwing the pieces together. Since the stringers are far too long to notch at the table saw, I used a 1/2″ straight cutting bit on my router. This simple jig clamps to the work piece and ensures that each notch is cut 1 1/2″ wide.

The first time I tried to use this jig, I got a little bit too ambitious. I set the depth of the cut to the full 3/4″, and tried to cut through two of the stringers at once. My poor old second-hand router couldn’t keep up, and the bit wiggled loose, tearing a deep gash into my workpiece. Lesson learned, I continued by cutting one notch at a time, and removed the material with two passes instead of one. It took longer, but the router appreciated my patience.

Here you can see one stringer with all of the notches cut, and the five perpendicular cross members inserted into them. Because the final width of the bench is meant to be 24″, and the notches are cut 3/4″ deep, each cross member is cut 22 1/2″ long.

Because the notches in each stringer are cut in the same place, the bench shelves come together very easily, and are almost perfectly square. I put wood glue and two screws on each butt joint between the stringers and cross members. This approach makes for really strong joints that will probably hold up for longer than I do.

With the cross members done, I cut four 24″ end caps at the table saw. Each end cap has a 1 1/2″ notch cut out of its end that is 3/4″ deep, just like the notches in the stringers.

Unlike the cross members, the end caps fit over the ends of the stringers.

With the skeletons of both shelves complete, it was time to attach some legs. Most garage floors aren’t level, and mine is no exception. I used a string line and a level to figure out the fall, and found that my floor drops 1″ over the 12′ length of the bench. As such, the legs closest to the far wall are 36″ tall, while the legs closest to the camera are 37″ tall. This results in a bench with level shelves that can’t really be moved out of the back corner that I’ve built it for.

Once the legs were on and the two shelves were attached to them, I sheathed each shelf with 1/2″ sanded fir plywood. I had to use a jigsaw to notch the holes out for the legs. The plywood added a lot of weight and rigidity to the bench, and at this point, it really started to feel like a hefty piece of shop furniture.

Once the bench was complete, I gave it a quick once over with my palm sander, and brushed on a coat of Minwax Indoor/Outdoor Helmsman Spar Urethane. Even though I fully intend for this bench to get beat to hell, I wanted a finish that would help to protect it from spills and tool scratches. The brush on product is much thicker than the wipe-on polyurethane that I’ve used in the past, and the satin finish that I chose looks great on the raw wood.

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February 4, 2016 · 8:39 am

The Brand New Workshop

When we bought our house in June of 2015, my wife and I knew what kind of home we wanted. Sure, we took some time to tour other neighbourhoods and walk through houses from different eras, but almost from the beginning of the process, we knew that we wanted a brick home that was built in the early decades of the last century. The place that we settled on was built in 1927 and is in wonderful condition, thanks in no small part to the work that the previous owners put into it.

The house sits on a decent sized lot in an old neighbourhood with large mature trees. To the back of the house, at the end of the driveway, there’s a detached single-car garage. It has not been taken care of in the same way that the house has.

It was pretty clear to us that the garage was going to need some work, but we weren’t sure what to do with it. The building was structurally sound, but it needed a new roof, new exterior siding, new doors, and new windows at the very least. It wasn’t insulated, and there was no electricity running out to it, so it wouldn’t really be a useful space after dark or during the winter.

In the weeks after the move, I set up a basic workshop in our basement. We have a large room down there that worked well, but the noise and dust got on my wife’s nerves, and moving stock in through the side door and down a narrow set of stairs was a pain. Soon enough, I had decided that the garage would become my new workshop.

In August, I worked with my father in law to rip down the lean-to behind the main garage. It had been used by humans as a garden shed, and by squirrels as a winter home for years, and was in bad shape. In September, we put a new roof on the garage, and I replaced the fascia boards, which had long since rotted through.

Come October, it was time to start on the interior. I had an electrician run a couple of spare circuits out to the garage, and finally got some light and receptacles into the building. With power in place, the work could begin in earnest.

The first job was to build a ceiling. In the image above, you can see new ceiling rafters that I installed at 8′ above the floor. It was challenging, in no small part because the floor isn’t level. As such, I had to choose a place to use as the measurement point, and then hang the rafters relative to that point using a plumb bob and a level.

In the image above, you can also see my first attempt at insulating the ceiling. I ended up pulling most of that insulation down, because the area between the ceiling and the roof is meant to be cold. Instead, I put the bats of insulation in the flat part of the ceiling, leaving the sloped bits above the rafters uninsulated.

With the rafters up and the building properly insulated, the next step was to sheathe the walls with 1/2″ OSB. Since the space is meant to be a workshop, I decided to use plywood instead of drywall, as I figured that it would take more abuse over the long term.

Given the age of this building, I suppose it should be no surprise that none of the corners in it are square, which made cutting the sheets of OSB to fit very challenging. You can see some gaps in between the sheets that I couldn’t manage to massage out, regardless of how much swearing I did.

Even though they were small, the gaps between the sheets really bothered me, especially in the corners where they were particularly bad. Since I couldn’t get the sheets of OSB to fit correctly, I decided to apply liberal amounts of spackle to the issue. Once sanded and primed, the room started to look really great.

I finished the room with a coat of grey paint. With the painters’ tape removed, the room really started to look like a real space.

To be honest, I’m still kind of surprised at how well it worked out. After all, I spent every weekend working on the project over a span of four or five months, and at times, it definitely felt like it would never be finished.

I still need to replace the doors, windows, and exterior siding, but those jobs can wait until next summer. For now, I’m just happy to have a working shop again.

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October 24, 2015 · 3:50 pm

Installing ROS on a Raspberry Pi

As a lover of technology, I tend to accumulate bits and pieces of interesting devices. Usually, these are purchased for use on unrelated projects, and on occasion, I have the opportunity to bring them together into a single project in a previously unanticipated way. Such is the case with my Arduino and Raspberry Pi. Both are interesting microcomputers with their own strengths and weaknesses, so it was when I learned that they could be made to work together with the help of Robot Operating System, I had to give it a shot.

ROS is an open-sourced project that is dedicated to providing a framework of libraries for performing common tasks under the general heading of robotics. It also includes drivers that allow you to easily interface with common hardware. The core of ROS is a reactor model of observables and observers that send messages to one another, typically over a serial connection, allowing any number of controllers to interface with one another and form a unified whole.

The rosserial_arduino library is a project that allows ROS on a Raspberry Pi (or other *nix device) to interface with an Arduino over a USB serial connection, thereby combining the computing power and versatility of a Linux-based microcomputer with the IO capabilities of an Arduino.

What You’ll Need to Get Started

Raspberry Pi 2 Model B
RealTek #814B Mini WiFi Module
8GB or greater MicroSD card
USB A/Micro B cable to power the Pi
HDMI cable
Mouse and Keyboard for controlling the Pi
Monitor or TV that accepts an HDMI input
Computer with an internet connection and an SD card slot

Installing Raspbian on the Pi

If your Pi already has an operating system on it, you can probably skip this step. If, however, it’s straight out of the box, you’ll need to install the Raspbian distribution.

As of this writing, the latest version of Raspbian is Jesse, released in September of 2015. I wasn’t able to get ROS working with this version, and backed down to the Wheezy release from May of 2015 instead. To install the operating system, I did the following:

Download the Raspbian Wheezy image via a bittorrent client.
When the download is complete, follow these instructions to copy the image file to your MicroSD card.
Unmount the card, insert it into your Pi, and hook up the power. Your device should boot into a command prompt. From here, you can run raspi-config to customize the installation, or get right to installing ROS.

Once the installation is complete, be sure to check for updates:

pi@raspberrypi ~ $ sudo apt-get update
pi@raspberrypi ~ $ sudo apt-get upgrade

An up to date system is a safe system.

SSH

Once your Pi has an operating system, you can switch to interacting with it via SSH. My TV is the only “monitor” in my house that has an HDMI input on it, so SSH works much better for me.

Make sure that sshd is running on your Pi:

pi@raspberrypi ~ $ sudo service sshd status
● ssh.service - OpenBSD Secure Shell server
 Loaded: loaded (/lib/systemd/system/ssh.service; enabled)
 Active: active (running) since Thu 2015-10-08 12:17:06 UTC; 4 days ago
 Main PID: 506 (sshd)
 CGroup: /system.slice/ssh.service
 └─506 /usr/sbin/sshd -D

If everything is working, you should see the text active (running) in the result. Once we know that an ssh server is running, we can check our ip address with the ifconfig command. The output should look something like this:

pi@raspberrypi ~ $ ifconfig
eth0      Link encap:Ethernet  HWaddr b8:27:eb:b9:49:cd  
          inet addr:192.168.0.109  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:5150 errors:0 dropped:51 overruns:0 frame:0
          TX packets:565 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:552488 (539.5 KiB)  TX bytes:60766 (59.3 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1104 (1.0 KiB)  TX bytes:1104 (1.0 KiB)

If your Pi is connected to a LAN cable, you’ll want to look at the eth0 section. If it’s connected to WiFi, look for a wlan0 section. Both sections should have an inet addr field whose value starts with a 192.168.x.x address. In my case, it’s 192.168.0.109. From a terminal on my computer, I can connect with:

jfritz@IDEAPAD-UBUNTU:~$ ssh pi@192.168.0.109

When prompted to accept the Pi’s RSA key, I do, and when prompted for a password, I enter the default password raspberry. If you intend to leave the Pi connected to your network for long periods of time, you should change this password or add key-based authentication to the system.

If you have problems getting connected, check out the official instructions on the Raspberry Pi website.

Installing ROS on the Pi

As of this writing, the most recent version of ROS is Indigo, released in July of 2014. To get it running on the Pi, you’ll want to follow the official ROSberryPi installation instructions on the ROS website.

While following these instructions, I had a few false starts. It’s important to read the instructions carefully, as they’re fairly generic, and can be used to install different configurations of ROS on different versions of Raspbian. I found that the instructions for the ros_conn configuration worked best on Raspbian’s Wheezy release.

The trickiest part of the instructions is section 2.2 Resolve Dependencies. It took me a couple of reads to realize that if you’re installing ROS Indigo’s ros_conn configuration on Raspbian Wheezy, you only need to compile two packages from source: libconsole-bridge-dev and liblz4-dev. Installing any other packages at this step just costs you time, and may introduce problems down the road.

I also found that the install process went much smoother when the Pi was connected to a LAN rather than WiFi. The WiFi signal in my house is relatively weak, and the Realtek #814B is really cheap, so downloading a lot of files while maintaining an SSH connection is a big ask.

Once the installation is complete, open up your ~/.bashrc file, and add two lines to the end:

# export ROS environment variables
source /opt/ros/indigo/setup.bash

This will make sure that the appropriate environment variables are set to interact with ROS on every startup. You can check that it worked by rebooting your Pi and running

pi@raspberrypi ~ $ printenv | grep ROS
ROS_ROOT=/opt/ros/indigo/share/ros
ROS_PACKAGE_PATH=/opt/ros/indigo/share:/opt/ros/indigo/stacks
ROS_MASTER_URI=http://localhost:11311
ROS_DISTRO=indigo
ROS_ETC_DIR=/opt/ros/indigo/etc/ros

If you see all of the ROS_* environment variables print out, then everything is set up and ready to go. Now it’s time to start on some tutorials.

Eventually, I want to get the Raspberry Pi communicating with the Arduino, and use the latter as a sensor platform and motor controller for some kind of a robot. For now, I need to find my way around ROS.

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September 7, 2015 · 8:36 am

Building Milk Crate Sized Boxes for my Record Collection

I’m a hipster. Seriously. I have a beard, I’m a foodie, and I collect vinyl records. After moving into my new house, I realized that I needed a new place to store the aforementioned record collection, as the bookshelf that it previously lived on is now on a different floor than the record player, and I’m too lazy to walk up and down stairs every time I want to listen to a record.

This project, as many woodworking projects do, started out with some wood:

One of my goals for this project was to learn how to create a box joint, which is a method of joining two orthogonal pieces of material together by way of cutting a bunch of fingers into each piece and interlacing them, providing a large surface area for glue to adhere to. The result is an extremely strong and handsome joint, but the method requires the sides of the box to be cut longer than you intend them to be.

In general, if all of your material is the same thickness, then each piece needs to be cut two thicknesses longer than you intend its inside dimension to be once joined. My boxes have an outside dimension of 17″ by 14″, but their inside dimensions are only 15.5″ by 12.5″, because my material is 3/4″ thick. If I were joining the sides with a simple butt joint, and the front and back pieces of my box sat between the two side pieces, then the front and back pieces would have to be two thicknesses shorter than the final width of the box. With a box joint, all sides are cut to the intended final outside dimensions of the box, because the interlacing fingers will eat up the extra length. Therefore, the front and back of my box are cut 14″ long, while the sides are cut 17″ long.

Box joints can be cut by hand, or by hogging material out with many passes across a standard table saw blade, but these methods make it hard to keep the fingers and the spaces between the fingers the same width across the entire length of the joint. Instead, I purchased the Freud SBOX8, a table saw blade specifically made for cutting 1/4″ or 3/8″ box joints. It’s basically a dado blade with only two widths that cuts a flat-bottomed channel.

In addition, I built a simple jig to help keep the spacing between fingers even:

This jig is basically just a mitre sled with a 3/8″ square piece of hardwood affixed 3/8″ away from the edge of the blade channel. When cutting the fingers of the box joint, you advance the piece along the jig by fitting the previously cut finger over top of the guide piece, which ensures that the next finger will be exactly 3/8″ away from the previous one. This in turn results in fingers and spaces between fingers that are all 3/8″ wide.

In the photo above, you can see that I use my jig to cut two sides of the box at once. Any two sides that join at a 90 degree angle can be cut this way, but they need to be offset by one finger width (in my case, 3/8″) so that the tops of the two pieces will be flush when the fingers are meshed together.

After making a great deal of sawdust, I ended up with all four sides meshing nicely:

The next step was to glue the sides together. The wood glue that I typically use has a working time of around 15 minutes. For a project with this many glue surfaces, I’d recommend finding a glue that takes longer to set up, since it takes awhile to get all of the surfaces covered in glue, and you do want to glue the entire box together in one operation so that you can ensure that all of the pieces are square to one another. Many clamps are essential for this process.

With the glue dry, I used a palm sander and a router with a flush trim bit to clean up the edges of the box as well as any areas where the fingers sat proud of the side of the box. I also used a jig saw to cut some handles into the front and back sides.

The last step was to put a bottom on the box. I used a router with a rabbeting bit to cut a 1/4″ channel around the inside edge of the bottom of the box, then glued in a piece of 1/4″ thick plywood.

Finally, it was time for finishing. This project got one coat of Minwax Pre-Stain Wood Conditioner, two coats of Minwax American Chestnut Gloss stain, and three coats of Minwax Wipe-on Polyurethane. Before staining, I sanded down to 220 grit, then hit the surface with triple-zero steel wool between each finishing coat.

In the end, while the finish is smooth and glossy, I think it came out too dark. I really liked the look of the box after the first coat of stain, and if I were doing the project again, I would probably would stopped there.

I really liked the look of the finger joins with just one coat of stain

The finished look is nice, but a bit orange for my tastes. I think the polyurethane has a lot to do with that yellowing effect.

After a lot of hard work, many mistakes, and more than a few false starts, I triumphantly carried my new record crates upstairs and started to put my records into them… only to find out that they wouldn’t all fit. Fuck.

You know that old adage about measuring twice and cutting once? I measured twice, but I only measured a single-platter record sleeve, not realizing that gatefold sleeves and record sleeves that contain two platters are wider than their single-disk counterparts. Luckily, my wife had the bright idea of putting the records into the boxes sideways. It looks a little funny, but it works:

The only problem is that my collection doesn’t have much space to grow. I guess I’ll have to make more boxes after all. Oh well. Back to the shop with me.

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August 1, 2015 · 7:35 pm

Playing the Simpsons Theme on an Arduino

A little while back, I picked up an Arduino Starter Kit. It contains an Arduino Uno, a bunch of common components, and an instruction book that walks beginners through building circuits and using the Arduino to interact with hardware.

One of the projects in the book is a basic synthesizer that lets you play tones on a piezo speaker. The schematic for this is dead simple:

After getting the Arduino to play a few notes, I decided to extend the project a bit and play a melody. After a bit of screwing around, I managed to get the thing to play the Simpsons theme.

The code for this sketch can be found on GitHub.

Building a Rubbermaid Friendly Shelving Unit for the Basement

I built a hefty 8’x2′ shelving unit for my basement for about $100. This is the corner that the shelf was built to fit into, with a 2×4 for scale. I would have used a banana, but we’re fresh out.

This simple mitre sled jig made cutting the pieces easy.

The block on the table saw fence sets the length of the piece that I’m cutting, but stays out of the way while cutting to avoid kickback.

The block on the mitre sled acts as a feather board, keeping the stock pressed firmly down while cutting. This really helps with longer pieces.

Each shelf consists of 1/2″ plywood over a simple 2×4 frame. The front and back are 96″ long, the end caps are 24″ long, and the middle supports are 21″ long.

In this shot, you can see that my basement floor is about 3″ out of level over the 8′ length of the piece. I propped it up with shims, then screwed on some temporary legs once it was level. This gave me a level surface to base the rest of the build on.

Next, I attached the five main legs. Each leg is a different height to account for the slope of the floor. The end result is that all of the legs are the same height relative to the shelves

With the legs attached, I built the second shelf in the same way as the first, and prepared to attach it to the frame.

To help with positioning, I clamped scrap blocks at the appropriate height on each leg. This gave me something to set the shelf on before I screwed it in place.

Note that from this point forward, all height measurements were taken from the bottom shelf, rather than from the floor.

With the guide blocks in place, the second shelf was easy to install.

The third shelf was installed in much the same way as the second.

I built the fourth shelf in place, because I was working alone and didn’t feel like throwing out my back while lifting it into the air. I used temporary blocks to position the middle supports at the correct height.

The top two shelves are half the height of the bottom two, since big stuff tends to be heavy, so it makes sense to keep it near the bottom.

The bottom shelves can accommodate a large Rubbermaid or two small Rubbermaids stacked on top of one another. The top shelves can accommodate a small Rubbermaid.

I had bought some hardware to lag the unit to the wall, but it’s heavy enough that I have to put my full body weight into moving it, so I don’t think it’s going anywhere.

Building a 2×4 Workbench for my Shop

This summer, we moved out of our apartment and into our first house. Although the house is in good shape, there is some work that needs to be done, so one of the first jobs was to set up a workshop space. It’s nice to have somewhere to store my tools instead of being confined to the corner of a closet.

If you’ve never built anything before, don’t worry. This bench is easy to make, and only costs about $50 in materials. It’s made of 2x4s, and you just need four of each length, plus a half sheet of good one side plywood, cut into two pieces about 2′ by 4′.

Start by cutting the frame pieces out of the 2x4s. My legs are 36″, my front and back stringers are 46″, and my side stringers are 23″.

I assembled the front and back first. Each consists of two legs (the vertical pieces) and two long stringers (the horizontal pieces).

I attached all of the pieces of the bench with 2 1/2″ screws. Because I was screwing so close to the edges of the wood, I was sure to pre-drill the holes. It’s important to make sure that the edges of each corner that you drill are flush.

I marked out where I was going to drive in my screws. An inch from each edge is good.

To start with, only drive one screw per corner. This will allow you to push everything into square before driving the rest of the screws and locking the joints into place.

If the piece is square, then the distance from each top corner to the opposite bottom corner will be the same. If it’s out, just push the stringers in opposite directions until everything lines up.

Once the piece is square, drive the other three screws into each corner. This will lock all of the angles in place.

Once the front and back are built, it’s time to attach the side stringers. I stood the front on end and clamped the side stringer to it so that I had both hands free to drive the screw in.

Same as before, only drive one screw per corner to start. Because the screws for the front stringers were one inch in from each side, I put the screws for the side stringers 3/4″ in from each side.

Once the side stringers are attached to the front and back of the bench, it’s time to bring the two pieces together. Now it’s starting to look like a bench. An upside down bench, but a bench nevertheless.

Again, square everything up, and then drive the rest of the screws in to lock the angles.

After flipping the bench over, I put the top on. I used a 2’x4′ sheet of 1/2″ GIS plywood for the top of my bench. The size of the frame gives me an inch of overhang at the front and on both sides.

The top is affixed to the bench with 1 1/4″ screws. I chose to countersink the screws around the bench top so that they’re flush with the work surface.