Salvage – It’s Not Just for Sinking Boats

What do you do when your beloved printer, scanner, blender, or remote controlled car breaks? I’m glad you asked because this weeks’ post is about salvage. I’m going to use my experience to help you quickly sift through the junk and help you find the good stuff.

sal·vage

( sal-vij )  – To rescue or save from fire, shipwreck, danger, etc.

In this sense of the word, I mean “to rescue the engineering from broken devices.” I know that seems a simple, but confusing turn-of-phrase, but I’ll break it down into two parts. First, I disassemble broken devices or more broadly, devices that people don’t want any more, so I’m not contributing to waste and I’m squeezing just a little more utility out of it than it would normally have. Second, I’m taking away from the device the engineering knowledge that I can glean from the arrangement of parts and the parts themselves to use in my own projects. From when I was a kid, I thought taking things apart was kind of a puzzle and still do. Since I’ve earned my degrees in engineering, I also look at each product I disassemble as a lesson in ‘continuing education’.

wpid-img_20140724_190319.jpgAmazing Little Peristaltic Pump Salvaged from an Inkjet Printer

You wouldn’t think about it just by looking, but a lot of engineering goes into the devices we use on a daily basis. Take a ‘simple’ motor for example, its an assembly of no fewer than 6 different materials brought together using additive (casting), subtractive (punching, machining, and polishing), and forming (sheet metal rolling, bending, and wire winding) methods which takes into account electricity, magnetism, thermodynamics, fluid dynamics, and mechanics. So why did the engineers that brought this product together select this motor? What are its special properties? Is it fast? Lots of torque? High voltage (low current)? What about the arrangement of the components? What decisions did the designers make to save money? What cleverness went into making the movement? What about specialty materials like the nichrome wire in toasters? I ask these questions almost reflexively when I take a look ‘under the hood’.

wpid-img_20140723_062032.jpgPrinter / Scanner Combo Destined for the Trash

To help illustrate the process I use to salvage, I’ll refer to a tear-down I did recently of a HP combination inkjet printer and scanner that had stopped printing, given to me by my friend Farzan.

Before I start taking a product apart, even before I bring it home, I try to figure out what parts I’m going in for. Lets face it, with places like Best Buy taking old electronics to recycle the e-waste, it’s far better for the environment to take it in than take it apart. (Maybe a peek inside the case before you take it in wouldn’t hurt) At the same time, also learn to recognize when something has no redeeming value and send it on its way. With the inkjet printer, I was sure from my experience stripping down other flatbed scanners that I’d find at least one stepper motor inside, a linear guide, and maybe a photogate or two. Knowing what you expect to find will inform how aggressively you can take the product apart. What I actually got out of the inkjet printer leads me to salvaging lesson number 1: When you salvage for parts, you don’t always get what you were expecting.

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DC Motor with Integrated Encoder
Strange USB Adapter and Wifi Card

I was really just blown away by how many interesting, useful things I was able to get out of this printer/scanner: 3 motors (1 with a linear drive belt and another with a built-in encoder), a fully enclosed dual-voltage 12V & 32V power supply (low current), screen with faceplate and bevel that I might be able to repurpose, peristaltic pump with bleed valve and drive gearing, wifi adapter card for experimentation (maybe), springs, rollers, USB cable adpater, button-cell battery holder, several photo gates, a pane of glass, and an SD card adapter. I already have two projects in mind using some of these components.

Always exercise caution when taking an unknown device apart. Since you didn’t design it, you have no way to know what’s in it. The watch-outs I’ve seen are: springs that are stretched or compressed, so they go flying when they slip, unknown lubricants that get everywhere, glass and other pointy / sharp things, and the occasional glass tube filled with a gas. Especially when taking apart flatbed scanners, take care with the lightbulb which I think has mercury in it, but is only marked with the “Do not throw away” symbol. As a mimimum, I recommend safety glasses, but gloves and a well-ventilated area might also be a good idea. So, salvaging lesson number 2: Safety first… even though it’s mentioned second.

wpid-img_20140724_180635.jpgAlways Check Under the Stickers for Those Last Few Screws

Disassembly seems pretty straightforward, but a lot of the ease I have comes from experience. Over the dozens of products I’ve disassembled, I’ve dealt with glues, screws, tabs, catches, springpins, retaining rings, and press-fits, so I know how to recognize how a thing is held together. If you want the product to go back together, start your disassembly process with some pictures and continue taking them throughout. Next, if you’re salvaging for parts, I recommend only taking one part off at a time, when you do that, you get a better understanding of how the parts went together. Start by removing the screws because they are always obvious, but look before you pull pieces apart. A lot of the times, screws are used with tabs or slots or other things that make it easy for the assembly line worker (or robot) to slap parts together, but not easier for you to take apart. On the printer, for example, there were some screws hidden under stickers and some removable components.

The first question I ask myself when I get a device open is “How does this thing work?” Seeing how the components are arranged and how they work together will help you understand the general operation of the device. This will help you figure out which parts you want to keep, find the parts you want, and help you understand the decisions that went into the design.

During this ‘inspection phase’ is where the whole thing becomes a fun puzzle for me. Did the designer make the same arrangement choices I would have? Did they choose the same kinds of parts I would have chosen? Why is that part black and the others white? Is there something special about that connector or this wire or the thickness of the plastic? In general, recognizing differences and figuring out why it’s different is the name of the game. I found a lot of interesting things inside the HP printer. It had a peristaltic pump I wasn’t expecting, included no stepper motors (I was shocked), had a fully-enclosed DC power supply inside the printer case (like Russian nesting dolls), and had a USB jumper that went from a mini B USB port on the board to the standard B port on the case. All of these things were very surprising. I was also in awe of the sophisticated mechanisms used to drive the printing process: I found that through a set of clutches and sliders, the two motors in the printer were able to control two discrete roller movements to draw up the one sheet of paper and keep it moving smoothly past the print head while in a completely different mode, drive the peristaltic pump to (I assume) clean the print heads when they are in the home position. Just remarkable! That makes lesson number 3: If all you get out of a disassembly is the knowledge of how things are put together, then you win.

wpid-img_20140723_062901.jpgNatural Environment of DC Motors

Once you’ve convinced yourself that a part is useful, make sure to take a picture of it in its ‘natural environment’ before diving in. This reference will be a huge help later when you try to build with it. Also, consider what components are upstream and downstream of it. I pulled several motors out of the printer and with those, I had to consider if there was a motor controller built into the circuit board for me to use or if the mechanical linkage on the shaft was useful. Finally, after you pull the component out, make sure you don’t have to save the mounting hardware. I’ve spent many, many hours trying to find the right screw to fit the thread pattern and length on the end-cap of many DC motors, so take some advice and save the mounting hardware. Lesson 4: Save the screws.

After you’ve learned all you need to learn and taken all there is to take, what happens to the left-overs? Depending on what was removed and how much is left, there are lots of options. Generally speaking, I want to consider the environment as much as possible, so my hierarchy for disposal is: reuse, recycle, and then toss if you have to. In the case of computers and peripherals like this printer, if you only take one or two things like a motor or something, you can still button it all back up and turn it in at places like Best Buy and they’ll recycle the e-waste. If all you have are a few body panels, it would be okay to recycle them or throw them out if necessary (that’s what would happen to them if they went to Best Buy anyway). Take care not to throw out anything hazardous like that mercury lamp I mentioned earlier or batteries, etc. For those, check with your waste management company to find out how to dispose of those properly.

That was my project day, how was yours?

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A Twist to Build a Dream On

Some projects, like this deburring/countersinking tool sit on the back-burner for a long time. Dusting them off to finish the job feels like sharing a meal with an old friend. This deburring tool is a handy way I came up with to reduce the amount of time I spend switching between drill bits and countersinking tools to make clean holes in my metal projects.

As many handymen, handywomen, and fabricators know, deburring drilled holes makes them look smooth and professional quality. One way to get a good deburr on a hole is to use a countersinking bit in your drill to just graze the lip of the hole. The problem is that it’s a pain to swap out the drill bit for the countersinking tool. However, there is some relief from the tools already available. There are general deburring tools, speed deburring tools, or manual-style deburring tools shown below. But why buy a tool when you can make one that’s better?

Outside ImageOutside ImageOutside Image

General Deburring Tool, Speed Deburring Tool, and Manual Tool

 This project started with a Yankee push drill. Basically, it’s a manually powered drill that turns the tip as you push down on the handle. The downward force is converted into twist by a mechanism with a steep-angled screw at its core. The chuck is designed to hold the small drill bits that come with the tool. Obviously, the small diameter tools won’t deburr anything very well, so I decided to swap it out for something more useful. I found this countersinking bit and quick-change chuck at Harbor Freight that would work out nicely.

IMG_2556Quick-Change Chuck found at Harbor Freight

IMG_2566Hand Sketch of the Internal Mechanism of a Yankee Drill

Before I disassembled the drill, I had to figure out how it worked so I wouldn’t compromise any critical features of the drill when I modified it.  I made a sketch of what I found, shown above. The modification was easily done by drilling out the rivet holding the chuck in place, then using a lot of leverage to remove the press-fit chuck. (this drill was very well-built).

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Drill Press, Chuck, File for Roughing, Sand Paper for Finishing

The internal diameter of the yankee drill was 0.34″, but the Harbor Freight chuck was 0.43″, so I had to turn it down some. I reduced the diameter of the quick-change chuck using my drill-press and a file. The slowest my drill press can go is about 550rpm which was fortunately slow enough to keep the file and chuck from overheating. I used a spring-pin to fix the chuck to the yankee drill and voilà! a new tool is born!

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Finished Yankee Deburring Tool

That was my project day, how was yours?

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Thinking Outside the Box Inside a Box

Sometimes the thing you need doesn’t exist in the world. However, you don’t have to use off-the-shelf things only in the way they were intended.  Don’t be afraid to turn them upside down, inside out, or just take it apart to see what else you can use from it. 

Clamshell box half openCryptex Box Half Open

Before we dive too deeply into this project, let me tell you a little bit about me. I find boxes fascinating. I suppose you could say I’m actually fascinated with treasure and the prospect that a box might hold treasure makes it mysterious and alluring and almost magical. And like Schrödinger’s cat, you don’t know what’s going on inside until you open the box and take a look. This is one of the reasons I love the cryptex from Dan Brown’s mystery novel The Da Vinci Code. In the book, the cryptex is a puzzle box, shaped like a cylinder that contains a scroll with a secret code. (so mysterious!) The movie adaptation of the Da Vinci Code was released to video in 2006 and with it was also released the special edition giftset which included a miniature, working cryptex replica. I got one of these, but was uncertain what to do with it once I had it. Unfortunately it just rolls right off of any table you put it on.

The idea for this project was to build a box that I could use to hold the cryptex to keep it clean, but the box also needed to have a shallow bottom so I could open it to display the cryptex when I wanted it out. Every box I looked at had the opposite; a deep bottom and a shallow top. The wooden project boxes from my local craft stores were the perfect size, but I wasn’t satisfied with having the cryptex out of the box for display. Instead, I chose to flip the box upside-down to use the lid as a cradle for display and split the (former) bottom in half to make two clamshell doors.

Project Box closedProject Box Open

Example of Craft Store Project Box

The conversion was really easy, but here are a few tips: on the second door, I had to install new hinges to match the existing ones and that meant cutting notches so they could be recessed. Make sure to cut the notches to the right depth! I used a box saw with a guide to cut the bottom of the box in half. This kept my cut straight and parallel to the sides of the box. Also, stain doesn’t work out with these premade boxes because the glue they use to hold the sides together creeps into the grain of the wood, so it won’t take stain. To finish the build, I glued small, cylindrical neodymium magnets in the walls of the two doors. This makes them snap together and hold fast without a visible catch.

Clamshell Box Fully OpenClamshell Cryptex Box Fully Opened

I thought that the painted look was not quite fitting with the brass and white look of the cryptex. Instead of that solution, I tried something new; I tried to stick paper to the walls of the box. There are a ton of textured papers in your local craft store in the scrapbooking section. I chose a red velvet material for the interior and rough gold for the exterior. the rough gold hides the creases and seams in the paper and the velvet gives the air of sophisticated opulence.

Gold PaperRed Velvet

Example of Gold Outer Paper and Red Velvet Interior Paper

To get the paper to fit perfectly, especially on the interior, I had to draw stencils of the shapes I wanted to cut from the scrapbooking paper with a much cheaper, easier to work with material. I used printer paper to make mock-ups of the shapes. I cut them out, then folded them to test fit the shape into the box. The trick here is to hide the edges of the paper in the creases in the corners. To do that, I made small flaps where two parts of the stencil would meet. The flaps had 45 degree corners to avoid wrinkling the paper in the corner. When I assembled the stencil in the box, I would tuck the flaps under the mating part and make the edge of the mating part lie perfectly inside the corner. This does two things: First, the flap completely covers the inside corner with the same uniform color as the rest of the paper material. Second, the edge of the mating part lies parallel with the inside corner and within it, so a casual observer will only see the crease of the inside corner and not the joining of two parts, making it appear seamless.

Stencil PatternExample of an Inside Stencil

There are other ways you can customize something from the shelf and make it into something that’s exactly what you need. These craft store project boxes are also really handy. I’ve used two or three of them in projects over the years and they really hold up in the workshop.

That was my project day, how was yours?

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Instant Parade!

This contraption is fun, in a box, with flags (Sheldon Cooper would be proud). The basic idea is, you can put flags for any occasion in the holders, push a button, and BAM! Instant fanfare with flags waving everywhere.

The Instant Parade was inspired by many things. The first and foremost was my wife. While stuck in traffic one day in her Scion Xb, we noticed that we had fallen in line behind another Scion Xb and she said “it’s like we’re in a Scion parade.” With that one statement, we had invented our own commuting game where we would exclaim “Scion Parade!” whenever we found ourselves in front of, or behind another Scion. This has since evolved to include the “Super Scion Parade!” for other Xb’s of the same color as ours and “Scion Mob!” if we find ourselves in a group of Scions. I also drew inspiration from the hit movie “Cloudy with a Chance of Meatballs 2” where Flint Lockwood would exclaim “Celebrate!” and his trained monkey Steve would hit the big, red button on Flint’s Party in a Box invention. The resulting explosion of colored paint, confetti, balloons, and stunned faces put us on the floor laughing. When we put those two things together with Independence day as an opportunity to try something new, the instant parade was meant to be.

Some important considerations for this project were that I wanted the flags to be changeable, so if we wanted to use it for the Super Bowl, the World Cup, or just in a Scion parade, we could. I needed the flags to wind up when they’re done waving around so they aren’t laying loosely on the table . Finally, the whole thing needed to be battery powered so I could take it with me on the go. After all, a parade isn’t a parade unless it’s moving.

Instant Parade Lego Prototype

Lego prototype

I started designing with a Lego prototype. This helped me figure out the layout of the mechanism and what would work and what wouldn’t. For example, the gears in the wind up mechanism would constantly slip teeth because the shafts were too loose, so I knew that I’d have to make the bearings with tighter tolerances.

IMG_2521 IMG_2516
IMG_2527 IMG_2525

Pictures from the build process

To build the frame, I used some scrap 3/16″ plywood material and some 3/16″ dowels. This allowed me to set the width between the two servo mounting plates as I went. I used two HS-485HB servos to wave the flags around and a hobby motor I took out of an old remote control car steering mechanism as the wind-up motor. The motor doesn’t have a lot of torque, so I had to change the gearing ratio from 10:1 in the Lego model to 1:3 in the final build. The bearing assemblies are made from 7/32″ OD x 0.014″ wall aluminium tube cut to 1.75″ fit inside a 1″ piece of 1/4″ OD aluminium tube with the same wall thickness. The center bore of the 30-tooth gears I used had to be reamed to 7/32″ (with a cordless drill and a drill bit) to fit on the 7/32″ tubing. I got lucky that my drill bit is just the right size so the gear has a snug enough fit that it doesn’t slip when the flags are being wound. Not all drill bits have the same tolerance, so if you’re not that lucky, maybe try again with a different drill bit on a different gear. With the 7/32″ sleeve and gear on the flag pole, I drilled two 1/16″ holes, one at either end and used solid 22Ga wire and some #10 washers to hold the 1/4″ tube captive, but freely rotating. Finally, I mounted the bearings on the servo horns with the mounting screws supplied with the servo and a rectangular piece of the 3/16″ plywood with a V-groove filed in it to keep it aligned with the outer bearing shaft. I had to take care not to over tighten the screws otherwise it would pinch the bearing and prevent it from rotating. The last part of the build is the rectangle of poster board I used as the trough to hold the flags when they wind up.

The servos and motor are driven by an Arduino Uno SMD. From the start of the program, the servos are at their home position in the poster board trough, then they dash to about 30 degrees, then wave back and forth using a sine function, giving the waving a natural fluidity. Each flag waves at a different rate to add some dimension to the motion. After a period of time, the flags return to their home position in the trough. The wind up motor then runs for a set amount of time and the whole thing just stops, waiting for the reset button to be pushed, starting the sequence all over again.

Instant Parade

Instant Parade!

Like any other project, there’s always things that can be done to improve it. In this case, I’d like to change the program so the dash to 30 degrees at the beginning and the return to home at the end are smoother and more controlled. This will reduce the current draw on my batteries and give the whole motion a more fluid, natural appearance. I also think the functionality of the Arduino is wasted on the simple requirements of this project, so I’d like to use a simpler microcontroller like perhaps the Picaxe-08M2. I think I can improve the winding of the flags by changing the shape of their trough. I’ll have to experiment to find out if this will work. Finally, I’d like to make a cover for the mechanism to give it a cleaner look and to make it easier to carry around with me.

That was my project day, how was yours?

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