Wooden Time Machine

I don’t know how to start this introduction, but the punchline is: If you don’t want to go broke buying picture frames made from reclaimed wood that is probably just chemically treated  new lumber, then spend between $10 and $20 and a couple hours making your own. I did and this is how I did it.

Very recently, I found that I needed a frame for an oddly sized poster. The image on the poster is an 1852 map of San Francisco. Since I’m not a fan of highly ornate antique styles (which I guess might have been appropriate for a wall-hanging object from the 1850’s), a rustic-styled frame was the clear choice since it would make the poster and frame seem like a “found” object. I looked into buying one, but the closest thing I could find to what I imagined were picture frames that looked like they were made from reclaimed wood, but they were so prohibitively expensive they would have cost several times as much as the poster. Since I’ve made a thing or two out of lumber, I knew I could make a frame. The trouble was, how would I get the lumber to look like I wanted? Thanks to the infinitely available information on the internet, I was able to easily find more than a dozen websites describing the process for “distressed” wood finishes and quite a few for “reclaimed wood” finishes. If you’re planning on doing a similar project, you should spend some time looking at the different ways that other people have done similar processes.

The website I used for reference described how to give boards an artificially aged look using three steps: paint the wood, roughly sand a majority of the paint away, then stain the exposed wood to make it look weathered. With this in mind, I bought a sample jar of paint in a light blue color that I chose to be close to the colors in the room. The sample jars of paint only came in flat which is fine because it doesn’t look shiny and new, but the paint will take the stain a little. I also chose a darker stain because I figured it would give the best contrast between the aged and worn and the ‘old’ paint. The stain I used is Minwax’s Jacobean which ended up being a little darker than I was expecting. Your mileage may vary, but I needed a little less than 16 feet of 1 x 2 lumber for my frame design. I chose a material at Home Depot called Trim board primarily because it’s not particularly expensive (20ft cost me ~$7) and also because a couple of the sides are pretty roughly cut. It’s so rough in fact, you’re likely to get a splinter just from looking at it. The roughness works to my advantage over a smoothly cut board because the paint will settle in the low points of the wood, making it easier to leave behind paint remnants when I sand in the second step. After the finish is complete, I’ll need nails and wood glue to hold the whole thing together. One trick I learned the hard way was if you’re going to use wood glue to hold parts together, do the surface finish first, assembly second. The glue chokes the wood grain which prevents the stain from taking hold and the finish will look like salt water dried on the glue joint.

Very Rough Lumber Sanded much smoother
Rough Lumber from the Hardware Store Much more suitable after some sanding

Even with a simple project like this, its best to work from a drawing or a sketch so you don’t get confused and cut the wrong board, so the very first thing I did before I put saw to wood was spend a little time making a post-it sketch. After cutting the boards to length, I spent some more time preparing the wood for the next steps. The little details that go into a project are surprisingly important to giving the finished product a believable appearance. For example, sharp edges and splinters make the boards look new, but breaking the edges and removing the splinters with rough grit sandpaper automatically makes them look older and more worn. As an added bonus, the splinters would have clogged my paint brush if they had stayed, so they must go. I know it must seem like a contradiction that I bought rough wood only to sand it, but I didn’t sand it completely smooth and if you saw how rough this wood is, you would understand completely. Even though I had more than enough paint 100% of the lumber many times over, I didn’t want to waste it (or my time), so I carefully picked which faces of the wood would be showing once the frame was assembled so I knew where the paint needed to go.

Paint

Full Paint Coverage Not Required

The next step is really easy: slop some paint on the boards and let them dry overnight. The next day, after the paint has completely dried, I used my orbital sander with fine grit sandpaper (the medium and coarse just take the paint away too fast) to work the paint and wood down until there were just remnants in the grain. If you take on a similar project, be careful to sand safely, but don’t be too careful in sanding uniformly because sloppiness will look like age and wear. I made sure to wipe, brush, and blow away the dust before I began staining to keep from cross-contaminating the stain in the can, but also I wanted the frame to look old, not dirty. There’s also one trick I remembered after I was done that I wish I had used here. Instead of just jumping straight into staining this very dry wood which soaks the stain up like a sponge: Spray some water over the boards and let it soak in, then wipe them off before getting started. The water will hinder the stain from setting in too quickly, making it easier to make the grain pop out like aged wood does without turning it all even and dark. I applied the stain, then immediately wiped it off. Because I didn’t do my trick with the water, it ended up a lot darker than I wanted, but the look grew on me. I found that the flat paint I used seemed to soak up some of the stain, but it makes even the paint look a little older, so maybe that’s a good thing, but it’s something to consider when picking your paint color. I let the stain dry out some before I started gluing parts together.

Paint mostly sanded

Painted and Sanded. Ready for Stain.

When I was ready to assemble, it went together in minutes. Just glue, and nail. Glue and nail. I used a sturdy, level table top to make sure the frame was flush as I assembled and a pneumatic brad nailer to fasten the pieces together. When the glue had dried, I attached a couple rings to the back to hang it on the wall and mounted the poster to the front with upholstery tacks that looked like hammered brass. The tacks fit the rustic look I was going for.  Then the most important step: hang and enjoy!

Picture Frame

Finished ‘Reclaimed Wood’ Picture Frame

That was my project day, how was yours?

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Build a Virtual Anything with Cardboard

What do you get when you combine two parts velcro, two parts magnet, two parts glass, and fold them into a little bit of cardboard? According to Google, that’s how you get a glimpse of the future… and the view is GREAT!

In June of 2014 at the Google I/O event, a team of three developers presented a simple DIY device that could transform your smartphone into a virtual reality headset which they simply called Cardboard. The presentation they gave (shown in the video below) demonstrates them using the cardboard hardware with a software development kit to build an app. The reality is, it takes a lot more than leftover shipping material to make your own Cardboard headset. The hardest part to source is the two biconvex lenses you’ll need to reduce eye strain. With the event long over and these lenses in high demand, you can find many versions of Cardboard as kits and they save you just enough headache to make it worth the extra cost. I got mine from DODOcase. The design is basically the same with perhaps a little less cardboard (the material) involved.

Google I/O 2014 – Cardboard: VR for Android

So, how did Google take a simple building material to make such an impressive device? I thought I’d never ask… The basic technology at work here is stereoscopic photography which is an optical trick that’s been around since before penny arcades. I remember being mesmerized by the picturesque landscapes of my View Master, which did basically the same thing. What happens is each eye is presented with one of a pair of pictures which are taken at roughly the same distance apart as your eyes. When you do that, your brain stitches the images together just like you were looking at it in person and PRESTO! you’re overlooking Niagara Falls from the comfort of your living room. Google then took that and added the accelerometer and gyro in your smartphone to allow you to move around within these virtual, stereoscopic pictures making them more immersive. They also use a magnetic field interacting with the hall effect sensor in the phone to give the ability to interact with the virtual space.

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The DODOcase Cardboard VR Toolkit Assembled

There are lots of technologies that have been developed in the pursuit of letting people see in three dimensions. The one people my age can remember from childhood are the red / blue tinted 3D glasses. These work by taking one image that you can focus on and splitting the color information between each eye. A similar technique is used in 3D films where polarization is used to split an image instead of color. Active Shutter 3D glasses also split a single image into information for each eye by rapidly alternating blacking out light from each eye at the same rate that the image on the screen changes. The Cardboard technique is a little older and doesn’t bother trying to overlay one image on another. On the plus side, you can get really good 3D imaging results without much technology to figure out (which means lower cost, etc). On the negative side, however, this technique can lead to eye strain because not every pair of eyes is the same distance apart. To illustrate, lets say that your eyes are 1cm closer together than the average pair of eyes that Cardboard was designed for. Then lets say that the simulated image is a ball floating in air straight ahead of you, so the simulated image for an average person would have the image of the object just slightly off center toward your nose so that both eyes settle on the image and your line of sight is where the object would be if it were actually there. To your slightly narrow-set eyes, the image would appear closer to right in front of your eyes, making the object seem further away and distorts the 3D effect. Don’t misunderstand, eye strain of this sort plagues every 3D viewing technique, but it can be more pronounced when the actual image is closer to your face.

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The Business-End of Cardboard

The head-tracking feature is a pretty exciting one, too. It works on the principle that in any cartesian coordinate system, movement can be described by 3 dimensions of translation and 3 dimensions of rotation. I’m guessing that the apps on the phone will not account for translation. I came to this conclusion from experience and also by imagining idiots like me holding the VR headset up to their faces while tripping over furniture. Using the information from the accelerometer to tell the phone which direction is down and the angular rate from the gyro (that’s how fast it’s turning), the phone can calculate about which direction you’re facing. There are apps that do this very well with very sophisticated integration and error correction algorithms and there are others that don’t do this well at all. One app that comes to mind will track your head if you move, but once you stop moving, the image slowly drifts back to dead center again. It’s possible that this was done deliberately to keep the viewer’s eyes up front, but I can only guess.

Obviously, I think this technology and implementation are awesome and I’d like to see more happen with it. Some things in particular are more stereoscopic videos on youtube and for NASA to convert it’s library of stereoscopic images from Mars to work on Cardboard. Perhaps the technology could even be extended to augmented reality.

That was my project day, how was yours?

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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.

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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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The ThrAxis – Our Scratch-Built CNC Mill

As it turns out, you CAN make a CNC machine on a shoestring budget! It just takes a lot of time, reading, effort, and… time.

Working the ThrAxis

Taking the ThrAxis for a Jog

The ThrAxis (Three-Axis) is a vertical milling machine made mostly from materials from hardware stores. The spindle is a Harbor Freight rotary tool and the motors and controllers are surplus and eBay finds. We made it during lots of late evenings using mostly handheld power tools and “garage precision”. It was a fun project for me to work on with my wife and it’s become a handy tool. I’ve found that it has accelerated my ability to realize my project ideas and has made it much easier to make things with the personal touch. We’ve made toys, art, and mechanisms and we have plans for much much more.

Silhouette Cutout Lion Archway
Cutting out the Silhouette of a Lion Archway Lion Archway Cutout

Why would you make a CNC machine in your shop? It seems like such a daunting job and what the heck would you do with it when you got it? These are the questions I heard when I brought up the ThrAxis to most people. They were right to question because it’s not an easy job. Since working on projects is what I do for fun, the doing and the why were a given for me, but I found it hard to explain. CNC machining allows you to make amazing things; things more precise, rapidly, numerous, and intricate than a person could make by hand. Of course you’re limited by a spinning tool and how far your machine can move, but it’s way more capable than a handsaw and a Dremel tool. My first inspiration was bloodying my fingers forever bending little 1/2″ long wires for RadioShack prototype circuit boards, then chemical etching circuit boards by hand (having only about a 10% success rate), and then spending $100+ on professionally-made circuit boards made me realize that there has to be a better way to get my ideas from breadboard to circuit.

First, there was the ‘buy a CNC machine online’ fiasco. Basically, I saved up a lot and found a few companies online who were selling CNC milling machines. I found one that was in my price range, but the lead time was months. BIG MISTAKE. And I had to pay the full amount up front. RED FLAG. I didn’t hear a peep for a while (eek!) and when I finally reached out, I got no response. I thought my money was safe because I used PayPal to send it. Wrong again! PayPal only guarantees purchases made on eBay. Eventually, I used the refund processes in PayPal to get my money back and got very very lucky, but my experience definitely left a bad taste in my mouth.

Then I started to think seriously about making one on my own. Mostly, though, I blame Make Magazine for my inspiration to do it myself. Since the first issue of my subscription, I’ve seen featured projects for dozens of gantry-style CNC router tables. Throw in the discovery of surplus electronics websites like all electronics and goldmine electronics and I was on a collision course. The final straw was finding the instructable article by Tom McGuire. We liked his design because the boom-style tool holder seemed more stable than the gantry-style CNC router projects we had seen (necessary for making circuit boards). It also has fewer moving parts than the gantry-style CNC routers which means fewer bearings and fewer opportunities for misalignment. The use of the inexpensive rotary tool instead of a router was also a big deal because it meant we could build something that would fit in our tiny workshop.  After a couple of coffeehouse design sessions with my wife, we had some plans and bought the parts to get it done.

I’d been toying with the idea of making a CNC mill for years, but to get this project up and running took about 4 months from drawing up plans to cutting out a part, $250, and a dozen stops at the hardware on the way home from work. Just like the reference instructable, the frame is made from black steel pipe, the stages are made from HDPE, and the screws are 1/4″-20 threaded rods. We added our own features and changed the size of the shapes around to suit our needs, though. We opted for some thinner, leaner materials in the interests of cutting costs. We also took some other liberties with the design, for example the use of 1/4″ fuel line as a motor coupler didn’t seem like a winner, so we used some 1/4″-20 threaded couplers half drilled out with set screws in the shaft section instead. My favorite feature is the bearings: they are actually skateboard wheel bearings. We got a box of 8 of them for $12!

Here’s a brief bill of materials of what we used:

  • 3/8″ HDPE sheet for all of the stages
  • 3/8″ architectural C-channel for the linear guides
  • 1/4″-20 threaded rod for the linear drive screws
  • 3x 1/4″-20 couplers for linear drive nuts
  • 3x 1/4″-20 couplers half-drilled out to 1/4″ with #6-32 set screw hole for motor coupler
  • 8x skateboard wheel bearings
  • lots of washers to level the stages
  • 2′ x 2′ sheet of 1″ MDF for a foundation
  • 3x 3.5A stepper drivers from AutomationDirect
  • Power supply for stepper drivers also from AutomationDirect
  • circuit breaker
  • logic level converter built around a 74LV125AN buffer
  • E-stop button
  • 6 limit switches
  • Shielded cable for stepper motors
  • 6′ of T-slotted track

Fortunately, there is so much material online regarding CNC milling and making CNC machines that we were able to get over almost all of the little roadblocks. We were able to assemble it using hand tools, a cordless drill, drill press, a level, and a roofer’s speed square. We had a few occasions to use some taps, too. We are using the TurboCNC software graciously provided to the community for free by DAK Engineering to interpret the g-code on a Windows 95 laptop (a dinosaur, to be sure) which sends the commands through the parallel port to a scratch-built voltage logic level converter to step it up from 3V output to 5V, then into the stepper driver cards. The reason we are using the Windows 95 computer is because we have it and the free TurboCNC software runs in DOS mode, which isn’t available on modern computers.

After we got it running, the first part I made was a raised ‘E’ logo that I use to mark my prototypes. That was my wife’s idea. It was a good test of the ThrAxis’s capabilities because it used rapid moves, drilling, full tool width cutting engagement, circular cutting operations, and excess material removal. The finished part wasn’t too complicated, but it had three different elevations, so that was an achievement. After that I was hooked and just wanted to crank out parts, so I started out doing cutouts of flat materials. I made a few fixture plates for a mobile robot I’m working on and made a few other parts for around the shop. My favorite is a fixture for a cellphone holder so I can rock out and charge my phone while I’m hard at work on the weekends. My wife and I have also done some cutouts of the half-lap rockets from last week’s post. Those are fun because you can make little changes to make the rockets unique and for the most part, the GD&T isn’t important with artistic cutouts. Right now, I’m working on cutting out circuit boards (my first goal of having a CNC machine) and the attempts are teaching me a lot about runout, backlash, tool condition, stage flatness, and feeds and speeds. So far, I’ve broken two tools, but I know why they broke and that makes the experience worth it. I’m also learning about the details about machine code: how the command structure changes with the software that generated it and how the interpreter software sends those commands to the machine. Just a bit of advice: complication goes up exponentially as the part size goes down, so be prepared. It cuts soft materials like wood, MDF, and expanded plastics really well, but I’ve been having problems with cutting solid plastics. I think we have a torque deficiency in the rotary tool, so I haven’t tried to cut solid aluminum or copper yet, but maybe some day.

ThrAxis Machining a demo part

Given that my wife and I didn’t have machine tools to manufacture precision parts before we built this, there’s nothing I would go back and do differently. Moving forward, however is a different story entirely. We’ve been making small modifications to the machine since we built it. So far, we’ve added screw cover bellows and a vacuum system to keep the dust down. I’d like to replace the rotary tool with a better spindle. The rotary tool doesn’t have a lot of torque and very little speed control, so some more power and the ability to regulate speed are key improvements to improving it’s cutting ability. I’d also like to improve the guides to improve position accuracy. I’m not sure yet if that means adding more bearings for the guides to ride on, changing the motor couplers, or replacing the nuts we use for moving the stage with a more rigid assembly, but there is room for improvement. I’d also like to figure out a better way to transfer programs to the Windows 95 laptop. Bear in mind, this is pre-USB and wi-fi, so there’s no simple way to do the file transfer.

That was my project day, how was yours?

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Growing projects one dimension at a time

What do Ikea, Captain EO, and CNC router tables have in common? They all use 2D materials to make 3D things and it’s easy for you to do, too. (even without any of those things)

Mini Rocket

Mini Half-Lap Rocket

There are a TON of things that people use every day made from flat materials… tables, cookie sheets, bookshelves, wooden Santa Clause puzzle kits, picture frames, and even this MDF rocket. Sure factories use automated power saws, die cutters, and tools that cost more than your house, but that’s only because those tools are required by manufacturers to keep their costs per item down. If you only have to make one of something, your technique doesn’t have to be so sophisticated. Even CNC machines and 3D printers can be overkill. The only tools you’ll need for some DIY projects are a sturdy work surface, a saw, and a drill.

There are many ways to use sheet material to make structures and they all use some combination of opposing forces to make the structure strong. One of the most common (and my favorite) is to use columns between plates to expand the flat dimension of your material. This does two things: First, it makes even a flexible plate more rigid (stronger) the same way an I-beam gets its strength from three relatively thin plates (in engineering terms, this increases the moment of inertia without increasing the weight). Secondly, it adds a lot of volume to what you are making without adding much weight. On a large scale, you could use PVC pipe, a few washers, threaded rod, and some nuts to make the columns. The opposing compression in the pipe and tension in the threaded rod make the column super strong, stable, and rigid.

Arduino with Standoffs

Standoffs are a perfect example of column-separated plates

Another joinery technique is actually the subject of this project day: the half-lap rocket. The idea here is to cut opposing grooves in material so they fit together like a puzzle. When the two pieces are joined together, the structure will be very strong because a force that would bend an unsupported thin plate in half is being opposed by the other plate not wanting to bend along its edge.

One of my favorite projects lately has been some small MDF rockets made out of two cutouts in 1/8″ thick material. The outline of each one is identical and the only difference is that one piece has a slot from the top to the middle and the other has a matching slot from the bottom to the middle. When you put the two pieces together, the rocket is free-standing and 3-dimensional. The best part is, you can make the same figure with some MDF and a coping saw, just follow these simple steps!

1) Draw the object you are going to cut out. Feel free to make anything you like. The guiding principle for the rockets was to make them symmetric with the half-laps made on the dividing line. If you want to use my design to make a rocket ship, print this PDF.

2) Cut out the shapes. Make sure the cutouts are as clean as possible. They will become a stencil in the next step.

3) Trace the stencils onto your material. Remember, the slots won’t work unless the material and the slots are both about 1/8in thick. If your material is a different size, adjust the slot width to match. Make sure to leave some room around the tracings so your cuts in the next steps won’t start right next to the finished cutout.

4) Use a coping saw to cut between the two tracings and cut away most of the excess material. The idea is not to start cutting on the lines of the tracings, but rather to leave room so your cuts aren’t starting right next to the cutout in the next steps.

5) Using a drill, drill a 1/8″ hole at the end of each of the two slots, this will make it easier to finish them. If you don’t have a drill available, you can use a back and forth method to clear the material from the end of the slot in step 7.

6) Make your detailed cuts by cutting lines from the edges of your material to the sharp inside corners. Remember, coping saws can cut contours just fine, but it won’t cut hard angles easily and could even break your blade. Make multiple cuts to take the excess material away in wedges or strips.

7) Now that the exterior of the tracing is gone, cut the grooves. If you have a piece of thick scrap with a straight edge, you can clamp it to your cutout with the edge right on the line of the groove so as you cut, it will make sure the blade doesn’t go too far astray if you lose your line.

8) With the two halves of the rockets done, you can sand the edges smooth, put them together with a little glue in between, and you’re done!

If you’d like to add some finishing touches, you can paint them with a crazy design or add some LEDs for a more retro high-tech effect.

Bonus project!

 IMG_2420

Coping Saw Guide made from 1/8″ aluminum bar

I find its best to use a cutting guide to improve the precision of my cuts and make life easier in general. You can make one with a long strip of scrap. Thick, rigid material is best. Mine is made from a scrap of aluminum plate. Cut a V in one end of the scrap at about a 60 degree angle and secure the other end to your work bench. As you cut, if you keep the saw blade close to the crook in the V, there will be more support on the material, so more of your energy will go into cutting and less into keeping the material flat on the edge of your bench, allowing you to control the direction of your cuts.

Using the techniques here, you can make a LOT of things from mini animals to project enclosures. The possibilities are as limitless as your imagination.

That was my project day, how was yours?

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Makers will have their Day

By Presidential proclamation, June 18, 2014 is the National Day of Making!


You can find details of todays first white house maker faire through the White House blog. (Thanks to Farzan for the nudge).

In honor of the day, go make something and share your project in the comments section below.

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Building memories with Dad

Happy Father’s Day (weekend)!

Some of my fondest project memories involve my dad. He gave me my first lessons in electricity, wood working, telecommunications, metallurgy, construction, and siege machinery. He showed me the right way to stain wood, cut plexiglass for model airplane propellers, and pick out the good lumber. I’m always thankful for the lessons I learned just by helping him work on his projects.

So take advantage of today and grab your sons and daughters and start a project with them. There are plenty of project ideas online that you could build with your kids. You would be surprised at how much that will develop them as people, teach them skills, and feel the joy of sharing the things you are interested in.

Here are a few suggestions to get you started:

Ripcord Rotor Chopper

Water Bottle Rocket

Wooden Tool Carrier

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