A quick survey online found some instructions on making your own or even buying pre-made ones. Ignoring all, I plunged ahead. After all, this is about learning, building, and probably screwing up, not just having a finished product.

I found a cheap, unopened cassette tape at a local surplus store, but it turned out to not have the screw-joined halves I thought it would. I was going to have to raid my old stash of tapes from the corner of the basement. I haven’t listened to a tape in at least a decade, don’t even have a tape player, and certainly don’t still have the old Yamaha multitrack recorder these were recorded with, but I still had a tough time sacrificing it. Why, there could be a heartfelt masterpiece on that tape that 22-year-old me recorded. Someday the archivists (or prison psychologists) will want to study it!

Oh well.  Onward!  I at least chose one without a label, on the theory that if I hadn’t thought it worthy of labeling back then, it couldn’t be that important. Now we’ll never know.

With tape in hand, I needed a flash drive. I had a few laying around, so after disassembling the tape to see just how much room there was inside, I spent an hour or so trying out different drives for fit. I wanted the tape to retain its original profile, but I wasn’t sure whether the USB drive should slide out, swivel on this axis or another, or just present a port that would require a separate cable. The drive that seemed most promising was a 2GB SanDisk Cruzer and its sliding action; it would require the least modification to the tape and would be the strongest.

The donor drive, in and out of its original housing.

On a side note, I’m amazed by the fact that I live in a world where it’s hard to find a cassette tape, but I’ve got multiple gigabyte+ storage options buried in my junk drawer.  I remember when these cassette tapes used to be the storage for my computer. Three cheers for progress!

With a 3/16″ end mill I milled the port for the USB connector to slide in and out of. Then, after measuring and re-measuring more times than I can count and mapping out the exact numbers of turns and even which direction to turn the handles on the mini-mill (I’ve only had it for a month, and this was my first project after getting it set up), I plunged the mill into the tape and started cutting the opening for the sliding mechanism. I put the opening on side B of the tape, so that side A would look stock while it was in the case. All the planning worked out well, because when I popped the tape out of the vise, the drive fit perfectly.

Unfortunately, the two halves of the cassette didn’t quite fit together. If the SanDisk folks had made their drive just the smallest fraction of an inch thinner, it would have slid right in for a perfect fit. I was going to have to thin the cassette shell.

The finish is a little rough, but it works. You can see the opening for the slider, the thinning of the case, and the notch that keeps the drive locked into place when it’s all the way out. With side B milled out, I tried to put the two halves of the cassette shell together again. No luck, and side B couldn’t stand to lose any more plastic, so I did the same thinning on side A.

A test fit found everything sliding easily when it was supposed to and locking down when required, so I moved on to the reels next.

As you can see in the photo, the take-up reel got in the way of the memory. I attacked it with the belt sander and ground it down just barely to the inside sprockets, then glued it into place (below). It would have been nice to retain the tape functionality, but it wasn’t to be.

The spool of tape on the other reel was a little bit too large and kept the memory assembly from being able to slide all the way back. I didn’t want to unspool too much and lose the full-tape look, so I experimented with the spare tape I got from the surplus store and put some superglue across half of the reel. The thin glue quickly soaked in and glued the layers of tape solid enough that I was able to cut it right through with an X-Acto knife without it unspooling. The cut was a little rough, but that could be cleaned up. More detrimental was that it would be obvious from looking at the little crusts of dried glue through the tape’s window that it wasn’t quite right. Maybe something useful can be done with this tape-solidifying knowledge later.

So after that I decided it might not be so bad after all to lose the 1/4 inch of tape needed for clearance. Finally, a part of the project my four-year-old could help with: “Take this end and pull until I say stop!”

When our fun was over with, I threaded the tape back around the rollers and through the guides.

I know there are some problems with the tape path in this picture. I realized and corrected after the photo.

At last, I put the two halves in place and screwed them together. I didn’t have any labels for the tape, so I trimmed down an address label and used that, then plugged it in to the computer and reformatted to use the name “Mix Tape” (what else could it be?).

The drive works well on my laptop and in the USB port on my desktop machine’s keyboard, but because of the weight and leverage, I don’t know how it would hold up being unsupported in a port higher up on a desktop machine.

If I'd labeled it when I was 16 it probably would have had more stars, spirals, and other doodles on it than today's version.

Side A looks just like a standard tape, so much so that if it’s still in the case you’ll only notice the USB on the side if you look closely. I’ve handed it to a couple of friends, saying “I’ve got some music I want to share,” only to have them laugh and complain they had nothing to play it on. They have to be told to take it out and flip it over.

And now I have to go make some for them. That’s the trouble with making cool stuff.

Required materials:

• Stormtrooper neckwarmer pattern, printed (49KB PDF)
• 3/4 yard of white fleece
• 1/4 yard (or less) of black fleece
• 1/4 yard (or less) of gray fleece
• 2 black buttons, approximately one inch diameter
• white thread
• black thread

Cut the white fleece into a rectangle 22″ wide by 20″ high. Fleece has more stretch in one direction than the other, so make the stretchy direction the width since it’ll need to fit around your big head.

Print out the pattern for the mouthpiece and the—whatever the other thing is. A little bit of research tells me that fans call it the “frown,” so let’s go with that, even though it looks more like a mustache to me. Cut them out of the paper and pin them onto their respective pieces of fleece, black for the mouthpiece and gray for the frown. Make sure that they both have the stretchiness in the width rather than the height. Cut each from the fleece.

Fold the white fleece in half the long way to make a 22″ x 10″ rectangle, with the right side out. To figure out which is the right side, stretch the bottom edge of the fleece and see which way it curls. It’ll curl toward the wrong side, which should be on the inside of your fold right now.  Now find the left-right center, either by folding it in half or by measuring 11″ to the middle. The frown will go at the top, near the fold.

Pin the frown into place (only through one layer of white fleece), then unfold the white fleece and carefully sew around the edge of the frown. Tie off the ends of the thread on the back side, which will eventually be inside the folded fleece.

Now pin the mouthpiece into place and sew as close as you can around its edges, then tie off the ends of the thread.

Sew straight lines down from each mouthpiece corner on the top to each corner on the bottom, illustrated by the dotted lines on the pattern. This is to give the mouthpiece some contours, just like a real Stormtrooper helmet.

The buttons should be sewn on even with the edges of the frown and about 1/3 of the way up the mouthpiece. See the pattern for placement. Line them up carefully—it’ll look goofy if they’re not even—and sew them on.

Fold the fabric in half the opposite way you did before, outside in, so you’ve got an 11″ wide x 20″ high rectangle. You should only see thread, not a mouthpiece and frown. Sew down the edge with white thread, about 1/4 from the edge. Backstitch or tie off the ends of the thread.

Now comes the tricky part, because if you get this wrong you’ll end up with everything going sideways on your neckwarmer. Lay flat the fleece tube you’ve created, still inside-out with the seam centered on the back. Fold each end upward toward the center so the seams meet.

And here’s a picture:

Starting about an inch from the seam, you’re going to sew each end to its matching point on the opposite end, leaving approximately a 1/2″ seam allowance. Take care that you don’t sew the tube shut. In the diagram I’ve illustrated this by coloring each section. Red is sewn to red, orange to orange, around to blue, then green, being sure to leave an inch before you get to the seam on the other side. Backstitch or tie off the thread ends.

Now you’re going to turn the whole thing right side out through the hole you left. Fleece is stretchy; it’ll fit. Roll everything around so the seam is on the bottom and the mouthpiece and frown are facing out. Close the hole you squeezed it through with a ladder stitch.

With white thread, sew through both layers of fleece from one corner of the frown down and around one button, across the bottom of the mouthpiece, around the other button, and back up to the other corner of the frown. This quilting (illustrated below in red) will give your Stormtrooper’s face a little bit more depth. You could do more quilting around the mouthpiece and buttons for additional detail, or add the rows of stripes along each side with embroidery floss. If your sewing machine has a stretch stitch, you could sew around the sides in order to approximate the tubes on the side of the helmet, but doing it without a stretch stitch will keep the neckwarmer from expanding when you pull it on and you may break the threads.

That’s it! Add a blaster and you’re ready to go.

Thanks for checking out this tutorial, but please don’t ask to buy the one I’ve made. It’s not for sale, and making any for sale would likely lead to a visit from George Lucas’ legal droids that I would rather not have. I do have other fun neckwarmers for sale, though, at www.stachewarmers.com.

The main body of it is a tube about sixteen inches long, tapering from around 2-3/4 inches at its widest in the middle to around an inch and a half at each end. Fold the fabric in half and cut an 8.5″ long piece to ensure each end tapers the same. Cut out one piece for the outer fabric and one for the the inner fabric. I used the core memory pattern on the outside and a solid blue on the inside. Put the two pieces together with their good sides facing each other, then stitch along the long edge (not the short!) with a 1/4″ seam allowance. Turn it right side out.

I wasn’t so good about taking pictures as I went, so I hope these scribbles can clarify things. Dimensions are all approximate; adjust them as you see fit for the look you’re after.

Make another tube to hold the elastic in back. I chose a bright red to match the wires in the memory pattern. When finished, this piece will be about an inch across and twelve inches long. Sew the long edges like you did with the main piece, then turn it right side out. Slide a 5″-6″ (depending on the size of your noggin) piece of elastic through and stitch one end at a time. With the elastic in it, all the extra fabric will scrunch up nicely to only a few inches long.

Roll each end of the main headband piece in so there’s a nice, clean edge. Slip one end of the elastic piece about half an inch into the main piece, then sew the two together. Sew back and forth a few times because this will have a lot of tension on it. Do the same on the other end.

When it’s all done, hopefully something like this emerges:

I also had an 8″x8″ sample piece of an upholstery-weight twill with the pattern printed. Eventually I’d like to make an iPod or Kindle case, but this sample wasn’t big enough for that. However, it was just the right size for a coin purse or iPod cover. This was my first project with a zipper, so I unlike with the headband I wasn’t going to go freestyle on this one. I found this well-illustrated tutorial from noodle-head.com, and after just a little cursing (“which of these is the F&$*# zipper foot?!”) I managed to put together the pouch below.

Read on for the story of how I went from the rough concept sketch above to a finished design printed by Spoonflower, an online service offering on-demand fabric printing.

The first order of business was getting a good image to base the pattern on. The one I’d taken at the museum wasn’t strong enough, so I turned to Google image search and found a photo of Univac memory that gave me a starting point.

The design started in Adobe Illustrator, where I set out the pattern of wires, then drew rings over the intersections. I used the 3D Extrude & Bevel tool to give the cores some depth and rotate them into the right alignment.

When they were done I moved over to Photoshop for the mind-numbing exercise of carefully erasing the wires where they had to pass through each core. Each of the four directions of wire needed two layers, with one for the segment that went into the front face of the core and one that came out of the back face of the core. I ended up with a PSD containing a dozen layers with names like Upper Diagonal Up, Upper Diagonal Down, Lower Horizontal, Core Highlight, & Core Shadow.

With that done came the work of testing the pattern itself to make sure it repeated well. To create a pattern in Photoshop, select the area you want repeated, then choose “Define Pattern…” from the “Edit” menu. Name the pattern and save it. Then open a new, larger document and choose “Fill…” from the “Edit” menu.

It turned out that I’d missed some pieces at the corner that didn’t show up until I repeated the pattern across the screen. After cleaning those up, I printed up some color copies at two different sizes and with different background colors, and stuck them on the fridge to glance at over the next few days.

I found that when I focused too hard on the pattern, sitting in front of it trying to decide what would look best, I couldn’t come to a decision. But when I stuck it up where it would catch my eye in passing, it was easier to make a judgement. This makes some sense because that passing glance is how it would be seen most often in a finished product. Through this process I realized that the larger pattern was the best.

Here’s the file I sent off:

That’s it.  Just those sixteen cores. They would be repeated across and down the fabric automatically.

And here’s the 8×8 inch sample that came back six days later:

Pretty cool! And only five bucks!  I was psyched, and spent a few days folding it into different shapes — neckties, headbands, bags — to imagine how it would look in a finished design. Eventually I came to realize that the design was too literal. The highlights and shading detracted from it by taking it out of the realm of pattern and into that of a more concrete picture.

For my second stab at it, I used the same basic design but went with a simplified two-color core: one color for the face color and for the edge. The wires became thicker and solid red, and all of the elements had a white border applied to set them off from the background.

Now that pops!

I was confident enough in the pattern that I ordered a larger quarter-yard piece of sateen for something like a necktie and an 8″x8″ sample of a heavyweight upholstery fabric that I planned to eventually order more of to use in an iPad or Kindle case.

The fabric arrived about a week later, but the sateen had some printing problems that caused the bottom half of it to be blurry. The photo below has the good half folded over on top of the bad half. It’s especially evident in the white lines (or lack thereof) bordering the red.

I emailed SpoonFlower and to their credit they were quick to respond and reprinted it without any hassle. They even sent the replacement fabric via FedEx 2nd day air, which wasn’t necessary but was much appreciated.

Stick around for some photos of a couple of finished pieces I made. I’ll try to post those in the next few days.

If you want to order this fabric and make something for yourself, you can do so here through SpoonFlower. I’m currently adding a few background color variations, but have to order test swatches before I can sell those. If you order some and make something, please share a picture or link.

My initial concept was simple: a seven segment LED display so it could be read in the dark,  a rotary switch in the middle to choose the value to operate with, and big buttons for adding and subtracting.  Green makes the number get larger and red makes the number get smaller.

Below is the finished product. Click the “Continue Reading” link under the picture for details about the process of building and programming. I didn’t take a lot of photos through the build process because there wasn’t much to see, so I’ll illustrate relevant parts of the writeup with photos of the finished counting box. Also, please be aware that this is meant more as a documentation of my build process and the things I learned, rather than as a step-by-step how-to guide to make your own. I hope you’re still able to learn something or be inspired.

The Circuit

The electronics were first, since the size of the case would depend on the size of the finished electronics. I ordered these 4-digit seven-segment displays and this 10-position rotary switch from Mouser, and these video game buttons from Sparkfun. It would all be driven by a standalone ATMega 328 on a perf board. I wanted a big display, lots of numbers, and sturdy buttons. Miniaturization was not on the priority list.

The basic circuit was pretty easy to breadboard and program, but oh that confusion the first time I  set the dial to 1 and pushed the increment button, only to watch the display whizz right up into the two-hundreds. Not so nice to meet you, switch bounch.

If you don’t know—and I didn’t—switch bounce is the electronic noise or chatter on the millisecond level as a switch’s contacts open or close. What seems like one button push to us can be read by a microprocessor as dozens, hundreds, or more. Days of research followed on the best way to deal with it (a function known as debouncing): hardware or software, SR latch or RC? My head was swimming.

Fortuitously, the buttons I ordered happened to be double-throw switches, allowing me a fairly simple debounce solution in hardware with two NAND gates for each switch, using a 74HC00 integrated circuit with four such gates. The debouncing explanation at robotroom.com guided me well through the process. I still can’t completely wrap my head around it, but it works.

The astute among you may have noticed, if you clicked the link above, that the rotary switch was complement coded. I had no idea there was such a thing, but the end result is that that “on” should be measured as “off” and “off” as “on” when processing the output. An output of 1110, instead of being read as decimal value 14, was really 1. It was a learning experience as I worked around it in the code, and something else to watch for next time I order parts.

I also needed a way to store the current value of the display. One of my goals was to not have the display reset whenever the power was turned off, because this shortcoming of calculators has led to a few tears in the number-loving boy, and I could do better. This should be an easy job for the ATMega’s internal EEPROM, but when I started looking it was only rated for 100,000 write cycles. With a display that could go up to 99,999,999, that didn’t seem good. Instead I found the 24LC256 2-wire serial EEPROM, with 1,000,000 write cycles.

The display is driven by a MAX7219 chip, which can drive 64 LEDs or 8 seven-segment digits with only 3 output pins on the ATMega. Interfacing with this was easy, with the only difficulty coming from keeping track of which wire was which when linking to the LEDs. Counting up to 99,999,999 might take a while, but it’s good to have goals, right?  The real reason I went that high was only because I didn’t want to wire up individual LED displays to make a seven digit display, and two 4-digit displays was a good fit for the box size I was working toward. Design-wise, the edge of the display lines up with the vertical centerline of each button, and the distance between the buttons is dictated by the size of the circuit board that fits between them.

I put it all together on a Radio Shack perf board, which later had to be trimmed to fit the finished box.  The LED displays are on another larger perf board connected by ribbon cable to the main board. For the first ribbon cable I used an old hard drive cable, but by the time I did the second I’d picked up some rainbow colored ribbon cable. I didn’t feel like re-doing the first so I left it gray. The display perf board also needed some material removed where the buttons went, and the roller on the belt sander gave it just the right radius.

One big change right at the end was that my original concept had two sets of three AA batteries in series, feeding in parallel into a 5v step-up circuit. After putting together the wooden case and playing with it, I realized what a pain it was going to be to swap out and charge all those batteries, so instead I ordered a 3.7V 6600mAh (overkill, I’m sure, but better overpowered than underpowered, right?) lithium ion battery pack from Adafruit and a Li-Ion USB charger to go with it. Those feed into the step-up circuit, which provides the 5V the system needs.

The picture below shows the finished circuit right before I mounted it into the box.

The Software

I don’t want to fill up this post with all almost-500 lines of it, but you can take a look at the code here. Between my comments in the code and my discussion below, you might be able to make some sense of it.

There are 3 main things the code needed to do: display numbers, handle button pushes and incrementing/decrementing a variable, and finally storing that variable to memory.

The number display is handled by the LedControl library driving the MAX7219. One challenge I had was figuring out how to split the number variable into its component digits. The modulo operator provided the answer, by successively finding the remainder of the value divided by 10 and storing it to an array, then dividing the number by 10 to move on to the next digit. Let’s take the integer 982, for example. 982 mod 10 (in other words, the remainder of 982/10) is 2. That means 2 will be the digit in the ones place. Now 982/10 = 98 (it’s an integer, so there’s no .2). 98 mod 2 = 8. So 8 will be the digit in the tens place. 98/10 = 9. Since that’s the last one, we don’t need to find the remainder.

Button pushes come through as interrupts, which do pretty much what it sounds like they would—they interrupt any other actions taking place in the program when a condition changes, in this case the status of the button. The other alternative is to constantly poll the button to see if it’s being pressed, but this is inefficient compared to essentially asking the button to let you know when it’s being pressed.

The functions that handle the interrupts first check to see which mode the system is in, then acts accordingly. There are three basic modes: NORMAL mode (mode value 0), DELETE mode (mode value -1), and STATS mode (mode values 1-4). If the system is in normal mode, the interrupt handler calls a function to read the rotary switch and decode it, reset the idle timer, and then it adds or subtracts the value indicated by the switch. If it’s in DELETE mode, pushing the decrement button confirms the delete and resets the counter to zero, while pushing the increment button cancels out of DELETE mode into NORMAL mode. In STATS mode, pushing the increment button display the next statistic.

Memory is handled by the I2C example from Arduino Playground, with unnecessary stuff cleared out. In every loop, the program compares the current value of the variable to the value of the variable on the previous loop. If they’re different it stores the new value to memory.

The statistics feature I mentioned before stores the highest value reached, the lowest value reached, and the total number of button pushes for each button. This secret stats mode can be accessed by setting the rotary switch value to 3 and holding down the green button on startup. The setup() function checks for that condition and if it exists, sets the “mode” variable to 1. The loop that displays values sees this and displays the appropriate statistic. With each button push after that the increment() function advances the “mode” variable, and the display updates accordingly. This should make for some fun revelations in a few months or years.

My original circuit plan had a zero-switch reachable with a paperclip through a hole in the case, so it wouldn’t be accidentally bumped. I wasn’t quite sure where the circuit was going to fit into the case so I decided to drill it myself rather than having it laser-cut. It’s a good thing I took that route because after writing the stats code I decided to handle zeroing numbers the same way in software, not hardware. So, if you the set the rotary switch to 8 & hold down the red button on startup, it’ll ask you to confirm you really want to reset, then take the current value back to zero. I haven’t told my son about this yet; it’s more fun to watch him work on his subtraction when he wants to get back down to zero. “If you have 16, what’s the fastest way to get to zero? 10 and 6? How else could you do it?”

To save a little bit of power, the ATMega and the LED go to sleep if no buttons are pushed for one minute. Pushing either button will wake it again without incrementing or decrementing, then return control back to the regular interrupts.

I don’t feel like I optimized the code as much as I could have, but then again there’s not a lot of point to doing so other than geek pride. It works, and that’s what matters.

Construction

I designed the case in Adobe Illustrator and planned to have it laser cut from bamboo by Ponoko. I’ve used their service before, but never for anything like this that had to fit together so precisely. To make sure it would all fit, I printed the plans, spray-mounted them onto 1/4″ foam core, then cut it out with an X-Acto blade and assembled it.  1/4″ isn’t an exact match for the .264″ bamboo, but it was close enough to tell that I hadn’t made any egregious errors like trying to fit two slots together, or two tabs. Not only did the mockup fit together, but everything fit into it.

Right before I sent my original plans off for cutting, I had a feeling there had to be some easier way to make the joints, and I found a great online utility called BoxMaker to generate a plan with all of the appropriate dimensions for finger joints on a box. Enter the outer width, depth, and height, the thickness of the material, and the kerf width, and out comes a PDF. I made a few minor tweaks to the spacing (for symmetry between left and right sides), placed the elements like the window cutout and button holes, and uploaded it to Ponoko. Here’s what I sent:

And two weeks later, here’s what arrived:

It was beautiful, but to my dismay, the pieces didn’t fit together. I’d specified too wide of a kerf, and in compensating for that the BoxMaker program adjusted the widths of the notches to close up gaps that didn’t exist. The notches were now too tight! It was nothing a little time with some sandpaper couldn’t fix, though, and with my son’s birthday rapidly approaching I didn’t have time to make edits and place a new order. It also turned out that the wood was slightly thicker than specified, so the tabs didn’t reach all the way through the corners. This shortcoming became almost invisible after some careful rounding of the corners to soften them up.

Once the box was glued together, it was time to cut some channels for wires to get from the front of the display board to the back. A router bit chucked into the drill press and plunged repeatedly to a depth stop took care of this. As tempting as it may be, don’t try to use the drill press as a router or milling machine because the bearings aren’t meant for force to be applied laterally. The rotary switch required that some relief be drilled into the wood, otherwise the nut holding it on couldn’t reach the threads. I did this with a Forstner bit in the drill press.

The red acrylic window covering the LEDs was also laser cut by Ponoko. Since I had an entire  7×7″ piece and the window was only about 1×5″, I put six different versions on, each sized a few hundredths differently.  If I’d simply used the same shape I used to cut the window out of the bamboo, the width of the kerf would make it loose. I was hoping for a tight fit that wouldn’t require any glue, and one of the sizes (I can’t remember which) was just right.

In another departure from my original plans (it happens a lot), I decided I wanted the back to be removable in case I had to pull something out for repair. There was no way I could get it all out and back in through the battery door like I originally thought I would, so I glued in some corner pieces to screw the back board to rather than gluing it as I did the other edges.

For durability, I used a gloss polyurethane to finish the wood and give it a warm, amber glow.

The final nerve-wracking test… would it be possible to fit everything in?

It was, but just barely!

To hold everything in place I cut and bent an aluminum sheet to use as a shelf, with the battery and voltage converter velcroed onto the front side and the circuit on the back. I drilled and tapped holes into the aluminum to mount the circuit, and of course managed to mangle the threads on one of the holes. Since it wouldn’t be seen, I super-glued a nut on the front side for the bolt to thread into. Adapt and overcome!

The last minute change in power sources also let me do something I’m especially grateful for, and that was to put the circuit facing outward where the AA batteries would have been, allowing the door on the back to serve as a little window to peek at the circuit. My son loves the Snap Circuits kit we share, and one of the first things he did after I gave him the counting box was to open the back and squeal “That’s a capacitor!  And that’s a resistor!” Oh, how my nerd heart leapt with joy!

To keep any fingers from pulling out fragile wires, I covered it with a piece of plexi cut to size on the band saw and smoothed on a disc sander, held off the board by standoffs that were cut down to just above the height of the mounted ICs. A few notches had to be made in the plexi for the USB charging port and its screws, but the belt sander made quick work of those.

The door on the back, originally meant to provide access to the batteries, is held on by 3mm neodymium magnets epoxied into holes drilled into the door panel and the frame. To ensure that the magnets on the door were aligned with the magnets on the door frame, I drilled guide holes through a spare piece of wood and used that as a template. The magnets are strong enough to keep the door on through regular use, but they give when pried open by fingers in the half-moon cutouts.

One last charging session, closely watched  to be sure nothing burst into flames, and at long last (four months since my first parts order), the counting box was done.  After all the work it was nearly impossible not to play with it myself, but I didn’t want to affect the stats it was primed to store.

The project was a lot of work over a lot of late nights, and pushed me to learn things I didn’t know about electronics, coding, and woodworking. Yeah, it’s just a silly box with some buttons, but my payoff for all of it is evident below. Somebody is pretty excited that they got all the way up to 1060.

But anyway, on to the repair…

The C1 piece, a .02μF capacitor, broke off at one of the legs. This is understandable, since the capacitor sticks out to be bent and squished accidentally by clumsy fingers.

If you look closely, you can see the broken right leg.

You can order replacement parts, but the shipping cost was prohibitive. Time to crack the case and peek inside! A fingernail and a small flat screwdriver (the size you might use to tighten screws on your glasses) popped the part open at the tabs without too much trouble, but be careful because if you crack the plastic that’s going to be a lot harder to repair than a wire inside.

Looks simple enough.

The local Radio Shack didn’t have any .02μF capacitors, but they did have .022μF. We had circuits to build right away, and it should be close enough for everything in the kit. If I feel like getting it exactly right later I’ll add a .02μF to the parts order for my next project.

Close enough.

The leads desolder easily, but be sure you don’t keep the heat on too long or you might melt the plastic directly underneath. Put the new part in through the holes in the case, bend the leads, then trim them to fit the tabs. The tabs don’t have any holes for the leads to go through, so just hold the lead onto the existing solder and heat it up. When it was done, the bottom half of the case clipped right on and we were back in business.

All fixed up and good as new.

]]> http://www.hahabird.com/2011/08/snap-circuits-repair/feed/ 2 http://www.hahabird.com/2011/07/screen-printing-press/ http://www.hahabird.com/2011/07/screen-printing-press/#comments Thu, 14 Jul 2011 18:55:56 +0000 Nathan http://www.hahabird.com/?p=541

After doing some freezer paper printing* on a shirt for my son, I wanted to do some more intricate designs and maybe even sell some of them, but didn’t want to spend a lot of money buying a press. So what do I do instead? Spend a lot of money building a press!  Click the “continue reading” link for some details on the construction of my homemade screen printing press.

*cut a stencil in some freezer paper, iron it onto a shirt, dab on ink, pull up the stencil, set the ink with an iron.

Let’s start off with a couple of exploded views of the whole thing—minus elements like screws, bolts, and hinges—so you can see how it all fits together, then I’ll go into details on each component. Keep in mind that I made these drawings after I made the press. There weren’t any plans; the whole thing was put together by trial and error after reviewing a handful plans found online for ideas. And my goal in posting this isn’t to give anyone a clear set of “buy this, cut here, do this” plans, but to show how I made mine and to share what worked and what didn’t.

The frame is made from a four-foot length of 3×3 laminated wood. A dado is cut into each leg for the arm base piece to rest in, then they’re glued and screwed together.

Plans I found online used wood instead of aluminum for the platen arm, but I opted for the lighter weight and stability of the aluminum. I haven’t found a 2×4 yet that wouldn’t warp and twist if I even looked at it. I rounded the end of the aluminum arm on the band saw then smoothed it out on a belt sander so it wouldn’t snag the shirts being pulled over it. Four countersunk holes were drilled to fasten it to the wooden arm base with wood screws.

The screen bracket is made with c-clamps JB-Welded to ten inches of 1.5″ aluminum angle, which is then screwed into two 1×4 pieces of oak I laminated together.

On my first try at this sub-assembly, I cut the bottom half of the clamps off and JB-Welded them onto the vertical part of the angle with the thought that it would look cleaner and keep the bottom of the clamps from interfering with the platen when it was moved all the way back. What I didn’t know then, but do now, is that JB Weld has the shear strength of a toilet paper spitball on the bathroom wall. With the slightest pressure on the clamps, they popped right off. Whoops, off to buy a new set of clamps.

The hinge is a heavy duty door hinge bolted (more details on that soon) to a piece of 1×6 oak. That piece is screwed to the foot/arm unit.

The press has an adjustable spring system to lift the screen and hold it up while you’re changing shirts. The aluminum angle slides back and forth in a channel to adjust the tension, and is then tightened with bolts. The eye bolt holding the spring can be threaded in or out to adjust the vertical position of the spring and therefore how much down force it exerts. If you don’t have access to a milling machine to make a slot for adjustment, you could come close to the same functionality by drilling some equally spaced holes.

One of my goals in this project was to make as much adjustable as I could, since I really don’t know what I’m doing and have no idea what strength of spring would be best, or at what angle one piece or another would work. Figuring out how to make these adjustments is what took the most time in the project (learning to use a milling machine to cut the slot here, for example), but the alternative would probably be to make three or four before I found my ideal.

Moving around to the back of the press, you can see slots routed into the hinge support piece. These allow vertical adjustment for the off contact distance by letting the hinge slide up and down. There’s enough wiggle room to adjust for some tilt, too.

In another learning experience, I think I made three of this back piece before I got it right. For the first, I drilled a hole then cut a slot with a scroll saw. It wasn’t as smooth as I’d like, so in my second attempt I remembered the router. In that one, however, I had trouble with my router fence moving and the slots veering off path. The third screw-up was because I was frustrated by the second and didn’t measure correctly. When I put it away for the night and came back later, everything worked out.

The other end of the spring attaches to an eye bolt screwed into a threaded insert. The removable link makes it possible to detach the spring so that tension can be taken off while the press is being stored. The threaded insert allows the bolt to rotate and maintain alignment with the spring. I also used threaded inserts on the bolts holding the sliding aluminum angle.

A chain with an s-hook on the end attaches to the shaft of the eye bolt and keeps the springs from pulling the screen arm too far back and dumping the ink and squeegee when putting a new shirt on the platen. In a case of project evolution springing from hardware store browsing, my original plan was to use 1/16-inch steel cable with loops crimped into the ends, but while I was waiting for a store employee to arrive to cut the cable length I needed, I saw the chain and realized its potential for adjustment versus the cable and its fixed length. To change the length of the chain and thus the angle of the raised arm, simply unscrew the bottom end from the threaded insert and put the bolt through a different link on the chain.

To make a stop for the arm, I drilled a hole through the aluminum arm and into the wooden base. A flange nut (because the flange of the nut has more surface area for attachment) JB-Welded over that hole provides threads for an elevator bolt to screw in and out and adjust the stop height. I didn’t even know what elevator bolts were before this project, but I discovered them while wandering through the hardware store looking for parts to use (or misuse).

The platen was cut from a piece of MDF. I couldn’t find a small enough sheet of laminate for the top and didn’t want to pay for an entire counter’s worth, but I did have some coated hardboard from a dry-erase project. I cemented that to the top of the MDF, cut it to shape on the band saw, then rounded the edges with a router. The hardboard makes the whole platen thicker than it would be with laminate, but that’s what the hinge height adjustment mechanism is for!

I made the platen bracket from two small pieces of 1.5″ aluminum angle — the same stock that makes up the clamp for the screen frame. Each is screwed into the bottom of the platen with extra care taken that the screws wouldn’t poke through the top. Holes drilled on the vertical half of the angle pass threaded rods through, which then have wing nuts attached. Tightening the nuts clamps the platen to the arm, and loosening the nuts allows you to slide into the position you want.

Finally, here you can see the entire assembly minus the platen and screen frame. The 1×12 base I attached it to is sized to fit just right across this table, then be clamped down for extra stability.

Primer and a can of red spray paint finished the whole thing off, covering all the patches and wood putty repairs of mis-drilled holes and errant cuts.

Now to build an exposure unit for the screens, then figure out how to actually print. I’ve got a feeling this hardware was the easy part.

The nostalgia was thick, with phrases like “I had that!” (Apple ][ and countless games) or "I so wanted one of those!" (Tomy Omnibot 2000) leaving my lips countless times.

But more than the sights and the sounds, what really hit me was the smell. The scent of some of those old computers instantly took me back to hours spent as a child digging through my mom's old camera equipment. Same smell in both cases. I don't know what it is—something in the finish, the circuit boards, the wire insulation, maybe the tiniest hint of mildew? If someone could distill that smell, I'd spritz it on the DSLRs I've got now in order to make them smell like real cameras should. Hell, I'd wear it myself.

I tried using small plastic envelopes in a recipe organizing box, and while it was nice being able to see them when an envelope was out on the desk, the envelopes were too floppy and it was impossible to flip through and find what I was after.

Then I remembered an unused two-drawer card file tucked away at my parents’ house that would be ideal. A2 envelopes were a perfect fit, and there was a sliding backstop in each drawer to keep it all packed tight.

Being a newbie to this electronics thing, I hadn’t yet memorized the resistor color codes, so I decided to print a color guide on each envelope along with the numeric value. The funny thing is that by making all of the envelopes in InDesign I’ve gotten pretty good at the color code system. I think they’ll still serve well as a check when I’m putting resistors back after a prototyping session.

The other night, with the envelopes all printed, I huddled over the piles and started sorting. First lesson learned: good light is a must. Under my lamp, red looked the same as orange looked the same as yellow. Brown and black? No difference between them! Eventually, with a few illuminations from a super-bright flashlight and a few particularly troublesome ones set aside for the morning, I got everything in its place and filed away.

Here’s the finished system. The resistors only take up about half of one drawer. What should I keep in the second drawer?

But I found out today in a big way when a Christmas package meant for Australia was returned for having an insufficient address. That’s about as far as anything could be sent, and then doubled for the return trip. It was shipped on the tenth of December, and marked “Return to Sender” on January 5. I’m not sure when it arrived down under or how long it was kept, but it only got back to me here today. That’s over three months on the road — a far more rigorous test than I could have devised!

It's pretty smooshed up. Good thing there's only fabric inside.

The internal wrap of tissue paper.

The neckwarmer just as it was pulled from the package.

Smoothed out by hand and good as new!