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Archive for the 'Macintosh Floppy Emu' Category

Acrylic, Wood, Hardboard, Oh My!

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The revision 4 Floppy Emu cases are here, and they look great! Clear and black acrylic in different layouts, birch plywood, and chocolate-colored hardboard. I’m having too much fun putting these together. The purpose of revision 4 was to test a few layout tweaks and a sampling of different materials, so I could decide which one to get manufactured in larger quantities. The layout changes are probably the most important, but first let’s talk about materials.

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First is a birch plywood. It’s actually just a thin birch veneer over some kind of filler layer, but it still looks very nice. You can see the veneer layers when you look at the board edge-on, and the edges are quite dark in color compared to the face of the board. This gives the case a high-contrast look. The engraved logo and text came out well, although they probably could have been a bit darker. The areas of the the board near the holes and corners are baked a darker shade of brown from the heat of the laser. The white case screws look decent with the light birch, though it’s not the best match. Overall the plywood case came out well, but I can’t say it’s my favorite.

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Second up is hardboard, which is just a higher-density version of the ubiquitous MDF fiberboard. You might think fiberboard is icky, but this case came out great and is easily my favorite. The faces are a dark chocolate brown color, while the edges are near black, and the combination looks nice together. The black case screws accent it nicely too. The engraved logo and text are clearly visible, yet still understated. The quality of the engraving is also extremely sharp and crisp. There’s no darkening of the board near holes and corners, like occurred with the plywood. The one big drawback of hardboard is that it requires more than twice as much laser time to cut than the other materials do, which increases its cost. If I sold a hardboard case, it would have to be for $4 or so more than a case made from acrylic or plywood.

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Black acrylic came out well too, and as expected it’s very similar to the previous cases I did in clear acrylic. I’m not in love with it, though. It’s very glossy, and it shows every fingerprint and smudge. The engraving is pretty good, but it’s like matte gray set against shiny black, and is difficult to see from some angles. Maybe it’s good… I can’t decide.

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The new clear acrylic case is almost identical to the old one, except I’ve increased the sizes of the finger joints from 4 mm (as shown on the black case above) to 18 mm. This gives the edges a much less busy look, and helps the pieces fit together more easily. Clear acrylic shows fingerprints too, though not as much as black. And everybody likes clear, right?

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I don’t have photos of the layout changes, but they’ll help save manufacturing dollars and assembly headaches. Believe it or not, going from 4 mm to 18 mm finger joints cuts almost $1 off the cost of the case. Fewer direction changes for the laser as it’s cutting means it can finish the job quicker. I also eliminated the two extra pieces I’d been using to accommodate boards with a built-in floppy connector, and instead there’s now a punch-out section on two of the boards that can be removed if necessary, opening a space for the connector. I tested the punch-outs in acrylic and they worked well – didn’t break loose accidentally, but could be broken off using only finger pressure when needed. I didn’t think to include punch-outs in the two wooden cases, but hopefully they’ll work equally well there.

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I also made several tiny size adjustments to help make the “swords” for the LEDs and buttons fit just right. And I didn’t quite get it perfect, but now I think I have the dimensions I need to nail it next time. The buttons have tiny nubs on them to help prevent them from slipping back through the top plate while you’re assembling the case. This worked pretty well, but wasn’t 100% reliable. I suspect it will still be necessary to use the tape trick during assembly that I described last time. Hopefully people won’t mind that too much.

Armed with all this information, I think I’m about ready to do a larger manufacturing run of at least a few dozen cases. Given what I saw from these, I’ll probably make the majority of them clear acrylic, and maybe make a few hardboard ones I’ll sell for a couple dollars more as “premium cases” or similar. Thanks to everyone who wrote in with their preferences and requests. Check back in about 10 days and I hope to have a stock of new cases ready to go!

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Designing a Laser-Cut Enclosure

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An official laser-cut case for Floppy Emu has finally arrived! It took a lot of prototyping and fiddling with tiny parts, but I hope you’ll agree the result was worth it. The case is only 6mm larger than the board itself, accommodates boards with the extension floppy connector or the built-in connector, and features light pipes to channel the LED’s to the outside of the case. The whole thing is cut from a single sheet of 3mm acrylic, and assembles like a 3D jigsaw puzzle.

I hope to offer these cases for sale soon, but I need help determining how many to make and in what colors. If you might be interested in a case, drop me an email or leave a comment below, and mention your color preference. Cases will probably be $19, and the color will be either clear or black.

 
Case Design

I was surprised how challenging it was to make a “simple box” case. My first plan was to design a 3D printed case, but I quickly abandoned that idea once I realized how expensive it would be. 3D printing is an impressive technology, but home 3D printers don’t really have the necessary reliability or speed for consistent manufacturing, and the material cost is significant. Online 3D printing services like Shapeways are another option, but they’re even more expensive. I also doubted I had the necessary 3D modeling skills to design a workable 3D case, so the idea never got very far.

The best alternative seemed to be a laser cut case, constructed of multiple flat pieces assembled into a box shape. Adafruit’s laser-cut enclosure design tutorial was a big help, as was the web-based design tool MakerCase. Before I knew it, I’d designed a basic six-sided box of the proper dimensions, with finger joints at the edges to hold it together. But would it work? Designing a case using finger joints this way requires compensating for the kerf – the thickness of the laser cut. Assume a zero sized kerf, and the box won’t hold together. A 5mm wide tab will end up closer to 4.8mm wide after cutting, while a 5mm wide slot will end up closer to 5.2mm, and the tabs will sit loose in the slots. To compensate, the tabs in the design file should be slightly wider than the desired finished size, and the slots slightly narrower, but not too much. Overestimate the kerf, and the finished tabs will end up wider than the slots, preventing the parts from fitting together at all.

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Next I added holes for case screws, the SD card slot, and the extension cable. Easy enough. But what about the buttons? Floppy Emu has four pushbuttons that are needed to operate it, so I couldn’t just seal them up inside the case. I could have cut a big finger-sized hole in the case lid above each button, so you could reach in and press it, but that seemed ugly and awkward. I could also have left the area above the buttons entirely uncovered, but that seemed even less appealing. If I were designing a product that was *always* in a case, I could have switched to a different type of push button with a long plunger that extended outside the case. But I’m not, and that would be goofy for everyone using a Floppy Emu without a case.

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The Stick

I finally concluded the only decent solution was to use some kind of stick to poke through a small hole in the top cover, and press the push button inside the case. This proved to be tricky to get right. If the stick were just a straight shaft, it would fall out if the case were turned upside down. And there was no positive force holding the bottom end of the stick onto the push button. It might wobble around or even slide off the button entirely, causing the whole stick to fall down inside the case. My solution was to add a crossbar to the stick to prevent it from falling out, turning the stick into a sword, and hoping that a tight fit between the sword and the hole would prevent it from sliding around. The light tubes used the same sword design, but modified in size to fit on top of an LED instead of a button. Voila! A finished design.

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I sent the design file off to Ponoko for manufacturing, and about a week later I received the laser cut parts in the mail. With eager anticipation I separated the parts, fit them together, and bzzzzt! I had overestimated the kerf, and the parts didn’t fit together at all. Total failure. I went back to the design file, reduced the kerf estimate by half and made a few other mods, and sent revision 2 off to Ponoko. Another week passed. Finally I got the new parts, and it worked! Sort of.

The rev 2 case fit together, and the Floppy Emu board fit inside of it, so that much was looking good. But the swords had big-time slippage problems. They were too loose, and were constantly wobbling around or slipping down inside the case. For revision 3, I made the swords a bit thicker relative to the holes, so they’d fit more tightly and have less room to wobble. I also added “feet” to the swords, to help keep them centered on the buttons and LEDs.

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Another week went by, and when the rev 3 case parts arrived, everything looked pretty good. The button swords still wobbled a bit, but not far enough to cause problems or fall off the button. The LED swords were more problematic, and sometimes wobbled off the LED’s centers, but generally stayed close enough to continue working as light pipes. Before offering these cases for sale I’ll probably do a rev 4 design to tighten everything up a little more, but rev 3 is definitely useable. Hooray!

Rev 3 also includes two alternate versions of the base and left side pieces: one for boards with a built-in floppy connector, and one for boards using the extension connector. That makes eight total side pieces, of which you’ll use six.

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Sword Assembly

The only aspect of the design I’m not thrilled with is handling of the swords during assembly. How do you get those little buggers in there and aligned correctly, before you put the top on the case? You can’t just balance the swords on the buttons and then lower the top plate onto them – the swords won’t balance by themselves. One option is to assemble everything upside down: put the top plate upside-down on the table, then place the swords into the holes in the top plate, and finally lower the inverted Floppy Emu board onto the whole assembly. That works, but it’s pretty awkward.

The best solution I’ve found is to do assembly right-side up, and use tape to temporarily hold the swords in the top plate. You assemble the bottom and side pieces normally, and place the Floppy Emu board inside. Then you loosely cover all the top plate holes with tape, and push the swords up from underneath until their top surfaces touch the tape. Now you’ll be holding a top plate with all the swords dangling down under it. Finally, you lower this whole package onto the rest of the assembly, add the case screws, and then remove the tape. It’s not the most elegant system, but it works.

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Colors

I originally planned to design the case in black, to give the final product a sleek iPhone-style appearance. But when I did a prototype in clear acrylic, my wife loved it and predicted it would be much more popular than black. One big advantage of a clear case is that it won’t need light pipes at all, since you can see the LEDs inside. The material is also a bit cheaper. But the etching on a clear case is difficult to see from some angles, and the final result with its exposed internals looks more like a science fair project than a professional product. What do you think? Which would you prefer?

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LEGO Case for Floppy Emu

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Chris Siegle has designed an amazing Floppy Emu case made entirely out of LEGO bricks! The case features LED “light tubes” and working buttons. Step-by-step build instructions are here. Thanks Chris!

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Floppy Emu “Scratch and Dent” Sale

Sometimes a Floppy Emu board fails one of my functional tests, and I can’t find the cause of the problem. I have several boards that appear to work fine for 400K and 800K disk emulation (tested on a Mac Plus and Mac 512K), but that don’t work reliably for 1.4MB disk emulation on newer Macs. Instead of throwing these in the trash, I’ve decided to sell the “scratch and dent” boards for $15.

If you’ve got a Mac 512K, Plus, or older Mac SE that only supports 400K and 800K disks, one of these boards might work well for you. Because the boards failed some of the functional tests, there’s definitely a problem with them, so keep that in mind when deciding between these and the regular Floppy Emu boards. Scratch and dent boards are warranted for 400K and 800K operation for 30 days. The 1.4MB emulation on these boards isn’t guaranteed to work, but maybe you’ll get lucky. :-)

These Floppy Emu boards have a built-in connector, and are physically identical to those that normally sell for $89.
 
Update: The scratch and dent boards have all been sold. Thanks for the interest!

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Fresh from the Factory

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It’s been quiet here in electronics hobby land, but I do have some good news to report: as of now, all Floppy Emu boards are professionally assembled by Microsystems Development Technologies in California, USA. No more hand assembly! It’s a glorious thing to receive a big box stuffed with assembled boards, and as good as a kid opening a package on Christmas Day. Microsystems wasn’t the cheapest option I found, but they weren’t too far off. I was convinced to go with them thanks to their quick and helpful answers to my many questions, and by their nearby location in San Jose. That’s a short drive from where I live, so when the boards were finished I was able to drive down there and meet the owner in person, and discuss potential changes for future board revisions. That alone was worth the cost difference versus slightly cheaper Asian alternatives.

Microsystems took my design files and bill of materials, and handled everything from there. They made the PCBs, purchased the parts, assembled everything, programmed the chips, and ran the board self-test. That’s a huge time savings for me, and it also removed a major source of potential faults because they handled all the tricky surface-mount work.

Unfortunately, the “finished” boards from Microsystems still aren’t quite ready to sell. It takes another 15-20 minutes of labor per board for me to attach a DB-19 connector (or build a DB-19 extension cable, depending on the type of board), assemble an LCD module, adjust the LCD contrast, and run the board through real-world file copy tests on a couple of vintage Macs. I thought Microsystems wouldn’t be able to handle those steps very easily, so I asked them to skip it. After more discussion, though, it looks like they can do everything except the file copy tests without much trouble. It’ll cost me a few extra dollars, but if it saves me time and headache, it’s probably worth it.

One bummer is that I’m still seeing a few boards that consistently fail my file copy tests, and can’t be sold. This happened sometimes with the old hand-assembled boards, and I never did find the cause, but I suspected it was related to my lousy hand-soldering job. But since it’s still happening with the professionally assembled boards, it’s probably some kind of design flaw. Ugh. For the time being I’m just setting these boards aside in the reject bin, but eventually when I’m sufficiently motivated I’ll see if I can figure out what’s wrong.

TL;DNR – While it doesn’t solve every problem, having professionals source the parts and assemble the boards is very nearly the best thing since sliced bread. I’m happy to give my soldering iron a well-deserved rest.

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Floppy Emu Backlight

I’m something of an anti-backlight guy, and I intentionally designed Floppy Emu with the LCD screen’s backlight disabled. Without the backlight, the text is crisp and the contrast is excellent. With the backlight, the text looks more washed out, and imperfections in the LCD glass become visible. Nevertheless, some people really want a backlight, so this post will show you how to hack your Floppy Emu to turn the backlight on.

The LCD already has four backlight LEDs built-in to the edges of the display, and all you need to do to enable them is solder a resistor or a piece of wire to the right pins. The procedure is slightly different, depending on which version of the LCD you have.

For Floppy Emus with serial numbers 51 and higher, connect the holes labeled LIGHT and GND at the top-right of the LCD with a low-value resistor, or a plain piece of wire. If you use a resistor, I recommend something in the range of 10 to 50 Ohms (lower values will give a brighter light). Because the LIGHT and GND pins are so close together, you’ll probably need to orient the resistor vertically, as shown in the photo. For the brightest backlight, use a plain piece of wire instead of a resistor. This won’t damage the LCD, because it already has a small backlight resistor built-in.

For Floppy Emus with serial numbers 1-50, the LCD design is slightly different. Connect a resistor between the pins labeled LED and VCC at the top of the board. You’ll probably find that there’s already a cut-off pin at those two spots, so you can solder your resistor to those pins. I recommend a resistor in the range of 47 to 100 Ohms. Don’t use plain wire here – these LCDs do not have any built-in resistors, and using them without any resistance may damage the LCD.

Some of the LCDs have a white backlight, and some have blue. It’s a surprise!

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