Building A Real Wooden Table Saw

January 11, 2020 by 43 Comments

A table saw is one of those tools that aren’t strictly necessary to have, but immensely helpful if you do happen to have one around. The folks at [I Build It] have made a three part series that features a homemade table saw build, so you can finally get around to adding one to your makerspace.

The build uses a real table saw arbor and is made from Baltic birch plywood and solid wood, with some plastic sheets for the trunnions and top. The blade is housed in a blade lift made out wooden panels with a pivot point and slot for the lift mechanism. Bearings allow the blade the freedom of movement, while a curved cutout allows it to stay flat against the wall of the slot while the blade lift mechanism moves.

Meanwhile a reused motor from a previous table saw is dusted, cleaned, and rewired to run in reverse. While most table saws only need two trunnions, a third is used for supporting the motor, since it has to move with the lift and tilt. Once the lift/tilt mechanism is complete, the frame for the table saw is more straightforward, with many steps involving clamping, measuring, cutting, fitting, and painting the assembly. For the final few steps, a switched is mounted outside the table saw in a small box that connected to the power supply and motor, as well as a shop vac for handling dust collection from the saw. While the enclosure isn’t a metal box, as long as the connections are secured properly the wires shouldn’t come loose.

If you want to see other examples of homemade table saws, check out this teeny tiny saw and this kid-friendly table saw build.

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This Ugly Christmas Sweater Can Set You On Fire

January 11, 2020 by 9 Comments

While Christmas may have just passed, there’s just enough time left in winter to justify wearing your ugly Christmas sweaters for a few more days. If you’re not one of the lucky ones with an old sweater from Grandma, you can still turn your least favorite sweater into the most epic flame-throwing Christmas sweater there ever was.

[JAIRUS OF ALL], maker of explosive and other dangerous ideas, came up with a DIY ugly Christmas sweater that shoots flames on command. In order to produce the flame-throwing effect, he uses piping from a fish tank airline hose with a T connector attached to one end and epoxied to the middle of the sweater. The piping runs down the sweater to a can of butane fuel that he can control from the nozzle. Once the fuel is being released, he uses a lighter to initiate the flames from the sweater.

The flames are quite impressive, so definitely use caution if you intend to replicate this build in any way. It would be helpful to have a friend with a CO2 fire extinguisher nearby as well.

For a less life-threatening build, fellow builder [Price] created a Christmas tree-themed sweater lined with LEDs and USB-powered figurines, connected to a power supply in his pocket.

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A Simple POV Globe Via APA102

January 10, 2020 by 31 Comments

POV builds come in all shapes and sizes, and typically rely on LEDs for their high light output and fast response time. With this in mind, [Great Scott] grabbed some LED strip off the shelf and set about whipping up a POV LED globe.

Being a spinning POV build, it’s necessary to consider how to get power to the rotating elements. [Great Scott] decided to go with a simple solution of putting a LiPo battery on the rotating assembly, which runs the LEDs and Arduino Nano at the heart of the operation. The LEDs in question are of the APA102 type, making them readily addressable and capable of a wide color gamut. It’s all spun by a simple brushed DC motor, running from a separate supply at the base of the platform.

It’s very much a hacker build, held together with duct tape and zipties. Despite this, it looks tidy when in operation, as all of the important hardware is hidden at the centre of the globe. There’s a bit of a vibration problem, but [Great Scott] reckons this can be fixed with some frame modifications.

We’d love to see the build run some more advanced operations, like a representation of the Earth, or some kind of sun clock. If you’re interested in learning more about POV displays, we’ve got the primer you need. Video after the break.

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Building A Low-Tech Website For Energy Efficiency

January 10, 2020 by 38 Comments

In an age of flashy jQuery scripts and bulky JavaScript front-end frameworks, loading a “lite” website is like a breath of fresh air. When most of us think of lightweight sites, though, our mind goes to old-style pure HTML and CSS sites or the intentionally barebones websites of developers and academics. Low-tech Magazine, an intentionally low-tech and solar-powered website, manages to incorporate both modern web aesthetics and low-tech efficiency in one go.

Rather than hosting the site on data centers – even those running on renewable power sources – they have a self-hosted site that is run on solar power, causing the site to occasionally go off-line. Their model contrasts with the cloud computing model, which allows more energy efficiency at the user-side while increasing energy expense at data centers. Each page on the blog declares the page size, with an average page weight of 0.77 MB, less than half of the average page size of the top 500,000 most popular blogs in June 2018.

Some of the major choices that have limited the size of the website include building a static site as opposed to a dynamic site, “dithering” images, sparing a logo, staying with default typefaces, and eliminating all third-party tracking, advertising services, and cookies. Their GitHub repository details the front-end decisions  including using unicode characters for the site’s logo rather than embedding an SVG. While the latter may be scalable and lightweight in format it requires distribution to the end-user, which can involve a zipped package with eps, ai, png, and jpeg files in order to ensure the user is able to load the image.

As for the image dithering, the technique allows the website to maintain its characteristic appearance while still minimizing image quality and size. Luckily for Low-tech Magazine, the theme of the magazine allows for black and white images, suitable for dithering. Image sprites are also helpful for minimizing server requests by combining multiple small images into one. Storage-wise, the combined image will take up less memory and only load once.

There are also a few extraneous features that emphasize the website’s infrastructure. The background color indicates the capacity of the solar-charged battery for the website’s server, while other stats about the server’s location (time, sky conditions, forecast) also help with making the website availability in the near future more visible. Who knows, with the greater conscience on environmental impact, this may be a new trend in web design.

Arduino Pedometer Counts Your Steps

January 10, 2020 by 10 Comments

There’s a trend in corporate America that has employees wear a step counter — technically a pedometer — and compete in teams to see who can get the most number of steps. We wonder how many people attach the device to an electric drill and win the competition easily. However if you want to do your own measurements, [Ashish Choudhary] has plans for making a pedometer with an Arduino. The device isn’t tiny, but as you can see in the video below it seems to work.

For the extra size, you do get some features. For one, there is a 16×2 LCD display and an ADXL335 accelerometer, and you can probably imagine some other cool features for such a device.

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Retro PowerBook Gets A Mac Mini Transplant

January 10, 2020 by 8 Comments

Around these parts, seeing a classic laptop or desktop computer get revived with the Raspberry Pi is fairly common. While we’re not ones to turn down a well-executed Pi infusion, we know they can be controversial at times. There’s an impression that such projects are low-effort, and that the combination of old and new tech gains little in the way of usability due to the usability quirks of the Pi itself.

But we think even the most critical in the audience will agree that this build by [Tylinol], which sees the internals of a circa 1993 PowerBook 165c get replaced with that of a 2014 Mac Mini, is something else entirely. For one thing, there’s no question that packing a modern (relatively) desktop computer motherboard into a laptop’s body takes a lot more planning and effort than hot gluing the comparatively tiny Pi into the same space. Plus as an added bonus, anyone who counts themselves among the Cult of Mac will be happy to see the vintage machine retain its Cupertino pedigree.

So how do you get a Mac Mini inside of a PowerBook? Very carefully. As explained by [Tylinol], the inside of the PowerBook’s case was coated in graphite and conductive enough to be a problem. So after the original hardware was removed, a layer of tape was added to insulate it; though we imagine a suitably thick spray-on coating could be used as well if you don’t have that kind of patience.

Once the case was gutted and insulated, [Tylinol] added new stand-offs to mount the Mac Mini motherboard and hard drive. For anyone wondering, the 2014 model was used because the shape of the board almost perfectly fits around the trackball PCB. A board from a newer Mac could be used, but it would likely mean using an external mouse.

Which would have been a problem for [Tylinol], because one of the main goals of this build was to get the original input working. That meant adapting the Apple Desktop Bus (ADB) devices to USB, which turns out to be something of a Dark Art. But with the help of some contemporary information about the long-forgotten protocol and a Teensy 3.5, both devices are now picked up as standard USB HID.

But of course, that’s just scratching the surface. [Tylinol] also had to figure out how to swap the original display out for a modern panel, and then get the whole thing running on internal battery power. Even if you’re not particularly interested in retro Apple hardware, this is really a phenomenal build that deserves a thorough read-through.

For those of you who don’t mind getting a Pi in a PowerBook, we recently saw a recreation of Lord Nikon’s laptop from Hackers that went that route.

Using Lookup Tables To Make The Impossible Possible

January 10, 2020 by 60 Comments

Embarrassing confession time: I never learned my multiplication tables in grade school. Sure, I had the easy tables like the twos and the fives down, but if asked what 4 x 7 or 8 x 6 was, I’d draw a blank. As you can imagine, that made me a less than stellar math student, and I was especially handicapped on time-limited tests with lots of long multiplication problems. The standard algorithm is much faster when you’ve committed those tables to memory, as I discovered to my great woe.

I was reminded of this painful memory as I watched Charles Lohr’s 2019 Supercon talk on the usefulness and flexibility of lookup tables, or LUTs, and their ability to ease or even completely avoid computationally intensive operations. Of course most LUT implementations address problems somewhat more complex than multiplication tables, but they don’t have to. As Charles points out, even the tables of sines and logarithms that used to populate page after page in reference books have been ported to silicon, where looking up the correct answer based on user input is far easier than deriving the answer computationally.

Yes, this is a Minecraft server all thanks to LUTs.

One of the most interesting examples of how LUTs can achieve the seemingly impossible lies in an old project where Charles attempted to build a Minecraft server on an ATMega168. Sending chunks (the data representations of a portion of the game world) to clients is the essential job of a Minecraft server, and on normal machines that involves using data compression. Rather than trying to implement zlib on an 8-bit microcontroller, he turned to a LUT that just feeds the raw bytes to the client, without the server having the slightest idea what any of it means. A similar technique is used by some power inverters, which synthesize sine wave output by feeding one full cycle of values to a DAC from a byte array. It’s brute force, but it works.

Another fascinating and unexpected realization is that LUTs don’t necessarily have to be software. Some can be implemented in completely mechanical systems. Charles used the example of cams on a shaft; in a car’s engine, these represent the code needed to open and close valves at the right time for each cylinder. More complicated examples are the cams and gears once found in fire control computers for naval guns, or the programming cards used for Jacquard looms. He even tips his hat to the Wintergatan marble machine, with its large programming drum and pegs acting as a hardware LUT.

I found Charles’ talk wide-ranging and fascinating. Originally I thought it would be an FPGA-heavy talk, but he didn’t actually get to the FPGA-specific stuff until the very end. That worked out fine, though — just hearing about all the cool problems a LUT can solve was worth the price of admission.

And for the curious, yes, I did eventually end up memorizing the multiplication tables. Oddly, it only clicked for me after I started playing with numbers and seeing their relationships using my first calculator, which ironically enough probably used LUTs to calculate results.

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