Treadmill To Belt Grinder Conversion Worked Out

[Mike] had a bunch of disused fitness machines lying around. Being a skilled welder, he decided to take them apart and put them back together in the shape of a belt grinder.

In particular, [Mike] is reusing the height-adjustment guide rail of an old workout bench to build the adjustable frame that holds the sanding belt. A powerful DC motor including a flywheel was scavenged from one treadmill, the speed controller came from another. [Mike] won’t miss the workout bench: Once you’re welding a piece of steel tube dead-center on a flywheel, as happened for the grinder’s drive wheel, you may call yourself a man (or woman) of steel.

The finished frame received a nice paint job, a little switching cabinet, proper running wheels and, of course, a sanding belt. Despite all recycling efforts, about 80 bucks went into the project, which is still a good deal for a rock-solid, variable-speed belt grinder.

Apparently, disused fitness devices make an ideal framework to build your own tools: Strong metal frames, plentiful adjustment guides, and strong treadmill motors. Let us know how you put old steel to good use in the comments and enjoy [Mike’s] build documentation video below!

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Open Design Oscilloscope Could be (Almost) Free

If you could only own one piece of test equipment, it should probably be an oscilloscope. Then again, modern scopes often have multiple functions, so maybe that’s not a fair assertion. A case in point is the Scopefun open hardware project. The device is a capable 2-channel scope, a logic analyzer and also a waveform and pattern generator. The control GUI can work with Windows, Linux, or the Mac (see the video, below).

The hardware uses a Xilinx Spartan-6 FPGA. A GUI uses a Cypress’s EZ-USB FX2LP chip to send configuration data to the FPGA.  Both oscilloscope channels are protected for overvoltage up to +/- 50 V. The FPGA samples at 100 Mhz through a 10-bit dual analog-to-digital converter ( ADC ). The FPGA handles triggering and buffers the input before sending the data to the host computer via the USB chip. Each channel has a 10,000 sample buffer.

There are also two generator outputs with short circuit and overvoltage protection ( +/- 50 V ). Generator channels have 50 Ohm internal impedance and also operates via the GUI using the same USB chip. The FPGA generates signals at 50 Mhz using counters, algorithms, or simple waveform data and feeds a DAC.

A 16-bit digital interface can be set as inputs or outputs. The FPGA samples inputs at 100 MHz. The output voltage can be set, but inputs are 5 V tolerant.

According to the developer, you can build the scope from the information provided by using free sample chips from the various vendors, only paying for the small components and the cost of the PCB.

We’ve looked at several low-cost scope options before. Labtool even boasts some similar features.

A Quickly-Hacked-Together Avalanche Pulse Generator

There are times when you make the effort to do a superlative job in the construction of an electronic project. You select the components carefully, design the perfect printed circuit board, and wait for all the pieces to come together as they come in the mail one by one. You then build it with tender care and attention, printing solder paste and placing components by hand with a fastidious attention to detail. There follows an anxious wait by the reflow oven as mysterious clouds of smoke waft towards the smoke detector, before you remove your batch of perfect boards and wait for them to cool.

Alternatively, there are other times when you want the device but you’re too impatient to wait, and anyway you’ve only got half of the components and a pile of junk. So you hack something a bit nasty together on the copper groundplane of a surplus prototype PCB in an evening with ‘scope and soldering iron. It’s not in any way pretty but it works, so you use it and get on with your life.

Our avalanche pulse generator schematic. The pulse generator itself is the single 2N3904 on the right.
Our avalanche pulse generator schematic. The pulse generator itself is the single 2N3904 on the right.

When you are a Hackaday writer with some oscilloscope bandwidths to measure, you need a picosecond avalanche pulse generator, and you need one fast. Fortunately they’re a very simple circuit with only one 2N3904 transistor, but the snag is they need a high voltage power supply well over 100 V. So the challenge isn’t making the pulse generator, but making its power supply.

For our pulse generator we lacked the handy Linear Technologies switcher used by the avalanche pulse generator project we were copying. It was time for a bit of back-to-basics flyback supply creation, robbing a surplus ATX PSU for its base drive transformer, high voltage diode and capacitor, and driving it through a CRT line output transistor fed by a two-transistor astable multivibrator. Astoundingly it worked, and with the output voltage adjusted to just over 150V the pulse generator started oscillating as it should.

We’ve looked at avalanche pulse generators once before here at Hackaday, and very recently we featured one used to measure the speed of light. We’ll be using this one tomorrow for a ‘scope comparison.

A Desk Lamp Solder Fume Extractor

Those of us who have spent a lifetime building electronic projects have probably breathed more solder smoke than we should. This is not an ideal situation as we’ve probably increased our risk of asthma and other medical conditions as a result.

It has become more common over the years to see fume extraction systems and filters as part of the professional soldering environment, and this trend has also started to appear in the world of the home solderer. As always, where commercial products go the hardware hacker will never be far behind. We’ve seen people producing their own soldering fume filters using computer fans.

A particularly neat example comes via [Engineer of None], who has posted an Instructable and the YouTube video shown below the break for a filter mounted on a desk lamp. A toaster is used to heat a piece of acrylic. The softened plastic is then shaped to fit the contours of the lamp. The lamp’s articulated arm is perfect for placing light and fume extraction exactly where it is needed. It’s not the most complex of hacks, but we’d have one like it on our bench without a second thought. We would probably add an activated carbon filter to ours though.

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Multimeter Probe Goes Full Circle

You’ve probably seen tweezers act as test probes for a multimeter or other instrument. Some electronics testing tweezers even have the multimeter built right in. Tools like these are especially handy for working with surface mount components. [Bweed2] found a probe made by E-Z hook that kept a fixed distance you can set with a thumbwheel. It looked good, but the $70-$80 price tag seemed too much.

Employing hacker ingenuity, he turned to a drafting compass. You know, the tool you use to draw circles. He picked up one for about $10 and then got some cheaper compasses to scavenge their needles (the compass usually only has one needle since the other side holds a pencil). The result was a useful set of adjustable probes.

Once you have the idea, it is a pretty simple project. Immobilize the knee of the compass with glue, connect some wires and–for extra points–add some red and black heat shrink to make it pretty.

Want to make a more classic SMD tweezer? Here’s one we’ve covered before. If you’d rather use your feet and your ears with your probes, you might be interested in these.

How To Have an Above Average Time With a Cheap Horizontal Bandsaw

[Quinn Dunki] has brought yet another wayward import tool into her garage. This one, all covered in cosmoline and radiating formaldehyde fumes, is a horizontal bandsaw.

Now, many of us have all have some experience with this particular model of horizontal saw. It waits for us at our work’s machine shop, daring us to rely on it during crunch time. It lingers in the corner of our hackerspace’s metalworking area, permanently stuck in the vertical position; at least until someone finally removes that stripped screw. Either that or it’s been cannibalized for its motor, the castings moldering in a corner of the boneyard.

This article follows on the heels of [Quinn]’s other work, a treatise on the calibration of a drill press, and it outlines all the steps one has to take to bring one of these misunderstood tools into consistent and reliable operation. It starts with cultivating a healthy distrust of the factory’s assurances that this device is, “calibrated,” and needs, “no further attention.” It is not, and it does. Guides have to be percussively maintained out of the blade’s way. Screws have to be loosened and adjusted. It takes some effort to get the machine running right and compromises will have to be made.

In the end though, with a high quality blade on, the machine performs quite well. Producing clean and quality cuts in a variety of materials. A welcome addition to the shop.

Home-Made Metal Brake

Sometimes, the appropriate application of force is the necessary action to solve a problem. Inelegant, perhaps, but bending a piece of metal with precision is difficult without a tool for it. That said, where a maker faces a problem, building a solution swiftly follows; and — if you lack a metal brake like YouTuber [makjosher] — building one of your own can be accomplished in short order.

Drawing from numerous online sources, [makjosher]’s brake is built from 1/8″ steel bar, as well as 1/8″ steel angle. The angle is secured to a 3/4″ wood mounting plate. Displaying tenacity in cutting all this metal with only a hacksaw, [makjosher] carved slots out of the steel to mount the hinges, which were originally flush with the wood. He belatedly realized that they needed to be flush with the bending surface. This resulted in some backtracking and re-cutting. [Makjosher] then screwed the pivoting parts to the wood mount. A Box tube serves as a handle. A coat of paint  finished the project, and adding another tool to this maker’s kit.

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