So. You Bought A VNA. Now What?

April 23, 2020 by Jenny List 33 Comments

It’s never too late in life for new experiences, but there’s a new experience I had a few weeks ago that I wasn’t expecting. I probably received my first piece of test equipment – a multimeter – in the early 1980s, and since then every time I’ve received a new one, whether an oscilloscope, logic analyser, spectrum analyser or signal generator, I’ve been able to figure out how to use it. I have a good idea what it does, and I can figure out whatever its interface may be to make it do what I want it to. My new experience came when I bought a piece of test equipment, and for the first time in my life didn’t have a clue how to use it.

That instrument is a Vector Network Analyser, or VNA, and it’s worth spending a while going through the basics in case anyone else is in the same position. My VNA is not a superlative piece of high-end instrumentation that cost the GDP of a small country, it’s the popular $50 NanoVNA that has a fairly modest frequency range and performance, but is still a functional VNA that can take useful measurements. But I’m a VNA newbie, what does a VNA do? Continue reading “So. You Bought A VNA. Now What?” →

Printed It: Collet Drill Stop

April 22, 2020 by Tom Nardi 25 Comments

You’d think that being quarantined in your home would be perfect for hackers and makers like us, as we all have a project or two that’s been sitting on the back burner because we didn’t have the time to tackle it. Unfortunately, some are finding that the problem now is actually getting the parts and tools needed to do the job. When there’s a bouncer and a line outside the Home Depot like it’s a nightclub on Saturday night, even the simplest of things can be difficult to source when making in the time of COVID.

Which is exactly the situation I found myself in recently when I needed to drill a bunch of holes to the same depth. The piece was too big to put in the drill press, and while I contemplated just wrapping the bit in some tape to serve as a makeshift stop, I wasn’t convinced it would be accurate or repeatable enough. It occurred to me that a set of drill stop collars would be easy enough to design and 3D print, but before I fired up OpenSCAD, I decided to see what was already available online.

Which is how I found the “Collet Drill Stop” from Adam Harrison. Rather than the traditional ring and setscrew arrangement, his design uses a printable collet that will clamp down on the bit at an arbitrary position without tools. So not only could I avoid a trip to the store by printing this design out, it looked like it would potentially be an upgrade over what I would have bought.

Of course, it’s wise not to take anything for granted when dealing with 3D printing. The only way I could be sure that Adam’s design would work for me was to commit it to plastic and try it out.

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Have JBC Soldering Handle, Will USB-C Power Deliver

April 21, 2020 by Kerry Scharfglass 8 Comments

Frequent converter-of-tools-to-USB-C [Jana Marie Hemsing] is at it again, this time with a board to facilitate using USB Power Delivery to fuel JBC soldering iron handles. Last time we saw [Jana] work her USB-C magic was with the Otter-Iron, which brought Power Delivery to the trusty TS100 with a purpose built replacement PCBA. This time he’s taking a different approach by replacing the “station” of a conventional soldering station completely with one tiny board and one giant capacitor.

If you’ve been exposed to the “AC fire starter” grade of soldering iron the name JBC might be unfamiliar. They make tools most commonly found with Metcal’s and high end HAKKOs and Wellers on the benches of rework technicians and factory floors. Like any tool in this class each soldering station comes apart and each constituent piece (tips, handles, base stations, stands, etc) are available separately from the manufacturer and on the used market at often reasonable prices, which is where [Jana] comes in.

The Otter-Iron PRO is a diminutive PCBA which accepts a USB-C cable on one side and the connector from a standard JBC T245-A handle on the other. JBC uses a fairly typical thermistor embedded in the very end of the iron tip, which the Otter-Iron PRO senses to provide closed loop temperature control. [Jana] says it can reach its temperature setpoint from a cold start in 5 seconds, which roughly matches the performance of an original JBC base station! We’re especially excited because this doesn’t require any modification to the handle or station itself, making it a great option for JBC users with a need for mobility.

Want to make an Otter-Iron PRO of your own? Sources are at the link at the top. It sounds like v3 of the design is coming soon, which will include its own elegant PCB case. Check out the CAD render after the break. Still wondering how all this USB-PD stuff works? Check out [Jason Cerudolo’s] excellent walkthrough we wrote up last year.

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Tubes Have Character With A Tek 570

April 20, 2020 by Al Williams 12 Comments

When tubes were king, you could go to a drugstore with a box full of them from your TV. There would be a tester that would tell you what tubes were bad and, of course, you could buy the replacements for them. That kind of tube tester was pretty simple. If you wanted to really know how to design with a tube or test its parameters, you were much better off with a curve tracer like the Tektronix 570 that [tomtektest] shows off in two recent videos that you can see below.

That piece of kit fell into [Tom’s] lap thanks to an observant delivery driver. The 1955 instrument is very similar to a semiconductor curve tracer but, of course, has the ability to provide much higher voltage for the tubes. The basic idea is that the X axis sweeps from a few volts up to 100s of volts. The vertical scale will show the plate, screen, or grid current. From those curves you can learn a lot about the characteristics of the tube.

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Measuring Sharpie Thickness… The Ink Itself, Not The Pen!

April 20, 2020 by Mike Szczys 29 Comments

How we missed this one from a few years ago is unknown, but we’re glad to catch up with it now. Have you ever needed to measure how thick the ink in a Sharpie line is? Of course you haven’t. But if you needed to, how would you do it? Using a wicked-sensitive indicator gauge and levering an interesting test setup.

[Tom] from [oxtoolco] got his hands on a tool that measures in 1/10,000,000th (that’s one ten-millionth) increments and was wondering what kind of shenanigans you can do with this Lamborghini of dial indicators. It’s one thing to say you’re going to measure ink, but coming up with the method is the leap. In this case it’s a gauge block — a piece of precision ground metal with precise dimensions and perfectly perpendicular faces. By zeroing the indicator on the block, then adding lines from the Sharpie and measuring again, you can deduce the thickness of the ink markings.

After arraying diagonal lines on the gauge block it is placed lines-down under the dial indicator. This distributes the ink layer across a larger area, as probing the ink line directly would likely result in inaccurate readings. On that topic the gauge block is moved using pliers, as introducing heat from your fingers could result in expansion of the metal upsetting the readings.

The results? Black, blue, and red Sharpie were all tested, alongside blue and black Dykem layout fluid. Ten samples of each were run and the readings were all very close, save a couple of obvious outliers. Clocking in the thinnest is black Sharpie at about 118 millionths of an inch (~30 microns) and blue Dykem was the thickest at 314 millionths (86 microns). [Tom] quips that since we now know the thickness, you could even use ink as a shim.

If you can’t get enough Sharpie in your life, try it as an extremely satisfying add-on for your plasma cutter.

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Gain An Understanding Of Injection Molding’s Design Gotchas

April 19, 2020 by Donald Papp 11 Comments

When it comes to manufacturing, sheet metal and injection molding make the world go ’round. As a manufacturing method, injection molding has its own range of unique design issues and gotchas that are better to be aware of than not. To help with this awareness, [studiored] has a series of blog posts describing injection molding design issues, presented from the perspective of how to avoid and address them.

Design of screw bosses demonstrating conflict between molder’s guidelines and vendor’s recommendations. Compromising between both is a science and an art.

Because injection molding involves heat, warp is one issue to be aware of and its principles will probably be familiar to anyone with nitty-gritty experience in 3D printing. Sink marks are also an issue that comes down to differential cooling causing problems, and can ruin a smooth and glossy finish. Both of these play a role in how best to design bosses.

Minimizing and simplifying undercuts (similar to overhangs in 3D printer parlance) is a bit more in-depth, because even a single undercut means much more complex tooling for the mold. Finally, because injection molding depends on reliably molding, cooling, and ejecting parts, designing parts with draft (a slight angle to aid part removal) can be a fact of life.

[studiored] seems to have been working overtime on sharing tips for product design and manufacture on their blog, so it’s worth keeping an eye on it for more additions. We mentioned earlier that much of the manufacturing world revolves around injection molding and sheet metal, so to round out your knowledge we published a primer on everything you need to know about the art and science of bending sheet metal. With a working knowledge of the kinds of design issues that affect these two common manufacturing methods, you’ll have a solid foundation for any forays into either world.

Perfect Wire Hose Clamps With A Simple DIY Tool

April 17, 2020 by Danie Conradie 31 Comments

Hose clamps have been around as long as we’ve been using flexible hoses. Usually, a clamp consists of a slotted metal strap, and a screw for tightening. Most of us know how quickly they slip when you want to add a bit more torque, or the frustration of not having the right size. Fortunately [Max Egorov] reminded us of DIY wire clamps (video after the break), an excellent alternative that is very effective, covers an infinite size range and is easy to make with a simple tool.

The wire clamp is in effect a doubled girth hitch, that is pulled tight with the ends bent over to keep the tension. [Max] shows you how to easily make your own clamper tool with basic tools and a few bits of steel. Making it as ornate as his one is definitely not required. You can also buy a commercial tool that is sold under the name ClampTite, which uses a leadscrew type design.

To achieve a tight seal with a hose clamp, the main requirement is constant pressure around its entire circumference. These wire clamps do this very well and are popular among aircraft mechanics, since flying in a plane with a leaky coolant or fuel hose could shorten your lifespan a bit. [Max] also demonstrates a variety of other uses for these including fixing tool handles and even building a ladder.

We love simple but effective tools like this, and we’ll definitely be adding one to our toolbox. Have you used these before? Let us know in the comments!

There is (almost) never such a thing as too many tools, and making your own is very satisfying. We’ve seen people build an outfit a complete carpentry workshop using plywood, and build sheet metal press brake with no welding.

Thanks [Keith O] for the tip!

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