Shop-Made Pneumatic Cylinders From PVC And Plywood

September 11, 2018 by Dan Maloney 26 Comments

You see a lot of pneumatic actuators in industrial automation, and for good reason. They’re simple, powerful, reliable, and above all, cheap. Online sources and fluid-power suppliers carry a bewildering range of actuators, so why would anyone bother to make their own pneumatic cylinders? Because while the commercial stuff is cheap, it’s not PVC and plywood cheap.

Granted, that’s not the only reason [Izzy Swan] gives for his DIY single-acting cylinder. For him it’s more about having the flexibility to make exactly what he needs in terms of size and shape. And given how ridiculously easy these cylinders are, you can make a ton of them for pennies. The cylinder itself is common Schedule 40 PVC pipe with plywood endcaps, all held together with threaded rod. [Izzy] cut the endcaps with a CNC router, but a band saw or jig saw would do as well. The piston is a plywood plug mounted to a long bolt; [Izzy] gambled a little by cutting the groove for the O-ring with a table saw, but no fingers were lost. The cylinder uses a cheap bungee as a return spring, but an internal compression spring would work too,. Adding a second air inlet to make the cylinder double-acting would be possible as well. The video below shows the cylinder in action as a jig clamp.

True, the valves are the most expensive part of a pneumatic system, but if nothing else, being able to say you made your own cylinders is a win. And maybe you’ll get the fluid-power bug and want to work up to DIY hydraulics.

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How Big Is Your Oscilloscope? One Inch?

September 11, 2018 by Al Williams 30 Comments

We are anxious to see the finished product of [Mark Omo’s] entry into our one square inch project. It is a 20 megasample per second oscilloscope that fits the form factor and includes a tiny OLED screen. We will confess that we started thinking if you could use these as replacements for panel meters or find some other excuse for it to exist. We finally realized, though, that it might not be very practical but it is undeniably cool.

There are some mockup PCB layouts, but the design appears feasible. A PIC32MZ provides the horsepower. [Mark] plans to use an interleaved mode in the chip’s converters to get 20 megasamples per second and a bandwidth of 10 MHz. It appears he’ll use DMA to drive the OLED. In addition to the OLED and the PIC, there’s a termination network and a variable gain stage and that’s about it.

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3D Printed Radius Gauge, Just Add Calipers (And A Wee Bit Of Math)

September 9, 2018 by Donald Papp 16 Comments

With 3D printed arms of fixed measurements, the depth reading from a set of digital calipers can be used to calculate the radius of a curve.

Specialized tools that focus on one particular job tend to get distilled right down to their essentials and turned in an economical consumer product. One example of this is radius (or fillet) gauges: a set of curves in different sizes that one uses to measure the radius of a curved surface by trial and error. To some, such products represent solved problems. Others see opportunities for a fresh perspective, like this caliper-enabled 3D printed radius gauge by [Arne Bergkvist].

[Arne]’s 3D printed radius gauge is a simple object; a rigid attachment for a nearly ubiquitous model of digital caliper. By placing the curve to be measured between the two arms of the device and using the depth measurement of the caliper to measure distance to the curve’s surface, a simple calculation (helpfully printed on the unit itself) of radius = distance * 2.414 reveals the radius of the curve. However, this shortened calculation makes a number of assumptions and only works for [Arne]’s specific design.

Another version by [Fredrik Welander] represents a more flexible take on the same concept. His RadGauge design (pictured up top) has a few different sizes to accommodate a variety of objects, and his Git repository provides a calculator tool as well as some tips on fine tuning to allow for variations in the dimensions of the printed attachment.

3D printing has opened a lot of doors, and items like this show that the plastic doodads created aren’t always the end result in and of themselves; sometimes they are the glue that enables a tool or part to work in a different way. To help get the most out of 3D printing, check out the in-depth coverage of how to best tap 3D printed parts for fasteners, and [Roger Cheng]’s guide to using 3D printed brackets and aluminum extrusion to make just about anything.

The How And Why Of Tungsten Carbide Inserts, And A Factory Tour

September 7, 2018 by Dan Maloney 11 Comments

It seems a touch ironic that one of the main consumables in the machining industry is made out of one of the hardest, toughest substances there is. But such is the case for tungsten carbide inserts, the flecks of material that form the business end of most of the tools used to shape metal. And thanks to one of the biggest suppliers of inserts, Sweden’s Sandvik Coromant, we get this fascinating peek at how they’re manufactured.

For anyone into machining, the video below is a must see. For those not in the know, tungsten carbide inserts are the replaceable bits that form the cutting edges of almost every tool used to shape metal. The video shows how powdered tungsten carbide is mixed with other materials and pressed into complex shapes by a metal injection molding process, similar to the one used to make gears that we described recently. The inserts are then sintered in a furnace to bind the metal particles together into a cohesive, strong part. After exhaustive quality inspections, the inserts are ground to their final shape before being shipped. It’s fascinating stuff.

Coincidentally, [John] at NYC CNC just released his own video from his recent jealousy-inducing tour of the Sandvik factory. That video is also well worth watching, especially if you even have a passing interest in automation. The degree to which the plant is automated is staggering – from autonomous forklifts to massive CNC work cells that require no operators, this looks like the very picture of the factory of the future. It rolls some of the Sandvik video in, but the behind-the-scenes stuff is great.

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Save Fingers, Save Lives With A No-Voltage Release For The Shop

September 6, 2018 by Dan Maloney 41 Comments

Imagine the scenario: you’re spending some quality time in the shop with your daughter, teaching her the basics while trying to get some actual work done. You’re ripping some stock on your cheap table saw when your padiwan accidentally hooks the power cord with her foot and pulls out the plug. You have a brief chat about shop safety and ask her to plug it back in. She stoops to pick up the cord and plugs it back in while her hand is on the table! Before you can stop the unfolding tragedy, the saw roars to life, scaring the hell out of everyone but thankfully doing no damage.

If that seems strangely specific it’s because it really happened, and my daughter was scared out of the shop for months by it. I’ll leave it to your imagination what was scared out of me by the event. Had I only known about no-voltage release switches, or NVRs, I might have been able to avoid that near-tragedy. [Gosforth Handyman] has a video explaining NVRs that’s worth watching by anyone who plugs in anything that can spin, cut, slice, dice, and potentially mutilate. NVRs, sometimes also called magnetic contactors, do exactly what the name implies: they switch a supply current on and off, but automatically switch to an open condition if the supply voltage fails.

Big power tools like table saws and mills should have them built in to prevent a dangerous restart condition if the supply drops, but little tools like routers and drills can still do a lot of damage if they power back up while switched on. [Gosforth] built a fail-safe power strip for his shop from a commercial NVR, and I’d say it’s a great idea that’s worth considering. Amazon has a variety of NVRs that don’t cost much, at least compared to the cost of losing a hand.

True, an NVR power strip wouldn’t have helped me with that cheap table saw of yore, but it’s still a good idea to put some NVR circuits in your shop. Trust me, it only takes a second’s inattention to turn a fun day in the shop into a well-deserved dressing down by an angry mother. Or worse.

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ZPB30A1 Electronic Load Gets An Open Firmware

September 6, 2018 by Tom Nardi 30 Comments

Importing cheap equipment and test gear is something of a mixed blessing. It allows you to outfit your lab without emptying your bank account, but on the other hand there’s usually a reason it’s cheap. Of course, the retail price of a piece of hardware shouldn’t be the metric by which we measure its quality, but there’s got to be a few corners cut someplace when they are selling this stuff for a fraction of what the name brands are charging.

A perfect example is the ZHIYU ZPB30A1 electronic load, available from various online importers for about $30 USD. While the price is right for an adjustable load that can handle up to 110 W, it’s got some pretty glaring shortcomings. In an effort to address at least some of those issues, [Luca Zimmermann] has been working on an open source replacement firmware for the load’s STM8S microcontroller.

[Luca] quickly discovered that the device’s STM8S005K6 chip is write protected, so unfortunately you can’t just flash a new firmware to it. If you want to unlock additional features, you need to perform a brain transplant. Luckily these chips are quite cheap, and you can probably add a couple of them to your cart when you order he ZPB30A1.

With the new GPLv3 licensed firmware installed, the device gains constant power and resistances modes (stock firmware can only do constant current), serial logging, and support for adjusting the value of the shunt resistor. There’s even a basic menu system to shuffle through the new modes. There’s still a couple features that haven’t been implemented, such as automatic shutdown, but it’s already a considerable upgrade from the stock software. Now we just need some details on the slick custom enclosure that [Luca] has put his upgraded ZPB30A1 into.

If this looks too easy, you can always go the DIY Arduino route for your load testing needs, or build a monster than can sink up to 1 kW.

[Thanks to Benik3 for the tip.]

Interactive KiCAD BOMs Make Hand Assembly A Breeze

September 4, 2018 by Kerry Scharfglass 26 Comments

We’ve all been there; you finally get the last DigiKey box and now your desk is covered in parts to stuff into a shiny new PCB you’ve been working on. First stop? Passive town, population endless waves of 1uF capacitors. The first one goes in the upper left, then a little below that, then… once you get to C157 it’s getting pretty hard to remember exactly which parts go where. Enter the literally named InteractiveHtmlBom (IHB) to smooth this process out.

IHB makes the frustrating task of mapping lines in a BOM to a physical position on a board easy. The classic method is of course, to look at the BOM, then search the board for that designator and place the component. (You left the designators in the silk, right?) Or to look at the BOM, ask your CAD package to search for that part in the layout, then place. IHB generates a document that does this automagically.

Run the tool, either standalone or as a plugin for KiCAD 5.0, and you get a folder with the new interactive BOM in it. There are a few view options but generally it presents a view of the BOM with designators and value in one pane and a wonderful render of the top and/or bottom of the board in another pane. When you hover over a BOM line it highlights the relevant parts in the board view! There are toggles for filtering by top and bottom of board, marking which parts have been placed, light and dark mode, etc. Plus the ability to filter and sort by designator and value. We would have been impressed if it was just a generator/viewer for those slick scrollable/pannable board renders!

Check out a very long GIF demo after the break, or explore one of many pre-created demo BOMs here. We’re partial to the OSPx201.

Thanks [GregDavill] for the tip!

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