Cheap Caliper Hack Keeps ‘Em Running Longer

Many a hacker is a fan of the cheapest calipers on the market. Manufactured in China and priced low enough that they’re virtually disposable, they get a lot of jobs done in the world where clinical accuracy isn’t required. However, their batteries often die when left in a drawer for a long time. [Ben] was sick of that, and got to hacking.

The result was a quick-and-dirty mod that allows the calipers to be powered by a AAA battery. The average AAA cell has 5-10 times the capacity of the typical LR44 coin cells used in these devices.

[Ben] whipped this up with an eye to making it work rather than making it nice, so there are some shortcuts taken. The battery housing was 3D-printed on the lowest-quality settings that were viable, and it’s held to the calipers with hot glue. Similarly, bare wire ends were used instead of proper contacts, taking advantage of the battery being crammed in to make a good connection.

It’s a hack that will likely save [Ben] much frustration, as he’ll now rarely open his drawer to find his calipers dead. However, one [Pete Prodoehl] suggests another useful trick: store the calipers in the closed position with the lock screw tight to save them turning themselves on accidentally.

Whichever way you go, you’ve hopefully learned something today that will keep your cheap calipers working when you need them. Next, you might consider hacking them to capture data, too.

caliper jaw tools

Printable Caliper Jaws Increase Precision, Deflect Derision

If you’ve watched as many machining videos as we have, no doubt you’ve seen someone commit the cardinal sin of metalworking: using caliper jaws to scratch a mark into metal. Even if it’s a cheap Harbor Freight caliper rather than an expensive Starrett or Mitutoyo tool being abused, derision and scorn predictably rain down upon the hapless sinner’s head.

The criticism is not without its merit, of course. Recognizing this, [Nelson Stoldt] came up with these clamp-on nosepieces designed to turn calipers into a better marking tool. Using stock calipers as marking gauges always introduces some error, since the jaws are equal lengths and thus have to be held at a slight angle to the workpiece in order to make a mark. The caliper jaws correct for this admittedly negligible error by extending one jaw, allowing it to ride on a reference face while the other jaw remains perpendicular to the workpiece. As a bonus, the short jaw has a slot to mount a steel marking knife, saving the caliper jaws from damage.

[Nelson] chose to 3D-print his caliper jaws, but they could just as easily be milled from solid stock to make them a little more durable. Then again, you could always 3D-print the calipers in the first place, and integrate these jaws right into them.

Custom Caliper Tracks For When You’re Going The Distance

The working principle of digital calipers is mysterious enough that we’d never think to dismantle, much less improve them, right? Well, think again, as [Limi DIY] retrofits the processing element onto a custom track, extending the calipers measurement distance to a whopping 650 mm. Combined with a prior project to extract the measurement data, the result makes for a working multi-axis digital readout, a handy device for machine tools like a manual lathe or milling machine.

Digital calipers operate on the principle of measuring an array of variable capacitors. If we scratch our heads and look back at our physics notes, we’ll recall that the capacitance between two parallel conductive plates is linearly proportional to the surface area. By fixing one dimension of both plates and by sliding one plate over the other, we effectively change the area, giving ourselves a simple linear displacement sensor! (There are some classy error-correcting techniques too, and this [PDF] is a great place to look for more details.)

The theory takeaway is that this array of parallel plates can be embedded directly into a printed circuit board. We just need to know the dimensions. After some close measurement work, [Limi DIY] extracted the crucial measurements and fabbed a PCB with the pattern duplicated over 650 mm. After retrofitting the original processing element onto this new track, they had a working measurement device that’s far longer than the original!

If you’ve ever been tempted to disassemble your calipers but too nervous to bite off the investment, now’s your chance to follow along as [Lima DIY] demonstrates the gratuitous disassembly process for you in video format. And the fruits of their labor is also captured on a project post that includes the key dimensions if you’re looking to do the same thing.

If you’re looking for other ways to improve your calipers, why not start by giving them a major battery life boost.

Thanks to [absd] via [Jubilee Discord] for the tip!

Continue reading “Custom Caliper Tracks For When You’re Going The Distance”

3D Printed Calipers Work Like Clockwork

Most of us use calipers when working with our 3D printers. Not [Albert]. He has a clockwork caliper design that he 3D printed. The STL is available for a few bucks, but you can see how it works in the video below. We don’t know how well it works, but we’ll stick with our digital calipers for now.

The digital readout on this caliper is more like a sophisticated watch. A window shows 10s of millimeters and two dials show the single digits and the number after the decimal point.

Continue reading “3D Printed Calipers Work Like Clockwork”

Digital Caliper Talks For Accessibility, With This App

A good instrument stays with its owner for a lifetime, becoming part of their essential trusted toolkit to be consulted as a matter of habit. If you use a caliper to measure dimensions¬† you’ll know this, and a quick glance at its scale or digital display will be second nature. But if you aren’t fortunate enough to have the eyesight to see the caliper, then it’s off-limits, and that’s something [Naomi Wu] has addressed with her open-source accessible speaking caliper app. It’s an Android app that connects to digital calipers that contain Bluetooth connectivity, and as well as speaking aloud the caliper reading it also displays it in very large text on the device screen. As well as the source link from which you can build the app, it’s available for installation directly from the Google Play Store.

If you’re used to [Naomi] from her video tours of the electronics businesses in her native Shenzhen, her eye-catching wearable projects, or her exploits with an industrial CNC machine in her living room, you might be interested to know that aside from this app she’s been a long-time proponent of open-source in China. She was responsible among other projects for the Sino:bit educational computer board, which holds the distinction for her of having secured the first ever Chinese OSHWA certification.

You can see the caliper app in action below the break.

Continue reading “Digital Caliper Talks For Accessibility, With This App”

Vernier Calipers And Micrometer Screw Gauges, Measuring Without Compromise

I needed a temperature controller module recently, so off I went to Banggood to order one. As one does I found myself browsing, one thing led to another, and I bought a micrometer screw gauge. While micrometers are pretty expensive devices, reflecting their high precision engineering and construction, this micrometer cost me only about ¬£8, or just under $10, definitely in the spirit of our long-running series of reviewing very cheap tools in search of a diamond in the rough. But perhaps more importantly, this is also the cue for an examination of high precision dimensional measurement. So I’ve assembled a collection of micrometers and vernier calipers of varying quality, and it’s time to dive in and measure some very small things.

Some of you will be metrology enthusiasts with an array of the finest devices available, but I am guessing that many of you will not. The ubiquitous precision measurement device in our community appears to be the digital caliper, a sliding clamp with an LCD display, an instrument that can be had in its most basic form for a very small outlay indeed. For the purposes of this piece though we’re not looking at digital devices but their analogue precursors. If you want a feel for metrology and you’d like some of those heritage tools that parents pass onto their kids then it’s time to learn something about the vernier caliper and the micrometer. Continue reading “Vernier Calipers And Micrometer Screw Gauges, Measuring Without Compromise”

Making A Custom Caliper Case For Pros

Every professional has a tool set that they would never part with. Likewise, for experimental physicists, mechanical engineers, and tinkerers, a caliper set can be unspeakably crucial to their work. That’s why [Andrew Birkel] designed his own personal caliper set to fit just the right proportions for his tools while adding a bit of personal flair.

The project uses CNC routing, Solidworks for CAD, laser engraving, and woodworking to design the custom case for a set of calipers, metric and English screw pitch gauges, fillet gauges, and radius gauges. It’s a practical build for a custom tool set that doesn’t already come with a case of its own. The particular tools were chosen for their use in particle physics experiments: for determining threads, inside and outside curvatures, and measuring length, depth, and width.

The box was made from an oversized piece of wood with holes drilled into the sides. After compiling the G-code program for the build, the two halves of the box was was milled from the wood. The first run on the CNC mill with aluminum managed to cause the grain to split, so [Birkel] went with a CNC router instead. Once the piece was sanded, hidden barrel hinges were added. The finished box was wiped down with mineral oil and teak oil to bring out the natural coloration of the wood as well as to add protection (lacquer mixed into the oil). To finish it off, the case was customized with a laser engraved name and email for identification.

It’s a pretty slick build to say the least, and certainly one that can be customized to the dimensions of whatever tools your personal caliper set happens to have.