If you’re a mechanical engineer, the material covered in this video on the basics of bolted joints probably won’t cover any new ground. On the other hand, if you aren’t a mechanical engineer but still need to bring a little of that discipline to your projects, there’s a lot to learn here.
If there’s one takeaway lesson from [The Efficient Engineer]’s excellent examination of the strength of bolted joints, it’s the importance of preload. Preload is the tensile force created by tightening a bolt or a screw, which provides the clamping force that keeps the joined members together. That seems pretty self-obvious, but there’s more to the story, especially with joints that are subject to cycles or loading and unloading. Such joints tend to suffer from fatigue failure, but proper preloading on the bolts in such a joint mitigates fatigue failure because the bolts are only taking up a small fraction of the total cyclical force on the joint. In other words, make sure you pay attention to factory torque specs.
Wait, what? Is it possible that a tech company just killed off a product with a huge installed base of hardware and a community of dedicated users, and it wasn’t Google? Apparently not, if the stories of the sudden demise of Insteon are to be believed. The cloud-based home automation concern seems to have just disappeared — users report the service went offline at the end of last week, and hasn’t been back since. What’s more, the company’s executives removed Insteon from their LinkedIn profiles, and the CEO himself went so far as to remove his entire page from LinkedIn. The reasons behind the sudden disappearance remained a mystery until today, when The Register reported that Smartlabs, Inc., the parent company of Insteon, had become financially insolvent after an expected sale of the company failed in March. The fact that the company apparently knew this was going to happen weeks ago and never bothered to give the community a heads up before pulling the switches has led to a lot of hard feelings among the estimated 100,000 Insteonhub users.
Then again, with a comet the size of Rhode Island heading our way, a bunch of bricked smart bulbs might just be a moot point. The comet, known as C/2014 UN271, has a nucleus that is far larger than any previously discovered comet, which makes it a bit of an oddball and an exciting object to study. For those not familiar with the United States, Rhode Island is said to be a state wedged between Connecticut and Massachusetts, but even having lived in both those states, we couldn’t vouch for that. For scale, it’s about 80 miles (128 km) across, or a little bit bigger than Luxembourg, which we’re pretty sure is mythical, too. The comet is a couple of billion miles away at this point; it may never get closer than a billion miles from the Sun, and that in 2031. But given the way things have been going these last few years, we’re not banking on anything.
From the “Answering the Important Questions” file, news this week of the Massachusetts Institute of Technology’s breakthrough development of the “Oreometer,” a device to characterize the physical properties of Oreo cookies. The 3D printed device is capable of clamping onto the wafer parts of the popular sandwich cookie while applying axial torque. The yield strength of the tasty goop gluing the two wafers together can be analyzed, with particular emphasis on elucidating why it always seems to stay primarily on one wafer. Thoughtfully, the MIT folks made the Oreometer models available to one and all, so you can print one up and start your own line of cookie-related research. As a starting point, maybe take a look at the shear strength of the different flavors of Oreo, which might answer why the world needs Carrot Cake Oreos.
And finally, since we mentioned the word “skiving” last week in this space, it seems like the all-knowing algorithm has taken it upon itself to throw this fascinating look at bookbinding into our feed. We’re not complaining, mind you; the look inside Dublin’s J.E. Newman and Sons bookbinding shop, circa 1981, was worth every second of the 23-minute video. Absolutely everything was done by hand back then, and we’d imagine that very little has changed in the shop over the ensuing decades. The detail work is incredible, especially considering that very few jigs or fixtures are used to ensure that everything lines up. By the way, “skiving” in this case refers to the process of thinning out leather using a razor-sharp knife held on a bias to the material. It’s similar to the just-as-fascinating process used to make heat sinks that we happened upon last week.
This week’s fail is an attempt to retrofit a PCB cutting shear with a geared motor. The project was undertaken by [David Cook]. Incidentally he’s very near and dear to us as his book Robot Building for Beginners got us started with hacking in the first place.
This $200 shearing tool is hand-operated and can cut through boards up to 1/16″ thick. But [David] really had to crank on the thing to make a cut. This often resulted in crooked board edges. He decided to do the retrofit in order to achieve higher precision. He sourced a high-torque motor from eBay for around $50 delivered.
