Autonomous Mower Hits Snag

Interfacing technology and electronics with the real world is often fairly tricky. Complexity and edge cases work their way in to every corner of a project like this; just ask anyone who has ever tried to operate a rover on Mars, make a hydroponics garden, or build almost any robotics project. Even those of us who simply own a consumer-grade printer are flummoxed by the ways in which they can fail when manipulating single sheets of paper. This robotic lawnmower is no exception, driving its creator [TK] to extremes to get it to mow his lawn.

[TK] actually had a platform for his autonomous mower ready to go thanks to a previous build using this solar-powered robot to explore the Australian outback. Adding another motor to handle the grass trimming seemed simple at first and he set about wiring it all up and interfacing it to the robot. After the first iteration he found the robot was moving too fast to effectively cut the grass, so he added a more powerful cutting motor and a gearbox to help the mower crawl more slowly over the lawn. Disaster struck when his 3D printed mount for the steel cutting blades shattered, but with [TK] uninjured he pushed on with more improvements.

As it stands right now, the mower can effectively cut the grass moving forward even with the plastic-only cutting blades that [TK] is using now for safety reasons. The mower stripped its reverse gear so there still are some improvements to make before this robot is autonomously cutting the lawn without supervision. Normally we see lawnmowers retrofitted with robotics rather than robotics retrofitted with a lawnmower, but we’re excited to see any approach that lets us worry about one less household chore.

Thanks to [Rob] for the tip!

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World's longest hacksaw

Fail Of The Week: A Bigger Hacksaw Isn’t A Better Hacksaw

If we’re being honest, the main reason to buy a power tool is to avoid the pain of using one’s muscles. Oh sure, we dress it up with claims that a power tool will make us more productive, or give better results, but more often than not it’s the memory of how your forearm feels after a day of twisting a screwdriver that makes you buy a cordless driver.

It appears that [Artisan Makes] has a high tolerance for pain, seeing how the main prep tool in his metal shop is a plain old hacksaw. So in an effort to speed up his stock prep, he turned not to a bandsaw or cutoff saw, but instead built the world’s silliest hacksaw. It’s the metalworking equivalent of the two-man bucksaws that lumberjacks used to fell trees before chainsaws came along, and at a meter and half in length, it’s about the size of one too. Modifying the frame of his trusty hacksaw was easy — he just popped the end pieces off and attached them to an extra-long piece of tube stock. Finding a 1.5-meter hacksaw blade was the main challenge; not exactly a big-box store item, that. So a section of metal-cutting bandsaw blade was modified to fit the frame, and it was off to the races.

Or not. The video below tells the tale of woe, which starts with the fact that [Artisan]’s shop is too small for the hilariously long hacksaw. Solving the fixturing problems didn’t soo much to help, though — there was no way to tension the blade enough to get it to stop wobbling during cutting. It was also clear that the huge saw wasn’t able to apply enough downforce on the stock to get good cuts. Maybe with a second set of hands, though…

There are plenty of ways to improve hacksawing in the shop, and while this isn’t one of them, we sure appreciate the chuckle we got out of it. And you really should check out [Artisan Makes]’ channel — his more serious stuff is really good.

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Keep The Sparks Away With A Plasma Cutting Table

For one-off projects or prototypes it’s not uncommon for us to make do with whatever workspace we have on hand. Using a deck railing as an impromptu sawhorse, for example, is one that might be familiar to anyone who owns a circular saw, but [Daniel] has a slightly different situation. He had been setting up metal workpieces on random chunks of brick in order to use his plasma cutter, but just like the home handyman who gets tired of nicking their deck with a saw, he decided to come up with a more permanent solution and built a custom plasma cutting table.

Plasma cutting has a tendency to throw up a lot of sparks, so most commercial offerings for plasma cutting tables include a water bath to catch all of the debris from the cutting process. [Daniel] builds his table over a metal tub to hold some water for this purpose. The table itself is built out of aluminum and designed to be built without welding even though most people with plasma cutters probably have welders as well. The frame is designed to be exceptionally strong and includes curved slats which add to the strength of the table. The table is also designed to be portable, so the curved slats stay in place when the table is moved.

While this might seem like an average metal table at first glance, the table is actually being designed with a homemade CNC machine in mind which [Daniel] is working on. The CNC plasma cutter needs a sturdy, flat surface and can’t be set up on bricks in the driveway, so this table suits both [Daniel]’s immediate needs to not shower himself in sparks every time he cuts something and also his future CNC machine’s need for a sturdy, flat workspace. We look forward to seeing that build being completed but in the meantime take a look at this motorized plasma cutter which has the beginnings of a CNC machine if in one direction only.

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File testing rig

Science Vs Internet Trolls: Testing Another Kind Of File System

No matter what you do or say on the Internet, you’re always doing it wrong. Keyboard commandos are ready to pounce and tell you how it’s “ackchyually” supposed to be done. And so it was of little surprise when [Jason] of Fireball Tools was taken to task by the armchair millwright for his supposedly deficient method of filing metal.

But [Jason] chose to fight back not with words but deeds, building a system to test alternative methods of filing. His filing style is to leave the file in contact with the stock on both the front- and back-strokes, which enraged those who claim that a file must never be dragged back over the workpiece, lest the teeth become dull. The first video below shows the build of the test rig, which leveraged his enormous Cinncinatti shaper as the prime mover, as well as a pneumatic jig to hold the workpiece and imitate both styles of filing. Part two below shows the test rig in action, and [Jason] really outdoes himself with his experimental approach. He tested three different grades of Pferd files — nothing but the best, no expense spared — and did duplicates of each run using both the Internet-approved style and his lazier style.

The result? We won’t spoil that for you, but suffice it to say that the hive mind isn’t always right. And what’s more, [Jason]’s careful myth-busting yielded a few interesting and unexpected results. His channel is full of great shop tips and interesting builds, so check him out if you want to see how metalworking is done.

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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.

How To Get Good With Wood

It’s perhaps unsurprising that we don’t see much in the way of woodworking here at Hackaday; after all, this is a plastics and metal community if there ever was one. But that doesn’t mean you’ll never come across a situation where a dead tree needs to be cut or shaped to your will, so we appreciate [Eric Strebel] demonstrating some tips and best practices for working with this exceptionally versatile building material.

The first video assumes you’re a lumber neophyte, and goes over topics such as the different species of wood you’re likely to find at the hobby shop, proper sanding technique, and the differences between cutting with and against the grain. Some of the different cutting tools you can use are also covered, ranging from the humble hobby knife to the band saw. As always, [Eric] sprinkles the video with tips and tricks gained from his considerable professional experience, such as using some glue and a bit of sawdust to fill in any gaps left behind by an uneven joint.

In the second video, things start getting more advanced. [Eric] demonstrates how you can create custom laminates, and how wood can be permanently bent into arbitrary shapes with sufficient steam and clamping pressure. By combining these new techniques with the basic concepts covered in the first video, surprisingly complex shapes can be formed with minimal effort.

[Eric] previously put together a similar series of videos on working with acrylic, a material that’s arguably far more familiar to the Hackaday readership. But whatever material you use, the takeaway message from this series is clear: get the right tools, learn the techniques, and professional results are well within your reach.

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Building A Stump Grinder From The Ground Up

Felling a tree properly is a skill that takes some practice to master, especially without causing any injuries or property damage. Getting the tree cut down though is sometimes only half of the battle, as the stump and roots need to be addressed as well. Unless you have a few years to wait for them to naturally decompose you might want to employ a stump grinder, and unless you want to spend a chunk of money on a stump grinding service or buy your own, you might want to do what [Workshop from Scratch] did and build your own.

This stump grinder isn’t anything to scoff at, either, and might even fool some into thinking it’s a consumer grade tool from a big box store. Far from it though, as almost everything down to the frame is custom machined specifically for this build. The only thing that isn’t built from scratch, including the cutting wheel, is the beefy 15 horsepower motor. Once it gets going it is able to carve stumps down to the ground in no time thanks especially to some gear reductions in the drive line from the motor to the cutting head.

Before anyone mentions safety, it looks like [Workshop from Scratch] has made some upgrades since his last project which was a gas-powered metal cutting chainsaw. Since then it looks like he has upgraded the sheet metal to something a little thicker, even though a stump grinder has arguably lower risk due to the slower speed of the cutting wheel and also to the fact that the cutting medium is wood and not metal. There are also brakes and an emergency shutoff switch. It sure seems like a fine addition to his collection of completely custom tools.

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