Machining Without Machines

It’s a luxury to be able to access a modern machine shop, complete with its array of lathes, mills, and presses. These tools are expensive though, and take up a lot of space, so if you want to be able to machine hard or thick metals without an incredible amount of overhead you’ll need a different solution. Luckily you can bypass the machines in some situations and use electricity to do the machining directly.

This project makes use of a process known as electrochemical machining and works on the principle that electricity passed through an electrolyte solution will erode the metal that it comes in contact with. With a well-designed setup, this can be used to precisely machine metal in various ways. For [bob]’s use this was pretty straightforward, since he needed to enlarge an existing hole in a piece of plate steel, so he forced electrolyte through this hole while applying around half an amp of current in order to make this precise “cut” in the metal, avoiding the use of an expensive drill press.

There are some downsides to the use of this process as [bob] notes in his build, namely that any piece of the working material that comes in contact with the electrolyte will be eroded to some extent. This can be mitigated with good design but can easily become impractical. It’s still a good way to avoid the expense of some expensive machining equipment, though, and similar processes can be used for other types of machine work as well.

Arduino Bobbin Winding Machine Is Freaky Fast

One of the worst things about sewing is finding out that your bobbin — that’s the smaller spool that works together with the needle and the larger spool to make a complete stitch — ran out of thread several stitches ago. If you’re lucky, the machine has a viewing window on the bobbin so you can easily tell when it’s getting dangerously close to running out, but many machines (ours included) must be taken halfway apart and the bobbin removed before it can be checked.

Having spare bobbins ready to go is definitely the answer. We would venture to guess that most (if not all) machines have a built-in bobbin winder, but using them involves de-threading the machine and setting it up to wind bobbins instead of sew. If you have a whole lot of sewing to do and can afford it, an automatic bobbin winder is a godsend. If you’re [Mr. Innovative], you build one yourself out of acrylic, aluminium, and Arduinos.

Here’s how it works: load up the clever little acrylic slide with up to twelve empty bobbins, then dial in the speed percentage and press the start button. The bobbins load one at a time onto a drill chuck that’s on the output shaft of a beefy 775 DC motor. The motor spins ridiculously fast, loading up the bobbin in a few seconds. Then the bobbin falls down a ramp and into a rack, and the thread is severed by a piece of nichrome wire.

An important part of winding bobbins is making sure the thread stays in place at the start of the wind. We love the way [Mr. Innovative] handled this part of the problem — a little foam doughnut around a bearing holds the thread in place just long enough to get the winding started. The schematic, BOM, and CAD files are available if you’d like to make one of these amazing machines for yourself. In the meantime, check out the demo/build video after the break.

Still not convinced that sewing is cool enough to learn? Our own [Jenny List] may be able to convert you. If that doesn’t get you, you might like to know that some sewing machines are hackable — this old girl has a second life as a computerized embroidery machine. If those don’t do it, consider that sewing machines can give you a second life, too.

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Machine Builds Rise From The Ashes

I was enchanted by a failed project this week. [Andrew Consroe]’s CNC scroll saw doesn’t work yet, but the emphasis is on the word “yet”. Heck, even when it does work, it might not make sense, but that’s not the point anyway.

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A scroll saw table has a vertical reciprocating blade perpendicular to a table, a lot like a band saw but with a shorter blade. You push the wood sheet to be cut into the blade, and because it’s thin, you can twist and turn all sorts of interesting jigsaw-puzzle shapes. [Andrew] automated this with an X-Y gantry and an innovative geared rotating ring, needed to keep the wood fed into the cutting edge of the blade.

It’s a crazy contraption, and a difficult and unique movement planning problem, and watching it move in the video is a joy. But it’s not working either: errors in the motion add up over a cut, and he’s ended up snapping a blade on every piece. And this is version three of the device!

But here comes the inspiration. First, the only reason he’s filming this is to keep a log of how the project looked at this phase — he’s already planning out the next one. Second, this is the soul of learning by doing. You don’t learn anything unless you’re trying something new.

And finally, [Andrew]’s project reminds me of why I love machine builds in the age of rapid prototyping. Blazing through three entirely different machines cost him essentially nothing. Tearing apart version one left him with the same stepper motors, aluminum extrusions, and electronics as when he started out. Except that he now knew so much more about his particular problem space. Now he’s ready to go again.

So if you’re at all robotically inclined, but you’re looking at the cost of motors, belts, bearings, and steel, don’t think of it as an expense for this project, but for years’ worth of iterations, and maybe even fully different machines.

Just be sure to take [Andrew]’s lead and get it down and documented before you take it apart! Heck, send it in to Hackaday and it’ll live forever.

This V8 Makes A Shocking Amount Of Power

As a work of art, solenoid engines are an impressive display of electromagnetics in action. There is limited practical use for them though, so usually they are relegated to that realm and remain display pieces. This one from [Emiel] certainly looks like a work of art, too. It has eight solenoids, mimicking the look and internal workings of a traditional V8.

There’s a lot that has to go on to coordinate this many cylinders. Like an internal combustion engine, it takes precise timing in order to make sure that the “pistons” trigger in the correct order without interfering with each other through the shared driveshaft. For that, [Emiel] built two different circuit boards, one to control the firing of each solenoid and another to give positional feedback for the shaft. That’s all put inside a CNC-machined engine block, complete with custom-built connecting rods and shafts.

If you think this looks familiar, it’s because [Emiel] has become somewhat of an expert in the solenoid engine realm. He started off with a how-to for a single piston engine, then stepped it up with a V4 design after that. That leaves us wondering how many pistons the next design will have. Perhaps a solenoid version of the Volkswagen W12?

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Solenoid Engine Adds Three “Pistons”

The earliest piston engines typically had only one cylinder, and at best, produced horsepower measured in single digits. But once you have a working engine, it’s a relatively short step to adding cylinders and increasing the power output. [Emiel] made a similar upgrade to one of his engines recently, upgrading it from one cylinder to four. But this isn’t an internal combustion engine, it gets its power from electric solenoids.

We featured his single-cylinder build about a month ago, and since then he’s been busy with this impressive upgrade. The new engine features four cylinders arranged in a V4 pattern. Of course, this greatly increases the mechanical complexity. To start, he had to machine a crankshaft to connect all four “pistons” to a shared output shaft. He also had to build a set of cams in order to time the firing of the cylinders properly, so they don’t work against one another.

The build is just as polished and impressive as the last, which is saying a lot. [Emiel] has a quality machine shop and built the entire motor from scratch, including winding the solenoids, machining the connecting rods and shafts, and building a very picturesque wooden base for the entire contraption to sit on. It’s definitely worth checking out.

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What Can You Learn From An Eggbot?

An eggbot is probably the easiest introduction to CNC machines that you could possibly hope for, at least in terms of the physical build. But at the same time, an eggbot can let you get your hands dirty with all of the concepts, firmware, and the toolchain that you’d need to take your CNC game to the next level, whatever that’s going to be. So if you’ve been wanting to make any kind of machine where stepper motors move, cut, trace, display, or simply whirl around, you can get a¬†gentle introduction on the cheap with an eggbot.

Did we mention Easter? It’s apparently this weekend. Seasonal projects are the worst for the procrastinator. If you wait until the 31st to start working on your mega-awesome New Year’s Dropping Laser Ball-o-tron 3000, it’s not going to get done by midnight. Or so I’ve heard. And we’re certainly not helping by posting this tutorial so late in the season. Sorry about that. On the other hand, if you start now, you’ll have the world’s most fine-tuned eggbot for 2020. Procrastinate tomorrow!

I had two main goals with this project: getting it done quickly and getting it done easily. That was my best shot at getting it done at all. Secondary goals included making awesome designs, learning some new software toolchains, and doing the whole thing on the cheap. I succeeded on all counts, and that’s why I’m here encouraging you to build one for yourself.

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Lathe’s Tool Holder Holds A Rotary Tool

What is better than a tool? Two. What is better than two? Two tools tooling together. [tintek33] wanted a rotary tool to become an attachment on his mini lathe, the video is also below the break. Fortunately, Dremels and Proxxons are built to receive accessories, or in this case, become one. Even if the exact measurements do not apply to your specific hardware, we get to see the meat of the procedure from concept to use.

We start with where the rotary tool should be and get an idea of what type of bracket will be necessary. The design phase examines the important dimensions with a sketch and then a CAD mock-up. Suitably thick material is selected, and the steps for pulling the tool from the raw stock are shown with enough detail to replicate everything yet there is no wasted time in this video. That is important if you are making a quick decision as to whether or not this is worth your hard work. Once the brace is fully functional and tested, it is anodized for the “summer ocean” blue color to make it easy to spot in the tool heap. Some complex cuts are made and shown close-up.

Thank you [jafinch78] for your comment on Take a Mini Lathe for a Spin and check out [tintek33] using his mini lathe to make a hydraulic cylinder for an RC snow plow.

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