Linux Fu: Deep Git Rebasing

If you spend much time helping people with word processor programs, you’ll find that many people don’t really use much of the product. They type, change fonts, save, and print. But cross-references? Indexing? Largely, those parts of the program go unused. I’ve noticed the same thing with Git. We all use it constantly. But do we? You clone a repo. Work on it. Maybe switch branches and create a pull request. That’s about 80% of what you want to do under normal circumstances. But what if you want to do something out of the ordinary? Git is very flexible, but you do have to know the magic incantations.

For example, suppose you mess up a commit message — we never do that, of course, but just pretend. Or you accidentally added a file you didn’t want in the commit. Git has some very useful ways to deal with situations like this, especially the interactive rebase.

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Share Your Projects: Making Helpful PCBs

When it comes to things that hackers build, PCBs are a sizeable portion of our creative output. It’s no wonder – PCB design is a powerful way to participate in the hardware world, making your ideas all that more tangible with help of a friendly PCB fab. It’s often even more lovely when the PCB has been designed for you, and all you have to do is press “send” – bonus points if you can make a few changes for your own liking!

A lot of the time, our projects are untrodden ground, however, and a new design needs to be born. We pick out connectors, work through mechanical dimensions, figure out a schematic and check it with others, get the layout done, and look at it a few more times before sending it out for production. For a basic PCB, that is enough – but of course, it’s no fun to stop at ‘basic’, when there’s so many things you can do at hardly any cost.

Let’s step back a bit – you’ve just designed a board, and it’s great! It has all the chips and the connectors you could need, and theoretically, it’s even supposed to work first try. Now, let’s be fair, there’s an undeniable tendency – the more PCBs you design, the better each next one turns out, and you learn to spend less time on each board too. As someone with over two hundred PCBs under her belt, I’d like to show you a bunch of shortcuts that make your PCB more helpful, to yourself and others.

There’s a few ways that you can share your PCB projects in a more powerful way – I’d like to point out a few low-hanging fruits, whether README.md files or markings on the PCB itself. I’ve been experimenting quite a bit with external and embedded documentation of PCBs, as well as PCB sharing methods, got some fun results, and I’d like to share my toolkit through a few punchy examples and simple tricks. I’d also like to hear about yours – let’s chat! Continue reading “Share Your Projects: Making Helpful PCBs”

[Ben Eater]’s Breadboarding Tips

A solderless breadboard is a place where ideas go to become real for the first time. Usually, this is a somewhat messy affair, with random jumpers flying all about the place, connecting components that can be quickly swapped to zero in on the right values, or to quickly change the circuit topology. Breadboards aren’t the place to make circuit artwork.

That is, however, not always the case, and we’ve seen more than a few examples from [Ben Eater] on breadboarding that approaches the circuit sculpture level of craftsmanship. And like any good craftsman, [Ben] has shared some of his breadboarding tips and tricks in a new video. Starting with a simple 555 blinkenlight project that’s wired up in the traditional anything-goes fashion, [Ben] walks us through his process for making a more presentation-worthy version.

His tools are high-quality but simple, with the wire strippers being the most crucial to good results. Surprisingly, [Ben] relies most heavily on the simple “scissors-style” strippers for their versatility, rather than the complicated semi-automatic tools. We found that to be the biggest take-home from the video, as well as the results of practice. [Ben] has done tons of this type of breadboarding before, which means when he “eyeballs” stripping 0.3 inches of insulation, he can do it down to a ten-thousandth precision.

Granted, there’s not much new here, but watching this video is a little like watching [Bob Ross] paint — relaxing and strangely compelling at the same time. You can get more of the same with pretty much any of his videos that we’ve covered, like this 6502 breadboard computer build. We’ve also seen [Eater]-inspired builds that are pretty impressive, like this full-8-bit breadboard computer.

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DIY Cable Chain Looks Great, Stays Cheap

If you’ve built a 3D printer, CNC, laser cutter, or basically any piece of electrical equipment that moves around, then you’ve run into the problem of securing the bundle of wires that such machines always require. The easy way out is to zip tie them all up into a tight harness or put them in commercially available wraps or sleeves, but these don’t really impart any mechanical strength on the wires. With repetitive motion it’s not unheard of to break a conductor or two, causing intermittent failures and generally leading to a painful diagnostic session trying to isolate the broken wire.

An alternative are what are generally referred to as “cable chains”. These are rigid enclosures for your wiring that not only keep things tidy, but give the wires the mechanical support necessary to prevent fatigue. Unfortunately, they are often many times more expensive than a simple wire wrap or pack of zip ties. But [Brad Parcels] has written into our tip line to share with us a sort of hybrid approach to wire management that has many of the same advantages as a traditional cable chain, but at a greatly reduced cost.

The key to the design is using the metallic tape from a cheap tape measure to give the bundle of wires some mechanical strength. As anyone who’s ever played around with a tape measure knows, if you bend the tape over into a U shape it will hold the bend even if you extend and retract it. Thanks to this principle, [Brad] realized that all he need to do was add some wire sleeves and he would have a cheap and effective way to keep his wiring neat and sag-free.

[Brad] punches holes in the tape to secure it to his 3D printed mounting arms, but really any method of securing the tape to the frame of your machine will work just as well. He then slides a cable sleeve over the tape itself to protect from any possibility of the edge of the tape nicking a wire, and then finally a larger wire sleeve over the entire assembly.

After running the wires between the two sleeves, heatshrink can be used on the ends to neatly close everything up. Just make sure you remember all your wires before you seal it, [Brad] learned that one the hard way. But overall, he reports this DIY cable chain arrangement has been working wonderfully in his machine, providing smooth and silent movement for only a few bucks.

Cable management for projects that move is one of those things that doesn’t always get the attention it deserves. Not only can it keep your project looking professional, but it just might save you some time down the road by preventing failures.

Tips For Basic Machining On A Drill Press

It’s safe to say most Hackaday readers would love to have a mill at home, or a nice lathe, but such equipment isn’t always practical for the hobbyist. The expense and amount of room they take up is a hard sell unless you’re building things on them regularly, so we’re often forced to improvise. In his latest video, [Eric Strebel] gives some practical advice on using a standard drill press to perform tasks you would normally need a mill or lathe for; and while his tips probably won’t come as a surprise to the old-hands out there, they might just help some of the newer players get the most out of what they have access to.

[Eric] explains the concept of the cross slide vice, which is the piece of equipment that makes machining on a drill press possible. Essentially it’s a standard vice, but with screws that allow you to move the clamped piece in the X and Y dimensions under the drill which can already move in the Z dimension. For those counting along at home, that puts us up to the full three dimensions; in other words, you can not only make cuts of varying depths, but move the cut along the surface of the work piece in any direction.

You can even turn down a (small) piece of round stock by placing it in the chuck of the drill press, and putting a good chisel in the cross slide vice. The chisel can then be moved up against the spinning piece to make your cuts. We don’t suggest doing anything too heavy, but if you need to turn down something soft like a piece of plastic or wood to a certain diameter, it can do in a pinch.

[Eric Strebel] is quickly becoming a favorite around these parts. His well-produced videos show viewers the practical side of product design and in-house manufacturing. We recently covered his video on doing small-scale production, and there’s plenty more invaluable info to be had browsing back through his older videos.

The quest to do machining without actually having a machine shop is certainly not new to Hackaday. There have been many different approaches to solving the issue, but picking up a decent drill press and cross slide is a first step down the rabbit hole for most people.

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Go From Resin Caster To Resin Master

When it comes to resin casting, time is of the essence. It helps to gather everything you’ll need and have it within reach before starting. But if you don’t know what you don’t know, it can be difficult to anticipate needs. Luckily, [Botzen Design] has a few tricks up his sleeve that will save time, materials, and sanity for novices and old hands alike.

It may seem somewhat obvious to mix up resin in a disposable or reusable plastic cup. But not all cups are created equal. Polypropylene cups won’t outgas into your resin, but polystyrene will. If you use a silicone cup or any polypropylene food container marked #5/PP, cured resin will peel cleanly off of the cup walls.

For some reason, the giant jugs of resin [Botzen Design] uses don’t come with pumps. How do they expect someone to meter out exact amounts of resin and hardener while pouring them out of gallon jugs? Stadium-style condiment pumps at a restaurant supply store make things much simpler while avoiding costly spillage.

Our favorite tip (and seemingly [Botzen Design]’s as well) is the drip hammer. When air bubbles mature into craters, they can be filled easily and precisely with a drop or two of wet resin. A pipette would probably just get clogged, but an icicle of cured resin hanging from a stick makes the perfect drip applicator.

Want to get into resin casting but don’t know where to start? Hackaday’s own [Gerrit] has you more than covered.

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Sacrificial Bridge Avoids 3D Printed Supports

[Tommy] shares a simple 3D printing design tip that will be self-evident to some, but a bit of a revelation to others: the concept of a sacrificial bridge to avoid awkward support structures. In the picture shown, the black 3D print has small bridges and each bridge has a hole. The purpose of these bits is to hold a hex nut captive in the area under the bridge; a bolt goes in through the round hole in the top.

Readers familiar with 3D printing will see right away that printing the bridges might be a problem. When a printer gets to the first layer of the bridge, it will be trying to lay filament in empty space. By itself this is not usually a problem as long as a bridge is short, flat, and featureless. Unfortunately this bridge has a hole in it, and that hole means the printer will be trying to draw circles in mid-air, rather than simply stretching filament point-to-point across a gap. One solution would be to add a small amount of support structure, but that just moves the problem. Removing small supports from enclosed spaces can be a real hassle.

To solve this [Tommy] added what he calls a “sacrificial bridge”, shown as blue in the CAD image. He essentially gives the hole a flat bottom, so that the printer first lays down a thin but solid bridge as a foundation. Then, the portion with the round hole is printed on top of that. With this small design change, the print becomes much more reliable with no support structure required.

There is a bit of post-work involved since each hole needs to be drilled out to punch through the thin sacrificial bridge underneath, but it definitely beats digging out little bits of support structure instead.