Keep Scraps Around

When I’m building something, I like to have a decent-sized scrap pile on hand. Because when I’ve got to test something out — does this glue adhere to this fabric, how much force will this hold if I tap it and put a screw in, will it snap if reinforced with carbon fiber and epoxy — it’s nice to have some of the material in question on hand just for experimentation. So I pull a chunk out of the scrap pile!

But scrap piles can’t expand forever, and we all know that “too much of a good thing” is a thing, right? Scrap piles require constant pruning. You don’t really need more than a few aluminum extrusion cutoffs, so when you start building up excess inventory, it’s time to scrap it. I mean, throw it away.

A corollary of this, that I’ve only recently started to appreciate, is that if I limit the number of materials that I’m working with, it’s a lot more manageable to keep the scrap pile(s) under control. It’s simple math. If I’m working with twenty different materials, that’s twenty different heaps of scrap. But if I can get by with one weight of fiberglass for everything, that one pile of scraps can do double or triple duty. There is also the added benefit that I already know how the material works, and maybe even have old test samples on hand.

Indeed, I’m such a scrapaholic that it’s almost painful to start working with a new material and not have a scrap pile built up yet. I’m always loathe to cut into a nice square piece of stock just to test something out. But this too is part of the Great Circle of Life. By not testing things out beforehand, I’m almost guaranteed to screw up and create scrap out of what I had hoped was going to be a finished piece. See? No problem! Next version.

What do you think? Are scrap, offcuts, and their close cousins — test pieces and samples — worth keeping around in your shop? Do you have a disciplined approach, or do you just throw them in the corner? Purge per project, or only when the mountain of XPS foam gets as high as your head?

3D-Printed, Hot-Swap Keyboard PCB Generator Is Super Cool

About a month ago, [50an6xy06r6n] shared their hot swap 3D-printed circuit board for keyboard design with the mechanical keyboard subreddit. It’s more of a prototyping tool than a permanent fixture, though nothing is stopping you from using it permanently. Well, now it’s even better, and open source to boot.

[50an6xy06r6n] came up with this to test split ergo layouts faster and not have to solder anything — the switch pins make contact with the row wires and folded diode legs. In fact, prepping all the diodes is probably the thing that takes the longest.

The design can be generated from layout data, or you can convert directly from a KLE JSON file. We love how delightfully clean this keyboard breadboard generator looks, and we wish we had thought of it!

[50an6xy06r6n]’s PCB generator currently supports Cherry MX/clones and Kailh Choc switch footprints. If you want ALPS, somebody’s gonna have to send [50an6xy06r6n] some ALPS to make that happen.

As long as all the contact points are good, you should be able to use this as the final PCB indefinitely. We’ve certainly seen our share of 3D-printed wire guides. Really, you could print the whole thing, including the switches.

Flexible Prototyping For E-Textiles That Doesn’t Cost An Arm And A Leg

Let’s face it: pretty much everything about e-textiles is fiddly. If wearables were easy, more people would probably work in that space. But whereas most circuit prototyping is done in two dimensions, the prototyping of wearables requires thinking and planning in 3D. On top of that, you have to figure out how much conductive thread you need, and that stuff’s not cheap.

[alch_emist] has a method for arranging circuits in 3D space that addresses the harsh realities of trying to prototype wearables. There’s that whole gravity thing to deal with, and then of course there are no straight lines anywhere on the human body. So here’s how it works: [alch_emist] made a bunch of reusable tie points designed to work with an adhesive substrate such as felt. They laser-cut a set of acrylic squares and drilled a hole in each one to accommodate a neodymium magnet. On the back of each square is a small piece of the hook side of hook-and-loop tape, which makes the tie points stay put on the felt, but rearrange easily.

We love the idea of prototyping with felt because it’s such a cheap and versatile fabric, and because you can easily wrap it around your arm or leg and see how the circuit will move when you do.

Not quite to this planning stage of your next wearable project? Magnets and conductive thread play just as well together in 2D.

Brilliant Brick Prototyping

Have a rusty collection of protoboards wired together that would benefit from mechanical support? Working on putting together a robot and need to attach PCBAs without drilling holes, zipping a cable tie, or globing hot glue? Add some stud holes with [James Munns]’ Brick Mount! This isn’t the first time we’ve seen an interface between everyone’s favorite Nordic building system and circuitboards, but this implementation has the elegance we’ve come to expect from [James]’ software work.

4×8 Feather Medium protoboard

The project repository contains two things: a KiCad library with components for holes in standard patterns and sizes (1×1, 1×2, etc) and a series of protoboards made with those hole components. The protoboards feature a couple common elements; QUIIC connectors for easy chaining between them and holes in the middle or edges for easy mounting on studs. Some are intended to be carriers for Feather-format PCBAs (very convenient!) and others are primarily undifferentiated prototyping space. Of particular note is the “medium” Feather breakout seen to the left, which incorporates clever cutouts to make it easy to wires down under the board so it can be mounted flush against another board.

The thesis here is that getting custom PCBs fabricated is easier and less expensive than ever before. So easy and inexpensive that fabricating customized protoboard to use in one-off projects is cost-efficient enough to be worthwhile. Waste concerns aside this does seem like a great way to level up those temporary projects which find a more permanent home.

HackadayU Announces Rhino, Mech Eng, And AVR Classes During Winter Session

The winter lineup of HackadayU courses has just been announced, get your tickets now!

Spend those indoor hours leveling up your skills — on offer are classes to learn how to prototype like a mechanical engineer, how to create precision 3D models in Rhino, or how to dive through abstraction for total control of AVR microcontrollers. Each course is led by an expert instructor over five classes held live via weekly video chats, plus a set of office hours for further interaction.

  • Introduction to 3D using Rhino
    • Instructor: James McBennett
    • Course overview: Introduces students to Rhino3D, a NURBS based 3D software that contains a little of everything, making it James’ favorite software to introduce students to 3D. Classes are on Tuesdays at 6pm EST beginning January 26th
  • Prototyping in Mechanical Engineering
    • Instructor: Will Fischer
    • Course overview: The tips and tricks from years of prototyping and mechanical system design will help you learn to think about the world as a mechanical engineer does. Classes are on Tuesdays at 1pm EST beginning January 26th
  • AVR: Architecture, Assembly, & Reverse Engineering
    • Instructor: Uri Shaked
    • Course overview: Explore the internals of AVR architecture; reverse engineer the code generated by the compiler, learn the AVR assembly language, and look at the different peripherals and the registers that control their behavior. Classes are on Wednesdays at 2pm EST beginning January 27th

Consider becoming an Engineering Liaison for HackadayU. These volunteers help keep the class humming along for the best experience for students and instructors alike. Liaison applications are now open.

HackadayU courses are “pay-as-you-wish” with a $10 suggested donation; all proceeds go to charity with 2019 contributions topping $10,100 going to STEAM:CODERS. There is a $1 minimum to help ensure the live seats don’t go to waste. Intro videos for each course from the instructors themselves are found below, and don’t forget to check out the excellent HackadayU courses from 2020.

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Hack A Folding Bike To Help You Catch Some Pike

For many of us, this whole pandemic thing has produced some unexpected upsides. One of [George Turvey]’s was finding a nice new scenic route to work that goes by a lake with bike trails. [George] thought it might be nice to go fishing after work, and use a folding bike to cover a lot of ground while looking for good spots on the shore. There was just one problem — riding a bike while transporting tackle is awkward.

The bike comes with a front mount that’s meant to hold the special bags they make, so that became square one for designing a rod and tackle holder. Then [George] had to weigh the pros and cons of additive vs. subtractive methods for prototyping the holder, or at least the connection between it and the mount on the bike.

Milling won out, at least for the initial proof of concept, and result is a modular mock-up that combines a milled Kydex connector and tackle box holder with a double-barrel PVC rod holder. This way, [George] had a prototype in a fraction of the time it would have taken to design and print it. Cast your line past the break to see how fast [George] can switch gears into fishing mode.

3D printing definitely has a place in the fishing world. How else are you gonna design your own lures?

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Fewer Millimeters Make A Useful ESP32 Devboard

Sometimes the most useful hacks aren’t the flashiest, they’re the ones that improve an already great tool and make something better. Through hole components are still the fastest and perhaps most satisfying way to prototype a new electronics project so it’s extra frustrating when the happy hacker discovers their new devboard is too wide to fit in a standard breadboard. [Tobias] had the same thought and redesigned the standard ESP32 “NodeMCU” style devboard to be almost exactly the same, but narrower.

Interactive BOMs make assembly a snap

Not to trivialize, but that’s pretty much it. And we love it! The new design retains the great support of the original devboard but adds a few nice tweaks. Obviously there’s the small size change that allows it to fit on a standard 5×5 breadboard leaving sockets available on either side for interfacing. Even in this smaller size [Tobias] managed to retain the boot mode and reset buttons though the overall pinout has changed slightly. And for easier connections ye olde micro USB socket has been swapped for sleek modern USB-C. You have cables for that common standard now, right?

How do you get one? As far as we know [Tobias] isn’t selling these but the design is completely open source and the design, fab, and BOM files are all in the github repository. [Tobias] even went so far as to include the extremely handy interactive BOM to speed up hand assembly. The real trick here is that the board is designed to facilitate the extremely inexpensive turnkey assembly now available from our favorite fab houses, with an example cost of $8/piece for a run of five. The repo includes a properly formatted BOM and fab files to make ordering them a snap. See the bottom of the README for details about what to order.