Beginning The Machine Shop Journey With A DIY CNC

Building a good quality machine shop may seem to present a chicken-and-egg problem, at least for anyone not willing to mortgage their home for the money needed to buy all of these tools new. Namely, that building good tools often requires good tools. To help solve this problem, [Ryan] designed and built this CNC machine which can be built with nothing other than common tools, hardware store supplies, and some readily available parts from the internet.

Since it’s being built from consumer-grade material, [Ryan] has the design philosophy of “buying precision” which means that most of the parts needed for this build are precise enough for their purpose without needing to be worked in any way before incorporation into the mill. For example, he uses a granite plate because it’s hard, flat, heavy, and sturdy enough at the time of purchase to be placed into the machine right away. Similarly, his linear guides do not need to be modified before being put to work with a high degree of precision and minimal calibration. From there, he applies the KISS principle and uses the simplest parts available. With this design process he is able to “bootstrap” a high quality mill for around $1500 USD without needing any extra tools than the ones you likely already have.

The RIG-CNC as it is known has also been made completely open source which further cements its bootstrapability, and there is a lot more detail on the project page and in the video linked below. This project is unique not simply for the mill build from common parts and tools, but because this design philosophy is so robust. Good design goes a lot farther in our builds than a lot of us might realize, and good design often results in more maintainable, hackable things that work for more uses than the original creators may have even thought about.

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Retrotechtacular: Discovering Aerodynamics With The Chrysler Airflow

When you think about it, for most of human history we’ve been a pretty slow bunch. At any time before about 150 years ago, if you were moving faster than a horse can run, you were probably falling to your death. And so the need to take aerodynamics into consideration is a pretty new thing.

The relative novelty of aerodynamic design struck us pretty hard when we stumbled across this mid-1930s film about getting better performance from cars. It was produced for the Chrysler Sales Corporation and featured the innovative design of the 1934 Chrysler Airflow. The film’s narration makes it clear why the carmaker would go through the trouble of completely rethinking how cars are made; despite doubling average engine horsepower over the preceding decade, cars had added only about 15% to their top speed. And while to our 21st-century eyes, the Chrysler Airflow might look like a bulked-up Volkswagen Beetle, compared to the standard automotive designs of the day, it was a huge aerodynamic leap forward. This makes sense with what else was going on in the technology world at the time — air travel — the innovations of which, such as wind tunnel testing of models, were spilling over into other areas of design. There’s also the influence of [Orville Wright], who was called in to consult on the Airflow design.

While the Airflow wasn’t exactly a huge hit with the motoring public — not that many were built, and very few remain today; [Jay Leno] is one of the few owners, because of course he is — it set standards that would influence automotive designs for the next 80 years. It’s fascinating too that something seemingly as simple as moving the engine forward and streamlining the body a bit took so long to hit upon, and yet yielded so much bang for the buck.

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Design An Electronic Catan Board In A Day

One of the things that makers sometimes skip over is the design of the project that they’re creating. Some of us don’t do any design at all, we just pants it. The design part of making something can take quite a while – there is sketching to do, as well as 3d-modelling and PCB creation. [Sam March] wanted to try and create something interesting where he did the design in a single day. The result is, or will be, a 3D printed, electronic, Settlers of Catan game board.

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Balanced Design And How To Know When To Quit Optimizing

I got a relatively inexpensive 6040 CNC machine, and have been spending most weekends making the thing work, and then cutting stuff, learning the toolchain, and making subsequent improvements. Probably 90% of my machine time has been on making improvements. It’s not that the machine was bad — I got the version with ballscrews and a decently solid frame — but it’s that it somehow didn’t work together as a whole. It’s just an incredibly unbalanced design.

Let’s start with the spindle motor. It’s a 2.2 kW water-cooled beast that is capable of putting tons of work into a piece and spinning at very high speed. Yet to keep up with the high speed spindle, the motors that move it around would have to be capable of high speeds as well — it’s a feeds and speeds thing if you’re not a CNC geek. And they can’t. Instead, the stepper motors that came with the kit are designed for maximum force at low speeds. Which can make sense for some machines, but for one with a slightly flexible X-axis like this one, that’s wasted as well. The frame just can’t handle the low-end grunt that the motors are capable of, so it can’t take advantage of the spindle’s power either. The design is all over the place.

Over the last two months’ of weekends, I’ve been going through this iterative procedure of asking “what is my limiting factor right now?”, working on fixing that thing up, running it some, and then asking the question again. And it’s a good general procedure, and I believe that it’s getting me to the machine I want at the minimum cost of time, money, and effort.

At first, it was the driver hardware/software with its emulated USB parallel port, so I swapped out the controller for an Arduino running GRBL, soldered directly to the DB-25 that comes out of the back. At least it can put out pulses fast enough to order the motors around, but they would still stall out at high speeds. Swapping the stepper motors out for a high-speed pair only cost me €40, which makes you wonder why they didn’t just put the right motors on in the first place. The machine now travels fast enough to make use of the high-speed spindle, and I’m flying through plywood and plastics without leaving burn marks. It’s a huge win for not much money.

The final frontier is taking big bites out of aluminum. The spindle can do it, but I fear I’m up against the frame’s rigidity on the X-axis. For whatever reason, they went with unsupported rods on the X, which are significantly more flexible than an axis that’s backed up by more metal. And this is where the limiting factor may actually be my time and patience, rather than money. I just can’t bear to disassemble and reassemble the thing again. So for now, it’s going to be small nibbles, taking advantage of the machine’s speed, if not yet the spindle’s full horsepower.

But it’s odd, because this machine is a bundle of good parts. It’s just that they haven’t been chosen to work together optimally; the frame doesn’t work with the stepper motors, which don’t work with the spindle. If they went through my procedure of saying “what’s the limiting factor?” they could have saved themselves €100 by just shipping it with a wimpier spindle, which would have been a balanced, if anemic, machine. Or they could have built it with the right motors for more speed. Or supported rails for more grunt. Or both!

I’ll never know why they quit optimizing their design when they did. Maybe they never got past the slow USB/parallel port speed? But I’m near the end of my path, and I can tell because the limiting ingredient isn’t a simple upgrade, or even mere money anymore, but my own willpower.

How can you tell when you’re at the top of a mountain in a dense fog? A step you take in any direction would lead you downhill. How can you tell when you’re satisfied with a project’s state? When you don’t have the need, or desire, to undertake the next most obvious improvement.

Free To Good Home: FPGA Supercharged Audio/Video Synthesizer

Audio and video synthesizers have been around for decades, and are pretty much only limited by one’s willingness to spend money on them.  That is, unless you can develop your own FPGA-supercharged synthesizer to really get a leg up on the consumer-grade components. Of course, as [Julian] found out in this four-year project, you tend to pay for it anyway in time spent working on your projects.

[Julian] has actually decided to stop working on the project and open-source it to anyone who wants to continue on. He has already finished the PCB layout on a gargantuan 8-layer print, done all of the routing and parts selection, and really only needed to finish testing it to complete the project. It’s powered by the Xilinx Zynq and is packed with features too: HDMI, DDR3 ram, USB, a handful of sensors, and an Arduino Uno-style header to make interfacing and programming a breeze.

While we’re sympathetic with setting aside a project that we’ve worked so hard on, with most of the work done on this one it should be pretty easy to pick up and adapt for anyone interested in carrying the torch. If you were hoping to wet your whistle with something with fewer PCB layers, though, we’ve seen some interesting (but slightly simpler) video synthesizers made out of other unique hardware as well.


The Right Tools For The Job

We’re knee-deep in new microcontrollers over here, from the new Raspberry Pi Pico to an engineering sample from Espressif that’s right now on our desk. (Spoiler alert, review coming out Monday.) And microcontroller peripherals are a little bit like Pokemon — you’ve just got to catch them all. If a microcontroller doesn’t have 23 UARTS, WiFi, Bluetooth, IR/DA, and a 16-channel 48 MHz ADC, it’s hardly worth considering. More is always better, right?

No, it’s not. Chip design is always a compromise, and who says you’re limited to one microcontroller per project anyway? [Francesco] built a gas-meter reader that reminded to think outside of the single-microcontroller design paradigm. It uses an ATtiny13 for its low power sleep mode, ease of wakeup, and decent ADCs. Pairing this with an ESP8266 that’s turned off except when the ATtiny wants to send data to the network results in a lower power budget than would be achievable with the ESP alone, but still gets his data up into his home-grown cloud.

Of course, there’s more complexity here than a single-micro solution, but the I2C lines between the two chips actually form a natural division of work — each unit can be tested separately. And it’s using each chip for what it’s best at: simple, low-power tasks for the Tiny and wrangling WiFi on the ESP.

Once you’ve moved past the “more is better” mindset, you’ll start to make a mental map of which chips are best for what. The obvious next step is combination designs like this one.

Run The Math, Or Try It Out?

I was reading Joshua Vasquez’s marvelous piece on the capstan equation this week. It’s a short, practical introduction to a single equation that, unless you’re doing something very strange, covers everything you need to know about friction when designing something with a rope or a cable that has to turn a corner or navigate a wiggle. Think of a bike cable or, in Joshua’s case, a moveable dragon-head Chomper. Turns out, there’s math for that! Continue reading “Run The Math, Or Try It Out?”