How Art Became Science In Machining

Machining is one of those fascinating fields that bridges the pre-scientific and scientific eras. As such, it has gone from a discipline full of home-spun acquired wisdom and crusty old superstitions to one of rigorously analyzed physics and crusty old superstitions.

The earliest machinists figured out most of what you need to know just by jamming a tool bit into spinning stock and seeing what happens. Change a few things, and see what happens next. There is a kind of informal experimentation taking place here. People are gradually controlling for variables and getting better at the craft as they learn what seems to affect what. However, the difference between fumbling around and actually knowing something is controlling for one’s own biases in a reproducible and falsifiable way. It’s the only way to know for sure what is true, and we call this “science”. It also means being willing to let go of ideas you had because the double-blinded evidence clearly says they are wrong.

That last part is where human nature lets us down the most. We really want to believe things that confirm our preconceived notions about the world, justify our emotions, or make us feel better. The funny thing about science, though, is that it doesn’t care whether you believe in it or not. So go get your kids vaccinated, and up your machining game with scientific precision. Let’s take a look.

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Hack Chat: The Home Machine Shop with Quinn Dunki

Join us Wednesday at noon Pacific time for the Home Machine Shop Hack Chat!

Even if you haven’t been here for very long, you’ll probably recognize Quinn Dunki as Hackaday’s resident consulting machinist. Quinn recently did a great series of articles on the “King of Machine Tools”, the lathe, covering everything from the history of precision machine tools to making your first chips. She’s documented the entire process of procuring and setting up a new lathe, pointing out all the potential pitfalls the budding home machinist may face. You can get a much deeper dive into her machining adventures on her YouTube channel, Blondihacks.

Flinging hot metal chips around is hardly all Quinn has accomplished, though. Long before her foray into machine tools, there was Veronica, a scratch-built 6502 machine Quinn created as an homage to the machines that launched her into a life of writing software. We’ve featured Veronica on our pages a couple of times, and she’s always made quite a hit.

Please join us for this Hack Chat, where we’ll discuss:

  • How developing software and machining are alike, and how they differ;
  • How social networks have changed the perception of machining;
  • Best practices for getting started in machining; and
  • Are there any new machine tool purchases in the pipeline?

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Home Machine Shop Hack Chat and we’ll put that in the queue for the Hack Chat discussion.

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, March 20, at noon, Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Already Impressive CNC Router Gets An Extra Axis

The type of CNC machine within the financial reach of most DIYers is generally a three-axis affair, with a modest work envelope and a spindle that never quite seems powerful enough. That’s not to say that we don’t covet such a machine for our own shop of course, but comparing small machines with the “big boy” five-axis tools might leave the home-gamer feeling a tad inadequate.

Luckily, there’s a fix that won’t necessarily break the bank: adding a fourth axis to your CNC router. [This Old Tony] tore into his CNC router – a build we’ve featured before and greatly admire – to add a machine spindle that lets him work with the machine much as if it was a CNC lathe. The first video below covers the mechanical part of the build, which involves welding and machining a sturdy assembly to hold a spindle connecting a four-jaw chuck to a Lexium MDrive, a stepper motor with integrated driver and feedback that makes it act more like a servo. [Old Tony] covered integrating the drive into Mach4 in a previous video.

The assembled machine spindle is a beefy looking affair that can smoothly ramp up to 3000 rpm and has decent enough holding torque to allow it to act as an indexing head in addition to a lathe. The second video below shows some tests turning aluminum and steel; we were surprised by how aggressive the cuts can be before stalling the spindle.

No, it’s not a Tormach or Haas or even a Pocket NC, but it’s a great addition to an already capable machine, and we’re looking forward to what [Old Tony] cranks out with it.

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Lathe Headstock Alignment: Cutting A Test Bar

Let’s say you’ve recently bought a lathe and set it up in your shop. Maybe you’ve even gone and leveled it like a boss. You’re ready to make chips, right? Well, not so fast. As real machinists will tell you, you can use all the levels and lasers and whatever that you want, but the proof is in the cut. Precision leveling gets your machine in the ballpark (machinists have very small ballparks) but the final step to getting a machine to truly perform well is to cut a test bar. This is a surefire way to eliminate any last traces of twist in the bed.

There are two types of test bars. One is for checking headstock-to-ways alignment, which is what we’re doing here. There’s another type used for checking tailstock alignment, but that’s a subject for another day.

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The Machinists’ Mantra: Level Thy Lathe

Let’s say you’ve gone and bought yourself a sweet sweet metal lathe. Maybe it’s one of the new price-conscious Asian models, or maybe it’s a lovely old cast iron beast that you found behind a foreclosed machine shop. You followed all the advice for setting it up, and now you’re ready to make chips, right? Well, not so fast. Unlike other big power tools, such as band saws or whatever people use to modify dead trees, machine tools need to be properly level. Not, “Hurr hurr my carpenter’s level says the bubble is in the middle”, but like really level.

This is especially true for lathes, but leveling is actually a proxy for something else. What you’re really doing is getting the entire machine in one plane. Leveling is a primitive way of removing twist from the structure. It may not seem like a huge piece of cast iron could possibly twist, but at very small scales it does! Everything is a spring, and imperceptible twist in the machine will show up as your lathe turning a couple thousandths of taper (cone) when it should be making perfect cylinders. All this is to say, before making chips, level your lathe. Let me show you the way. Continue reading “The Machinists’ Mantra: Level Thy Lathe”

Preparing For A Lathe: How to Move 3000 Pounds of Iron

You say to yourself, “Self, I want, nay, need a lathe”. Being a good little trooper, you then did all your research, having chosen Import or American, Imperial or Metric, and all your feed options and such. You then pulled the trigger and the machine is en route to your shop. Now what?

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A Buyer’s Guide to Lathe Options

Lathes are complicated machines, and buying one requires weighing a lot of options. We’ve already talked about buying new Asian, or old American machines (with apologies to the Germans, British, Swiss, and all the other fine 20th century machine tool making-countries). We also talked about bed length and swing, and you ain’t got nothin’ if you ain’t got that swing. Let’s talk about the feature set now. If you’re buying new, you’ll shop on these details. If you’re buying used, knowing the differences will help you pick a good project machine.

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