More on Braiding Machines


When I was in high school I got an old singer sewing machine at the goodwill, managed to adjust it until it worked correctly again, and used it for light leather-work. Sewing machines and rope-making machines have a similar problem: you want to get the thread around the bobbin without moving it – which is a really complicated trick since (for the bobbin to be stable) there has to be some kind of supporting thing that holds the bobbin.

braiding machine bobbin race plate

In the case of a rope-making machine, the maximum speed at which you can make rope depends on the speed at which you can reliably move the bobbins in their race. Sewing machines work around that problem because, for machine-sewing, you want it to be very fast (humans who learned how to ply a needle and thread could sew remarkably quickly). If you enjoy mechanical puzzles, I’ll leave it as an exercise (or maybe I’ll do a post) to figure out how Singer’s sewing machines worked. By the way, it took a great deal of effort for Singer to perfect the sewing machine, but it was a world-changing invention at the time; everything prior to Singer was hand-sewn. Everything from sailing ship’s sails to lace doilies – the production rate was limited by the speed of human hands and the number of hands.

Here is a better illustration of how a rope braiding machine works. This is a simple mechanism, for a braiding machine.

The loud “PFFT” sound is the hit/miss engine that is powering it via the chain-drive on the right hand side. By the way, I would never ever ever ever have an exposed chain drive like that anywhere near where a human or a dog or a dancer could get tangled up in it. #SAD.

In the video you can see the circular races that the bobbins walk around; it’s controlled by the meshing of gears under the top plate. You can imagine that the top speed is pretty limited – eventually you’ll have a timing error and one of the gears will bind and then the machine fails. It’s also interesting to look at these early industrial machines and realize that the failure mode is “someone notices something is wrong with the machine” and runs over in time to do something with it. Modern machines take into account the failure modes – something we have learned mostly from our attempts to build computers: think about what’s likely to go wrong, what it looks like when it does, and program the system to do the right thing (usually shut down). So there would be some sort of tension sensor on that chain so that if someone got their hand in it, the extra tension would immediately stop everything. In terms of software, that sort of thing is extra infrastructure that’s “free” (it’s just lines of code) but in a machine, it equates to sensors, more points of failure, increased costs, increased control systems, and more complex and harder to understand failure modes.

Wardwell cam ring machine

There is a second generation rope braider. It’s called a “Wardwell cam ring” and has been evolving since the 1890s; there are still improvements being patented today (still by Wardwell, Inc. Presumably to keep their ownership of the basic design). What I love about this stuff is that techniques in machine design evolve and improve until eventually everyone just says “ah forget it” or there’s a breakthrough and everyone jumps over to the new design. The Wardwell cam ring braiders can do multiple threads in the braid – hence the distinctive metal-braid and carbon fiber braids we began to see in the 90s. The neat part about the Wardwell machine is that it doesn’t move the bobbins between eachother, it moves an inner ring against an outer ring, and the outer ring flips the thread around the inner ring bobbins using a cam. This approach can’t run arbitrarily fast, but it can run a whole lot faster than moving the bobbins around on gears.

Very clever!

I could stare at the patent pictures of that thing for a long time, and I wouldn’t be able to figure it out. It’s still hard – the thread has to go around the inner bobbins, which are supported on a polished disk (you can see them in the center) that the thread spins around – that’s basically Singer’s sewing machine bobbin design, too!

subway stop

the subway station at arts et metiers. Paris FTW.

One of my favorite places when I was a kid was the Musee des Arts Et Metiers (arts and jobs) in Paris. It’s an amazing place that has become a bit less amazing since they pared down the exhibits in the 90s; for most of the industrial age the French patent office required that you submit not just your design, but a working model. The museum used to have models of the evolution of some kind of machine, all laid out, for example a threshing machine, which started as a ground-level cart with a person standing in it with a scythe and a sort of automated rake powered by the forward motion of the horse pulling it – then evolved to an automated rake with a cutting bar, etc. The curator of the museum placed these models in evolutionary sequence so you could see how the clever humans figured out how to take the human out of the loop more and more as the machine evolved. My understanding of evolution comes from machines, not biology: there is just as much interchange of ideas (genetic material) and experiment (survival) as there is in the wild. And commercial success is the decision-maker of reproduction. Designs like Singer’s sewing machine, which are used everywhere, are sort of like the shark of the ocean: so successful there’s not much need to improve any more.

The evolution of rope braiding machines continues, because next they’ll be spinning nanotubes on them. It’ll probably be a design similar to Wardwell’s but eventually maybe there will be linear motion via solenoids.

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Singer sounds like an interesting character. He became very wealthy but was not welcomed into New York’s upper crust, who were mostly the descendants of bankers and real estate speculators and sneered at a machinist. Remember: the Carnegies and Fricks and other industrialists actually didn’t invent their processes (they got their industrial processes the traditional old way: they stole them!) and their money was a whole generation older than Singer’s. Oh, and Singer was jewish. So Singer pretty much said “screw you” and spent his money lavishly, building several huge families, buying huge houses, and huge carriages. He was sort of a spiritual ancestor to Elon Musk: he liked carriages, so he started a carriage company to build himself carriages (which then went on to make hearses, because: big) A bunch of American robber barons trying to exclude someone for being declasse, that’s kind of funny, isn’t it?

hit miss engine

old maytag hit miss engine

Hit/miss engines are wonderful old industrial age things. This is a hit/miss engine for powering an old Maytag washing machine. You can get it on Ebay for a mere $700! [ebay]

Hit miss engines are called that because of the way they work: there is an inertial governor that spins a weight out while the flywheel is at a certain speed (you set the speed using the governor) when the arm of the governor drops, it makes a circuit and the spark plug can fire the cylinder. So, the engine will automatically idle, but as soon as you start taking power off on the flywheel it’ll fire more frequently as necessary to keep the flywheel’s speed up. You start it with a single kick on the large lever to the upper right, which starts the flywheel spinning slowly, then the engine immediately “spins up” and then starts to idle. It’s a great example of a simple feedback control loop. The castings are large because the thermal mass dissipates the heat. Some of them have a ‘radiator’ for water cooling – a big tank on the top that just evaporates and cools the whole block as the motor heats up.  I know a guy in Florida who has an old hit/miss that he hooks up to an alternator when there’s a power failure. It works fine. I never understood why anyone buys those little “portable power” gas engines – they’re so loud and complicated. Maybe it’s because of the “portable” part. My grandfather grew up on a farm where they used a hit/miss engine to pump water; it was state of the art in 1920! There is a fellow on youtube [here] with an absolutely gorgeous hit/miss restore with an alternator; it’s a typical 1930s field/portable power system.

Comments

  1. Reginald Selkirk says

    My understanding of evolution comes from machines, not biology: there is just as much interchange of ideas (genetic material) and experiment (survival) as there is in the wild.

    Possibly more. Some things are possible in the world of ideas which are not possible in the world of genes. Like transfer of features from one brand to another. And the occasional scrapping of an existing idea in favor of something that is basically better, but could never have evolved gradually.

  2. rejiquar says

    OK, this is why I just don’t get mechanical things (though as you say, having them laid out in an evolutionary line makes it a bit easier). After looking at your vid of multi-ends braiding machine (the one that does four flat threads per stitch—which btw can also be done with `flat’ silk by hand, though it’s a pest, and often involves kakudai, towels & spinning the tama to keep or resist the twist) & reading the comment about it working like a sewing machine, I looked at 3 different animations of stitch formation (not to mention having watched my old sears kenmore do this for years…)

    ***

    So far so good, except for both the wardell cam ring & the basic sewing machine stitch, the loops (needle thread/outer bobbin threads) have to go around the bobbins. Which are mounted on pins. So I just can’t wrap my head around why those theads don’t get hung up on the pins/supports that hold the bobbin in place, since in both cases the threads appear to be going behind or under the bobbins.

    ***

    And in case of the sewing machine we’re talking about 100+ year old tech. Sigh.

  3. says

    Rejiquar@#2:
    The polished disc at the base of the bobbin is two things: heavy and slippery. And the disc keeps the bobbin from pulling forward. So the thread slides around the outer edge of the bobbin on the disc; the bobbin is in its cradle because of gravity. I believe that is also a safety mechanism: if the bobbin binds it flies out of the cradle. The failure modes of braiding machines all seem to be “big knot and broken thread”.

    In a sewing machine, the magic is all in the bobbin carrier, which holds the bobbin and flips the thread around it.

    Edit: it is possible that I do not understand this either!

  4. rejiquar says

    Ah, so that’s where that blurry gif in the Threads link came from! And now I know what a walking foot looks like.
    ***
    But you see the needle thread loops around the bobbin (& its case). And, come to think, the bobbin is pinned into the case, but the case just sort of sits in place. So I guess the loop of thread goes around the entire bobbin case? Jeez, no wonder needle threads break and wear out!
    ***
    But that means in your other (wardell) video the fiber is somehow sliding under those big triangular-ish metal things the bobbins are sitting on, correct? Which is fine, but how does it keep from getting caught in the upper ring that presumably holds those inner bobbins in place…?

  5. Raucous Indignation says

    Marcus, I checked out that video of the hit/miss. You are absolutely correct! Why would I want a modern portable generator that is quieter than 50 dB and churns out 3000 watts when I could pick up one of those hit/miss things and rig up my own alternator for more money? It’s preposterous; all this fuel efficient, quiet, portable energy-producing technology is just so unnecessary!!

  6. Raucous Indignation says

    I’m sure with a little tinkering I can make one of those hit/miss contraptions CARB compliant.

  7. machintelligence says

    You missed one of the important feature of a hit and miss engine: it isn’t just the spark for ignition that is interrupted.

    The intake valve on hit-and-miss engines has no actuator; instead, a light spring holds the intake valve closed unless a vacuum in the cylinder draws it open. This vacuum only occurs if the exhaust valve is closed during the piston’s down-stroke. When the hit-and-miss engine is operating above its set speed, the governor holds the exhaust valve open, preventing a vacuum in the cylinder and causing the intake valve to remain closed, thus interrupting the Otto cycle firing mechanism. When the engine is operating at or below its set speed, the governor allows the exhaust valve to close. On the next down-stroke a vacuum in the cylinder will open the intake valve and let the fuel-air mixture enter. This mechanism prevents fuel consumption during the intake stroke of “miss” cycles.

    from Wikipedia
    There are videos on YouTube about converting old lawnmower engines to hit or miss.

  8. Johnny Vector says

    Somewhat off topic, but since we’re considering exposed drive trains…

    My family’s camp in Maine used to have a piston type water pump, belt-driven by a standard AC motor (driven by a 4 kW generator). This was because one member of the family (J) owned a hydraulics company and by god he was going to provide a pump that we didn’t have to pay for. So every year he took it home in September, disassembled it, cleaned it, re-waxed or replaced the leather seals, and brought it back next season, where it chuffed away for 15 minutes at a time pumping up the 40 gallon tank.

    Between the rotating open belt, the 100 dBA of the generator, and the unprotected knife switch for the AC power, it was a place of OSHA nightmares. (Fortunately nobody is employed at the camp, so obviously totally safe.)

    About 15 years ago we finally replaced the pump with a commercial shallow well pump. (It took two years; J reinstalled his pump the first year after the new one went in, and we had to re-uninstall it.) Then I replaced the knife switch with a UL listed cutoff. And a couple years ago I put up a solar panel and took the generator to a scrapyard. Spent the entire six bucks I got for it on ice cream (Gifford’s; totally worth it!). It’s nice not having to worry about dying a horrible death when pumping water.

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