CNC Upgrade to Guitar Pickup Winding Machine

The idea of winding inductive guitar pickups by hand is almost unthinkable. It uses extremely thin wire and is a repetitive, laborious process that nevertheless requires a certain amount of precision. It’s a prime candidate for automation, and while [Davide Gironi] did exactly that, he wasn’t entirely satisfied with his earlier version. He now has a new CNC version that is more full-featured and uses an ATMega8 microcontroller.

[Davide Gironi]’s previous version took care of winding and counting the number of turns, but it was still an assisted manual system that relied on a human operator. The new upgrade includes a number of features necessary to more fully automate the process, such as a wire tensioner, a wire guide and traverse mechanism (made from parts salvaged from a broken scanner), and an automatic stop for when the correct number of turns has been reached.

guitar_pickup_winding_sample_microscope

All kinds of small but significant details are covered in the build, such as using plastic and felt for anything that handles the wire — the extremely fine wire is insulated with a very thin coating and care must be taken to not scratch it off. Also, there is the need to compute how far the traverse mechanism must move the wire guide in order to place the new wire next to the previously-laid turn (taking into account the winding speed, which may be changing), and doing this smoothly so that the system does not need to speed up and slow down for every layer of winding.

This system is still programmed by hand using buttons and an LCD, but [Davide Gironi] says that the next version will use the UART in order to allow communication with (and configuration by) computer – opening the door to easy handling of multiple winding patterns. You can see video of the current version in action, below.

Winding guitar pickups is something that has spawned numerous partially automated solutions, like this winding workstation based on an old sewing machine. It’s very interesting to see what people come up with in order to take things to the next level.

34 thoughts on “CNC Upgrade to Guitar Pickup Winding Machine

  1. Doesn’t really require precision. buddy of mine makes custom ones and just uses a drill and randomly fills the wire on it. and yes he gets premium $$$ for his 100% custom guitars and pickups. a lot of guys like the unique sound of his guitars… something that I absolutely can not tell the difference in from a standard cheapie strat. But then some guys claim the wood on an electric guitar makes a difference…. and mathematically that is impossible.

    1. if the angle made by the spooling hole and the width of the coil is small enough it will wind itself quite neatly.
      if you made a real hash job of it the final winding might have a larger diameter. i’m sure there is plenty of opinion on how this would alter the sound.

    2. I’ve heard the claim that hand wound pickups sound better than neatly cnc wound pickups. Sound like nonsense but it isn’t impossible that the more random winding causes a difference in the interwinding capacitance and thus in sound

    3. apply C37 to a CD to see what it can do? boggles the mind.
      As for the wood which doesn’t even touch the string i would suggest any variation is more likely due to differences in string length/tightness/tuning rather than the wood. then again f you have to look at an fft on a scope to appreciate the difference…

      1. everyone who says :if you have to look at a FFT to see the difference” is forgetting one thing; a electric guitar is played thru a amp that has gain; minor differences can be amplified greatly.

    4. Timothy…I’ve been playing guitar for 35 years. The wood that the guitar body, the neck and the fingerboard al have small, but perceptible influences on the sound that one hears after coming by out of the amp. The string vibration is transferred to the body via the bridge, fingerboard via the contact with the finger pressing on the board (the fretwire material can add to this too) and at the neck proper via the nut. The influence is via mechanical resonance that feeds back in the vibrating string and has a slight but audible effect on the sound from the attack as the string is plucked all the way though the decay as the energy in the string is spent. Even the neck attachment technique gas an effect. A bolt on neck does sound different than a glued on, set neck. The biggest influences are the puck ups and the type of bridge. The original signal has its gain boosted by several orders of magnitude, so the relatively minor influences, of the materials in question, via the mechanical resonance differences of each can be heard.

    1. https://en.wikipedia.org/wiki/Humbucker
      Weird name; most coils are wound in a way to cancel out mains hum much like the inductor in a power supply does. Usually two windings and multiple sets of pickups.
      My brother had an electric guitar and all of the pickups and the windings were connected to several switches. You could really hear a difference when a coil was reversed.

      I’ve had very little experience with guitars; can’t learn to play. :(

      1. Pickup coils being reversed produce a partial spectrum cancellation therefore modifying radically the sound.
        If you had two identical coils in the same exact place then reversed one of them their output voltages would cancel each other and you got nothing from the amplifier. But since there are no two identical coils in the known universe and more importantly they’re spaced by several centimeters, their sound vary considerably so that if one of them is reversed only a few frequencies are canceled. Some frequencies are also actually summed because of the phase rotation since they pick up the signal under different parts of the same string.
        You can get a great deal of different sounds if you wire all pickups so that you can split, phase reverse and vary the volume of all of them independently. I made some modifications like that in the 80s, guitarists usually loved the sounds, but almost none of them wanted their axe pickguard to look like a Moog front panel:=)
        Lesson learned: guitarists just love simple things; too many knobs and they panic.

        1. Thanks for the detailed explanation!
          That is a very good point; some people do it, but adding several knobs and switches isn’t optimal. I did not consider that. :)

    2. Check out a brand of pickup known as Zexcoil. The innovator is a Dr. Lawing, an MIT-minted, PhD engineer. I think he’s innovated, patented and is currently marketing what you’ve described. He lives in the greater Phoenix, AZ area.

    3. Having 4 winding of the same characteristics is probably fairly limiting in that you have 3 combinations: series, parallel and series-parallel. So this would make a difference but notes do not have the same spans or spacing. For notes – to halve or double is to change octave and not just to step up or down a note or tonality.

      So – I think this would be worth a ‘play’ but I also think having for different windings of different lengths and with four different tuning (capacitor) circuits would be *more* interesting to ‘play’ with.

  2. The debate over what sounds good will rage for centuries to come.

    I used to design audio amplifiers for a small company and spent a fair bit of time researching the market at the time. It appears the more outlandish the claim of what sounds good is directly proportional to the price charged and inversely proportional to the physics behind the claim..

    I suspect that a lot of the thought of what sounds good in audio production can also be applied to what visual artists think looks good.

    A photograph will reproduce an image more accurately than a painting.

    A transistor amplifier will reproduce a sound (typically) more accurately than a valve amplifier. But an audiophile will claim the valve amplifier sounds better than the transistor amp.

    I’m guessing a perfectly wound coil would pick up the vibrations of the string more accurately than a hand wound coil.

    Do people want perfect reproduction or something they find pleasing to the imperfect response of their audio receptors (ears)

    1. Quote: “A photograph will reproduce an image more accurately than a painting.”

      Not necessarily, an artist has precise choice of the palette used. A photograph has a fixed and very limited core spectrum.

      Quote: “A transistor amplifier will reproduce a sound (typically) more accurately than a valve amplifier.”

      Transistors distort more even harmonics and tubes distort more odd harmonics making the sound more “warm” but not at all more accurate.

      In the end perceived “richness” of the sound is more a deciding factor than any “accuracy”.

      ie It’s all just personal preference.

        1. … so you can listen to Jimi Hendrix’s guitar solos in their original, undistorted, clean-tone glory!

          It’s a multi-step path between the production of the sound and you hearing it. Where the definitive reference experience lies along that path is even debateable. Some folks dig the sound of their speakers / preamps, and want that in their signal chain.

          HiFi is weird.

      1. You’re also wrong about cameras. Modern devices can capture a huge amount of the spectrum, well beyond SRGB, and the parts they can’t reproduce well still don’t make the painting more accurate as a complete image. That’s not to say that people can find the painting more pleasing, but always the photograph is more accurate.

        1. @[Sweeney]

          Modern cameras …. and then you display the image on a LCD monitor that has only three (additive) primary colors that themselves have very limited spectrum.

          If you compare sound and or color then you need to compare the whole chain of events right through to human perception especially for color as it doesn’t exist in the real word. Color is *exclusively* a human (or other animals) perception.

          Transistors may be accurate to some some degree and we measure that *degree* on a logarithmic scale (dB) because our sound perception is logarithmic. On a scale of zero to ten you may say that 1 is small on a linear scale but that same 1 is huge on a logarithmic scale. In fact the correct scale to measure human perception is dBmOp. With the ‘p’ meaning psophometric weighted to human perception.

          Color is a whole different kettle of fish and most humans have varying perception, varying spectral center points of the color perceptive cones. There are less humans that have *correct* color perception than there are those who have NO color perception and most people are somewhere between.

          Anyway, I don’t want to get into an argument here. I was just sort of saying – what point is there to incredible accuracy when at the end of the the day different people will have different perceptions – let them have what the personally like and enjoy.

  3. Friend of mine was once invited round to his pal’s place to ‘Audition’ his HiFi system –

    – the $$$+ turntable was mounted on a concrete pillar set deep into the foundations of the house.

    – the demonstrator carefully removed the LP from it’s sleeve, placed it on the turntable, started the turntable, then gently placed the tone arm/stylus on the first groove..

    “Listen!” he says –

    ..

    “Errr-? what? I can’t hear anything??”

    “Yeah! It’s Great, Isn’t it???!”

    (Was a silent ‘surface noise/Wow/Fluttter test reference LP)

  4. The specific sorts of ferrite materials are open however standard sort of ferrites are nickel-zinc ferrite and manganese-zinc ferrite. Manganese Zinc is having maximal flux thickness and its sensible repeat Bobbins range is under 5MHz however expelled standard mode inductors that impedance is staggering decision up to 70MHz.

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