ServoBender, The Electronic Pedal Steel

Servo

You’ve most certainly heard a pedal steel guitar before, most likely in any ‘old’ country song, or more specifically, any country song that doesn’t include the word ‘truck’ in its lyrics. Pedal steels are strange devices, looking somewhat like a 10-string guitar with levers that change the pitch of individual strings. Historically, there have been some attempts to put a detuning mechanism for individual strings in normal electric guitars, but these are somewhat rare and weird. [Gr4yhound] just nailed it. He’s come up with the perfect device to emulate a pedal steel in a real guitar, and it sounds really, really good.

The imgur album for this project goes over the construction of the ServoBender in a bit more detail than the video. Basically, four servos are mounted to a metal plate below the bridge. Each servo has a spring and cam system constructed out of 3D printed parts. The detuning is controlled by an Arduino and a few sustain pedals retrofitted with hall effect sensors. Simple, really, but the effect is astonishing.

[Gra4hound]‘s contraption is actually very similar to a B-Bender where a guitarist pushes on the neck to raise the pitch of the B string. This setup, though, is completely electronic, infinitely adjustable, and can be expanded to all six strings. Very, very cool, and it makes us wonder what could be done with one of those freaky robot guitars, a soldering iron, and a bit of code.

Video below, because you should watch it again.

Comments

  1. Travis K says:

    Man that is just cool. Very effective mechanical and electronics engineering , so simple. and a great end result.

  2. Rusty Shackleford says:

    Holy cow! A HAD post about a musical instrument with ACTUAL music! Props!

  3. LCL says:

    I’m filing this under ‘shut up and take my money!’ Not only does it sound great, but it has a nice finished look to it.

    On a related note, does anyone know what songs he’s playing?

  4. Ryan Voots says:

    Could a string breaking cause the servo to get damaged from the counterweight? It certainly looks like a really cool way to do it and it sounds awesome.

  5. F says:

    great idea but overengineered

    two strings is sufficient

    http://www.inthequeue.com/cbnet/articles/9703BassPlayer.htm

    millions of peaches can’t be wrong

  6. RandyKC says:

    What do you get when you put some musical chops together with some engineering abilities?
    Answer: Guitar Coolness!!

    • RandyKC says:

      Why not have the servos pull down instead of on a cam. You’d have greater force and smoother control and a better response time.

      Love the music, you should start a YouTube channel.

      • kaidenshi says:

        I think pulling down would be too much friction on the string where it meets the bridge, eventually breaking the string. Using the cam, he’s essentially stretching the string laterally without using the bridge as a rigid pulley. Plus, this is basically bolt-on, whereas having the bender pull downward would mean cutting a hole in the body for it to fit.

        It takes a good guitarist with the mind of an engineer (or a good engineer with a musical bent) to even come up with something like this, so I’m sure he knows what he’s doing. It certainly sounds great, I’m an average guitarist at best, but I didn’t pick up any issues with response time or control.

        • RandyKC says:

          As a good musician you know all instruments have their quirks and part of playing is working with the quirks.
          It’s just in the current design he feeds the wire through four drilled ot screws (difficult to machine which is why he prob went with brass) and the string is stretched over two edges. Lots of broken strings that way. If you went with a rod for the bridge and fixed the other end normally, then generated the force down on each string seperately between those two points, you could cut down on the sharp edges.

  7. piotrsko says:

    And it uses an arduino!

  8. strider_mt2k says:

    There is nothing not cool here.
    Some nice chops too!

  9. Rock K. says:

    So when can I buy one?

  10. echodelta says:

    It’s more than I expected, variable bend no less. This could work on the next version of the sustaining steel I am making. Since it only takes one hand to bar the other is free to bend hand levers not needing foot pedals. I am already running everything on a laptop battery, I don’t need the additional power drain.
    The counter tension not “weight” concept would be best if in line, not at right angles. I would like to hear if it remains stable in tuning after wear. Tuning by good trimpots is appealing. The photos still don’t show the details of the counter tension springs well enough. The differential tuning concept still has merit, it might hand levers easier to manipulate.

  11. Mushroomglue says:

    Nice idea, nicely done, and nicely played. The only thing I’d be worried about is stress on the servos. Just a thought as an alternative way to do it; Rather than stretching the string, if you altered the bridge so you could move the bridge peices back and fourth by about an inch (smoothly, so you’d have to do something about the ends of the hight adjustment screws) and fix the strings on a fixed point on the body, you could then use the servos to move the bridge pieces, effectively shortening the string (Similar to using a guitar slide) rather than stretching the string. This’d probably be a bit trickier to engineer (as it’d need a fair amount of re-engineering of the bridge) but woulden’t need the counterweight springing, and would reduce servo wear.
    Still, really nicely done

    • kaidenshi says:

      The problem with movable bridges (and I’ve had many guitars with them in a traditional manual style) is that it would be much more difficult to do “on the fly”, servos or not. And wear would still be an issue; the closer you move the bridge towards the tailpiece, the more force is necessary to push the bridge under the tension of the strings. On the neck side, the string tension is spread out over the majority of the length of the string, but between the bridge and the tailpiece, there is a lot less string to work with, making it very difficult to force the bridge closer. This puts a lot of friction on the taut tail end of the string, making it much more likely to break.

      • Mushroomglue says:

        True. I hadn’t thought of that. In that case, I suppose that you could always put an individual servo-operated slide on each string around the bridge area or something like that. It’d probably need some sort of cover to stop you keeping catching it, though.

  12. Irish says:

    Very sweet build! +1 for sure. I would only recommend two simple changes/additions. GraphTech saddles on the bending strings to help minimize friction, and an awesome chrome plated cover to go over the servo plate which would be reminiscent of the old Telecaster “ashtray” bridge covers. With the servo plate covered, people would be listening to this guitar wondering how does he get that awesome sound!

    Okay. Enough! Take my money already!

  13. echodelta says:

    More questions. How long to change a string? Wound string at sliding point will fail at winding first and buzz. Still can’t figure out springs at servos. They are not part of counter tension.
    Steel guitars use a roller action at the end of a lever, so standard strings slip in to the lever. Most importantly there is no sliding action across the bend.

  14. Joe Bonasses says:

    Mechanical tremolo! Just a bit of code and you’re there!

  15. What a cool sound. I also wonder about changing a string and what it might involve.

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