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Thread: Good for lumia??

  1. #1
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    Default Good for lumia??

    Granted, this would most likely be prohibitively expensive for a simple lumia rig but to be able to get this rotate as slow as you wanted... Since you could also change the speed, you could fit it with different discs/effects. The size would be a plus, too. No bulky gear reductions. Just a thought. Don't let the title of the video fool you. He also mentions 1 RPD along with 120K RPM.

    This could also be good for selecting effects from a poly20 wheel while also having the ability to change out the poly20 for a lumia disc.

    Last edited by absolom7691; 08-18-2020 at 14:00.
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    that's a great idea. what does it take to drive them?

    Quote Originally Posted by absolom7691 View Post
    Granted, this would most likely be prohibitively expensive for a simple lumia rig but to be able to get this rotate as slow as you wanted... Since you could also change the speed, you could fit it with different discs/effects. The size would be a plus, too. No bulky gear reductions. Just a thought. Don't let the title of the video fool you. He also mentions 1 RPD along with 120K RPM.

    This could also be good for selecting effects from a poly20 wheel while also having the ability to change out the poly20 for a lumia disc.

    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    Not sure. Probably a question for Ryan or Bill.
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    Quote Originally Posted by swamidog View Post
    that's a great idea. what does it take to drive them?
    Machdsp so i reckon similar to any regular galvo but single unit.

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    Two coils plus a permanent magnet core is a PM Core Resolver Motor. Three coils makes a Synchro with a PM core. In this case, the stator coils are wound ninety degrees out of phase with each other. On a Synchro the coils would be 120' out of phase with each other. Also known as a Quadrature Driven Torquer for the two coil version.

    This concept is not new by a long ways. However Team Scannermax has probably built one that is three times faster then the next nearest device I can think of. I would not be surprised if that unit produces say four world records.

    The actual concept goes back to well before WWII. Great for aiming ship's guns, or indicating a direction on a aircraft instrument.

    The drive waveform to the two coils is the sine and cosine of the desired shaft angle. The resolution is incredible and there is no stepping or cogging unlike a stepper motor. Hook it to one quadrature oscillator of an abstract console and the shaft angle would follow the oscillator as it draws through a circle. You get, if I remember right, a shaft position that is the Arc Tangent between the two input angle vector magnatudes.

    The drive device for computer control is known as a Digital to Resolver Converter. Basically a DAC Pair with Bipolar output. Ie Two 12 bit Dac outputs gets you 4096 discrete angles.
    If you know what your doing you could get about 250 degrees of control with a dual potentiometer with no processor needed. If it is something like just driving a Polysector 20 Grating, I could drive the device with an array of resistors and pushbuttons to go to any sector on the disk and stay there. . A microcontroller can easily store a 90 degree sector table in ROM, with some bit flipping to get the whole circle, and drive a resolver, or if your clever you could use Cordic.

    Many of you have had a slow set of this concept in front of you in the form of Air Core Meters for car dashboard instruments. Air core car readouts are typically limited by design to 270 or 305 degrees and have a stop to prevent full rotation. LM1819 was my favorite cheap air core driver chip to do this in high school. But air core readouts are Sloooow...

    Where was this used in the past: Aerospace, Marine, Automotive. But almost no civilian use. If you've ever had a CT scan, most machines use a giant resolver wound around the patient space with an excitation coil on the rotor to help determine where the rotor is. Because nothing else has the resolution and repeatability of a resolver sensor with interpolation.

    I could go into a lot more detail, but I don't want to spoil Bill's fun.

    Beautiful design but would use both coil drivers on the Mach DSP.. So one Mach per Motor.

    Yeah, one heck of a Lumia Disk driver.

    Bill has been talking about doing this for a long time, and I bet the world makes a path to his door.

    Kudos..

    Steve
    Last edited by mixedgas; 08-18-2020 at 20:36.
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    Bill demonstrated this motor at SELEM a couple years ago. I wish I had a recording of that presentation because it was really astounding when he was listing off the performance specs.

    One that I remember quite clearly was the torque spec: "40,000 dyne-cm per volt" Holy shitballs, Batman!

    So yeah, lots of potential uses for this thing. Unfortunately, it's going to be expensive. (It's basically a Saturn scanner with a special set of coils and a custom Mach-DSP amp. You can do the math...)

    Adam
    Last edited by buffo; 08-19-2020 at 05:16.

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    Want

    A lot.

    Yo Bill, how can a humble lumia artist get a sample to mess with?

    Thanks...Mike
    Runs with Lasers

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    We have exactly one prototype of the thing

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    The main "Cost Driver" would be the Mach DSP servo driver, and as Steve said, it uses both sides of the driver for operation (What we would call the X and Y axis for typical scanners)

    As of now it is a "product in search of an application" as Bill puts it. But yes, could be very cool for Lumia type effects.

    It definitely wouldn't be a $49 or a $99 or even a $299 product as again the cost driver is the Mach DSP. But for those who need the best of the best, it can't be beaten. Certainly in large volume, using a servo produced by the customer, in lots of several dozen, it could be made much more feasible. But as of now we have 1, with parts to build perhaps 4 or 5 more.

    I'n sure Bill can chime in with more info. It would be interesting to see what David Kumpula could do with it in one of his builds...

    EDIT: All the compliments for the motor and the video but no compliments for the cameraman... I see how it is around here....
    Sincerely,
    Ryan Smith
    ScannerMAX Mechanical Engineer
    ryan {at} scannermax.com

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    Quote Originally Posted by rns0504 View Post
    It definitely wouldn't be a $49 or a $99 or even a $299 product as again the cost driver is the Mach DSP. But for those who need the best of the best, it can't be beaten.
    Yeah, that was my opening statement, that it wouldn't be cheap! lol. Still, as you say, best of the best. What I think is cool is, along with using it as a low rpm motor, it could be used as a servo, specifying a specific degree location for a poly4/10/20 wheel, too.

    It would be interesting to see what David Kumpula could do with it in one of his builds...
    His builds impress and depress me. Impress because come on, his builds are amazing. Depress because it reminds me of the plateaus that are out there! Polishedball makes great lumia builds, too. Chris, as well

    All the compliments for the motor and the video but no compliments for the cameraman... I see how it is around here....
    Damn if I couldn't find a video clip of Chris Elliot in Groundhog Day... "Most people think I hold the camera and point it at stuff. There is a heck of a lot more to it than just that!"
    Those who fail to grasp art are the ones who criticize it.

  10. #10
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    There is a low speed alternative. Probably 50-90$ for the core and 100$ for the driver in 10-20 piece lots but not a Resolver. 10 or 12 bit resolution.
    Note that is not the minimum cost for the driver but allowing for labor of love profit.
    ~
    I know what I would do with one and it DOES NOT involve Lumia. Would be amazing in a club. Oh, I got to file a provisional on this.
    ~
    Hey Ryan, what is the shaft size?
    ~
    As Pangolin videos go, not too shabby... Actually pretty good. Not an easy device to film. AAA++++ Seller, would buy again, fast shipping and excellent communication. ...

    Steve
    Last edited by mixedgas; 08-19-2020 at 10:46.
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