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Thread: most suitable motor for a shutter?

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    Default most suitable motor for a shutter?

    I thought using a galvo just to pingpong between two angles may be a bit of an overkill. Are there better motor options out there? My requirement is being able to rotate from one angle to another (0, 45) 120 times per second and a torque with an ability to hold a gram of mirror on it. Again for a tiny LED beam rather than laser so safety is not much of a concern.

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    Really appreciate the help, but Vrad will absolutely suck for this. For 25 USD you can get two pairs of slow galvos while a single Vrad starts at 100 USD. Even more of an overkill for this than a galvo.

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    It sounds like you already have your answer. You asked for "most suitable", not "most cost effective" and received quite good advice.

    If safety is not a concern, then it sounds like you're not after a shutter, but a way to steer an LED's output?

    Perhaps it would be helpful for you to disclose your intended application.

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    I don't think something can be suitable for a task without being cost effective. Like using diamond as an electric conductor or heatsink.

    Pangolin products are good for what they are original intended for for people running the kind of business and at the scale they do, for everyone else they are needlessly overpriced. A single Pangolin scanner costs several times more than the competition for being slightly more accurate, same with everything else. Many need that accuracy, many don't. Don't wish to talk about Pangolin or their products here.

    No, I don't have the answer as I clearly stated in my OP.
    I thought using a galvo just to pingpong between two angles may be a bit of an overkill. Are there better motor options out there?
    If it is not an overkill, then let me know because I've clearly stated I'm not sure.

    I explicitly stated that I Really appreciate the help, but you can't expect people to automatically accept your proposed solution either.
    Last edited by shoujin; 04-18-2018 at 05:01.

  6. #6
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Pangolin will sell you large production quanities of that part at a mind blowing price. They don't limit their market to just laser show parts now.

    Steve
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

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    Quote Originally Posted by shoujin View Post
    Vrad will absolutely suck for this.
    And by suck, you of course mean that it's a robust, tested, solid solution that now falls short of your moving-goalpost requirements, right? Just like so many other threads you've started here recently.

    Here's a little tip: if you already have a favorite answer to your question and still decide to ask others for their advice, you are being a dick when you argue with those people who provided said advice. We have a name for people like that: they're called ASK-holes. You're rapidly becoming one, in many threads here.

    For 25 USD you can get two pairs of slow galvos
    Two *PAIRS* of galvos for $25? So each galvo is $6.25 each, including the amp? I would ask for a source, but on second thought - no, there's no point. Even if they are that cheap (which I doubt), the speed and positional accuracy is going to be shit.

    Consider this: 30Kpps gives you 2500 Hz bandwidth on a small step (under 3 degrees) with 3 dB distortion. A 45 degree rotor movement is going to be an order of magnitude worse. And that's at 30Kpps. That barely meets your spec, and this is still with considerable distortion. (Position settling time is an issue with a galvo, remember, and on a large step it will be far worse than 3dB.)

    The VRAD was designed with this exact task in mind, and it is considered by many to be the new industry standard when it comes to projector shutters. (The venerable GM-20 being the old industry standard.) If you think it's too expensive for your project, you should have listed your budget and asked for the "cheapest possible solution" rather than just "a better option than a galvo".

    As Steve mentioned, there are volume discounts available from Pangolin. Also, there are other, smaller versions of the VRAD available beyond the model 1510. Pangolin can provide further information and pricing to you, but at SELEM a few years ago they demonstrated a budget VRAD motor used for self-driving cars that sells for between $6 and $10 each in large quantities. It was about 1/4 the size of a typical galvo. (Note that response time may be slower and the magnetic spring-return effect is not nearly as strong on those smaller units, however.)

    Quote Originally Posted by hitekvoop View Post
    It sounds like you already have your answer. You asked for "most suitable", not "most cost effective" and received quite good advice.
    Took the words right out of my mouth, Rick! He's been doing this all month, and I've had about enough of it too.

    Perhaps it would be helpful for you to disclose your intended application.
    Several people have asked him for this, and each time it's like pulling teeth. It's like, dude, we're trying to help you, but you won't even tell us the design parameters. At some point you have to wonder why we're still trying. (It's worse when you realize he has multiple projects going.)

    I know I've about reached my end. I just don't give a damned anymore - he can figure it out for himself for all I care. It's not like we're ever going to see the finished product anyway. (He hasn't posted any build pics nor given any real indication of ever sharing the finished product with us, so why bother jumping through his hoops?)

    shoujin, if you're still paying attention: this is the effect you're having on people. When someone with a lifetime of experience in a given field tells you something and you begin arguing with them (often before even acknowledging that they tried to help you), that pisses off everyone here.

    You have unknowingly argued with some of the most experienced members of the forum (including an electrical engineer, a Disney Imagineer, a college professor, and a journyman machinist) about topics you clearly do not fully understand. Stop that! There are lots of talented people here who will willingly solve your problems for you - if you ask nicely and are receptive to their advice. Otherwise you can just figure it out for yourself, because several people have already stopped replying to you.

    Adam

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    Spam incoming

    buffo, you always have been unable to take the simple fact that some people may simply not agree with your proposed solution.

    Why is it in every other community including Reddit, Facebook, BlueRoom, LPF, Physicsforums, StackExchange I'm a nice guy but here I am always an asshole to select members? Really makes you wonder.

    No matter how much each time I've try to get out of my way to mention how I am thankful for your time and willingness to help before saying I don't like your proposed solution, you always don't take no for an answer, label it "arguing" and start a cheap message board flamewar and make walls of text trying to psychoanalyze the person you (think you are) arguing with and use every type of logical fallacy (even in your latest post you managed to do three: appeal to authority, ad hominem, strawman) and just making assumptions by trying to link different topics the person has made which you don't even know are related (hint: they aren't).

    You've went so far as to bully several users in this forum into just literally move to another community just to get away from you or start a new account so they wouldn't have to deal with your grudge or continued bullying. I'm not going to mention any names but let's just say some permanent members here have PMd me before explaining me all this. Thank god PMs are protected otherwise I wouldn't be surprised you would be able to convince an admin to disclose them to you.

    And I'm not going to make the same mistake this time and respond to your post because I'll keep getting even longer posts in response as always. I believe I was clear enough in the very beginning of the first reply to you that I, and I quote, "Really appreciate the help". It seems to have flown over you head again.

    Now, knowing you I'm sure you can't help yourself and will respond to every single sentence with an even longer post than your previous one even if I say I am not going to read it so no point in trying to explain that either.

  9. #9
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    Quote Originally Posted by shoujin View Post
    buffo, you always have been unable to take the simple fact that some people may simply not agree with your proposed solution.
    It's not just my solutions you refuse, dude. It's everyone's. This didn't start with me, and it certainly won't end with me either. To be honest, this is only the second time you've disagreed with my idea. But I've been watching, and so have others.

    Why is it in every other community including Reddit, Facebook, BlueRoom, LPF, Physicsforums, StackExchange I'm a nice guy but here I am always an asshole to select members?
    No idea. Why don't you ask your laser questions there? Sounds like you get better responses there anyway. (Don't let the door hit you in the ass, btw...)

    No matter how much each time I've try to get out of my way to mention how I am thankful for your time and willingness to help before saying I don't like your proposed solution
    Dude - for the last time - it's not about me. Recent example? Count Funkula just gave you a great suggestion for your beam splitter. You didn't even acknowledge him - just replied with "4% isn't good enough".

    Had you bothered to be even remotely civil, I'm sure he (or any of the others in that thread) would have suggested angle tuning, varying thickness, and/or optical coatings (some of which are literally as easy as a peel-and-stick film) that would have solved the problem, all for the cost of a microscope cover slip! Hell those are just the solutions that I thought of, and I'm no expert... But none of that happened because of your attitude. Do you see now?

    you always don't take no for an answer
    Projecting much? People tell you why they think a given solution is inadequate. They EXPLAIN their position. Then you say "That's not good enough". Now how, again, is any of this my problem?

    with and use every type of logical fallacy
    Do not confuse someone being stylistic when posting out of exasperation with a formal debate. This is not your high school forensics class and you are not on the debate team anymore. Furthermore, this isn't a moral or political debate about some philosophical issue.

    People here have dealt with these issues using actual machines and actual products. You're arguing from a text book and maintaining that their experience is wrong. Until you can talk intelligently about the process and not just regurgitate what google says, you aren't arguing anything, you're just being annoying.

    I, and I quote, "Really appreciate the help".
    I am not the person you need to be saying that to. I have not attempted to help you nearly as much as others have. (And I'm even less inclined to do so now.)

    Adam

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    Quote Originally Posted by shoujin View Post
    buffo, you always have been unable to take the simple fact that some people may simply not agree with your proposed solution.
    The man is a lot of things, but I'd absolutely not say that. Adam and I talk all the time about various technical projects and different ways to approach them and he's always been open to give and take of ideas. Moreso than most.

    If you look around the room and think everyone else in it is an asshole, odds are pretty good you're the asshole.

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