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Thread: Balance my camera

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    Default Balance my camera

    Just going through my plans to build a camera slider.
    To keep weight, bulk and price down, I want to use the smallest stepper motors that still adequately do the job.
    I'm considering using counter weights for the slider part of it. I suppose I could just muck with weights after I've built it but I'm curious about the maths.

    I found this site and dunno if it's the right formula or not but I don't really understand it anyway.


    Also, I don't want friction to be a part of this calc, and just for kicks let's say the camera weighs 1kg. Oh and I know you're gonna say "but adding a counter weight IS adding weights" but we'll ignore that for now. I have other design ideas too, and I'm only mostly concerned with the camera's weight at different slider angles.

    So, consider the slider is level. I don't need any counter weight the keep the camera balanced with the motor.


    If the slider is at 90deg, the counter weight should be the same as the camera.


    Ok so what if the slider is at 45deg. Is it as simple as the counter weight being half that of the camera ? I doubt it.


    Then what if the slider is at say 30deg or 60deg ?

    Last edited by loopyloo; 14-10-18 at 11:36 AM.



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    SIN(x)

    SIN(90)=1
    SIN(60)=0.87
    SIN(45)=0.71
    SIN(30)=0.5
    SIN(0)=0
    Yes I am an agent of Satan, but my duties are largely ceremonial.

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    Rather than using all sorts of weights, would it be simpler to use something like a 'Screw Jack' (miniture sized) to drive the camera to and fro along its track?
    To operate Railway 'mechanical' signals connected by wire to a lever up to 500 metres away, they used a pulley system on the lever end with the wire going through 3 or more pulleys and hanging 'weights' on a signal return arm at the post as well as in one ''Run', a weight was attached to the signal wire.
    While this worked most times, during periods of high and low Temperatures, the wire either tensioned or became slack and a turnbuckle was used to fine tune the 'Run'.
    You havent said how far you want the camera to travel because that too will be needed to be included as well.
    Last edited by gordon_s1942; 14-10-18 at 01:21 PM.
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    Quote Originally Posted by trash View Post
    SIN(x)

    SIN(90)=1
    SIN(60)=0.87
    SIN(45)=0.71
    SIN(30)=0.5
    SIN(0)=0
    Is that sin values or weight ?
    SIN(90)=1kg
    SIN(60)=870grams
    SIN(45)=710grams
    SIN(30)=500grams
    SIN(0)=super light.

    PS Yes, they are sin values. tricky
    Last edited by loopyloo; 14-10-18 at 04:36 PM.

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    Quote Originally Posted by gordon_s1942 View Post
    Rather than using all sorts of weights, would it be simpler to use something like a 'Screw Jack' (miniture sized) to drive the camera to and fro along its track?
    To operate Railway 'mechanical' signals connected by wire to a lever up to 500 metres away, they used a pulley system on the lever end with the wire going through 3 or more pulleys and hanging 'weights' on a signal return arm at the post as well as in one ''Run', a weight was attached to the signal wire.
    While this worked most times, during periods of high and low Temperatures, the wire either tensioned or became slack and a turnbuckle was used to fine tune the 'Run'.
    You havent said how far you want the camera to travel because that too will be needed to be included as well.
    As mentioned in the first post, it will be powered by stepper motors. Also it will be belt driven.
    Distance : It will be a 1.5 metre slider. The distance will have no bearing on counter weight operation.

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    I read your plan and thats why I suggested the 'screw drive' because of the use of a stepper motor.
    I used this method to move Points on a Model Railway because of its very positive movement and there is no slip or backlash encountered.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Silly question, but what are you hoping to achieve? Surely there are already things that can perform this function without having to re-invent the wheel.
    I'm out of my mind, but feel free to leave a message...

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    My thought would be to effectively attach a cable to each side of the Slider say top and bottom, Cable runs all the way around the slider and the drive motor is say at the end. The counterweight is underneath tracking at the same angle on runners and the cable has a few turns around the pulley. The motor is effectively pulling and pushing the cable at the same time and therefor the load is Constant. The cable rather than as shown on the diagrams would be in a loop rather than 2 ends with the drive moving the cable and slider from one side to the other And the counterweight would be level with the camera in the centred position. When the camera went down, the counterweight would go up therefore keeping the load constant at any angle.

    The counterweight would need it's own track/ rails on the other side to the camera unless the camera could run outside and the weight inside so they could pass each other.

    I think the screw idea has a lot of merit and may well be the simplest soloution. If you used Nylon screws and thread block it should be self lubricating removing any dust and grit pickup, VERY quiet as you are probably wanting to shoot vid and of course very smooth. It would also be light, compact and not add any weight the system as a counter weight would.

    Pretty sure there are already Canilever type systems manufactured out there that would allow this so if you are wanting DIY, do what I do, look at the commercial systems, Copy the theory of operation, improve and adapt to your particular needs and get a better product for a fraction of the price.

    Couldn't even begin to think how much camera stuff I have made/ had made like this over the years. Studio track rail system, stable stands, background stands, battery packs, Softboxes, Posing tables, bulk ink supply tanks, Mounts, brackets.... Even made a wi Fi sender so I could beam images back to my event trailer server from 200M away back when such tech from the camera cos cost a grand and had about a 20 M range. Cost me under $100 and it was all just taking cheap, ready made products and their OWM softeater and hooking them together. Don't know how many people told me I was dreaming and it couldn't be done even months after I had been using it without it missing a beat.

    Get hold of a Manfrotto catalogue. They are great! Give you all the dimensions of every product like a blue print so you can build them yourself or have a machine shop turn you up parts if you don't have a lathe or the gear your self for a fraction of the price of buying the often not so quality products.

    The only thing you need to turn it from a DIY home made to a professional Photo product is a can of flat black spray paint.

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    Quote Originally Posted by gordon_s1942 View Post
    I read your plan and thats why I suggested the 'screw drive' because of the use of a stepper motor.
    I used this method to move Points on a Model Railway because of its very positive movement and there is no slip or backlash encountered.
    Nah I'm going for belt as it is heaps cheaper and will allow faster movement If I require it.

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    Quote Originally Posted by lsemmens View Post
    Silly question, but what are you hoping to achieve? Surely there are already things that can perform this function without having to re-invent the wheel.
    Sorry mate, I don't understand your question.

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    Your design appears rather simple; are there any other factors involved? Like a 3 axis gyro stabilised gimbal for the camera to keep the image stable?
    Cheers, Tiny
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    Quote Originally Posted by loopyloo View Post
    Is that sin values or weight ?
    SIN(90)=1kg
    SIN(60)=870grams
    SIN(45)=710grams
    SIN(30)=500grams
    SIN(0)=super light.

    PS Yes, they are sin values. tricky
    Same thing.
    You just factor the weight as you have done.
    The inverse applies to the pressure the weight exerts on the surface.
    COS(x). You could then use that to factor a coefficient of friction if you wanted to.
    I suspect you might consider using it to determine how much force is exerted on that surface.
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