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twinturbostang

What servo for camera pan?

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I'm working on a new FPV machine based on the TwinStar II platform, and am building another camera pan/tilt. I'm wondering what you guys recommend for the camera pan servo. On my E-Starter I was using a Hitec HS55, but I'm not sure it's really up to the task. Was thinking of maybe using a metal gear HS81 instead. That would be much more durable, and have the power to hold the camera and tilt system on top of it.

Any other suggestions? I also may look into doing the servo mod to get 180* rotation, and I didn't know if this was possible with the HS81. I have a servomax module from Kilrah (it's a servo pulse doubler), and that works well. But in the interest of saving weight and complexity, I may consider the servo mod. Can this be done on an HS81?

Edited by twinturbostang

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Servocity sells several Hitec servos with the option of modding them to 180° for you. I think the smallest servo they offer this service for is the HS-85, which weighs 22 grams.

I've used the HS-55 in the past, but the mass of my camera/mount/tilt servo made the ouput shaft sloppy pretty quickly. I've recently switched to a HS-81, hoping for better results.

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I didn´t know for sure how will work in the long term my hs56, but if you have used hs55 then I think karbonite gears should last longer, moreover I only have pan movement

What should be used for tilt? I know must be stronger, but don´t know how much stronger :rolleyes:

Andres

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What should be used for tilt? I know must be stronger, but don´t know how much stronger  :rolleyes:

My feeling is the pan servo should be stronger, because it's at the bottom of the pile, holding everything else up. You also do more panning than tilting, so it needs to be smooth and of higher quality.

What I was thinking was using a metal gear HS81 for the pan, and then a standard HS55 for the tilt. I have no experience with the HS81's though, so that's why I'm asking if it's a good servo.

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It depends on the mount. If you use one like mine (the camera being held on top of a laid tilt servo) the tilt one will have more load because of the camera's mass being further from the axis of rotation. The bottom servo has nearly no effort around its axis, it will just hold the weight vertically which asks nothing from it.

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I see your point. However, with the camera directly on top of the "stack", when you tilt forward or backward, you will be introducing a side loading on the pan servo's shaft because the weight is now not directly over the shaft.

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Indeed not, but what I mean is that won't induce a torque needing the servo's motor to compensate it. It will however be the case on the tilt servo.

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It's the cased KX131 (KPC-S226). I don't know... 1 ounce maybe? Seems like the HS55 should be able to handle the weight. It has 15 oz-in of torque. So as long as you don't mount the camera too far from the rotation point of the servo, I'm thinking it should be ok. But if there is a better option out there, please let me know.

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I'll try to relate my experiences with the HS-55 again. It's plenty stong enough for this application since no real forces are acting against rotation.

However, this servo uses the case as a bearing to support the output shaft. I've found that in my application the weight of the cased camera+tilt servo+mount acting on the servo output shaft makes it sloppy real quick. This is compounded by the fact that the components are mounted far above the top of the case, increaseng the lever arm action, and the only gets worse with a mild 2-3g load.

I'm currently evaluating an HS-81 in this application. It's still uses the case as a bearing surface, but it's beefier than the HS-55 and should take more of this abuse.

If it doesn't hold up, I'm going to use an HS-85 servo with uses a real bearing supported output shaft. I really hate to step up to a servo that weighs 22g, but a side benefit is this servo is offered in 180° rotation from Servocity so I can remove the Servomax module.

As you noted, if you can keep the mass of the camera/tilt servo/mount down, you'll be less affected by this. Looking at my current version, it's pretty hefty.

Perhaps instead of beefing things up, I should get an uncased camera and use Kilrah's design. My FPV platform is proven now and I'm not worried about crashing. That's the main reason I chose the cased camera.

lg-69722.jpg

Edited by rob10000

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