# Rotator for heavy object around 400kg

• Trainee Engineering
In summary: RPM worm gears at 1/6th of the rated speed.In summary, the best rotator for this type of application is a low RPM worm gear.
Trainee Engineering

I want to create rotating platform for my satellite dish equipment which weigh around 400kg. I'm wondering what's the best rotator for this? any OTC device, or DIY?

this is the gear box used for that thread

but pretty sure it won't be able to handle 400kg.
this will be used to rotate on regular interval (once every 15-20 mins), and rotate about 3-5 degrees per rotation. if possible, the rotation is accurate to 0.1 degree, and it also needs to have a "locking" mechanism, meaning, once the rotation is complete, it should be immovable (affected by wind blowing, etc). This will be placed on 4th floor, where wind can be quite strong, especially during rainy seasons.
what's the best recommendation when considering the following factors (sorted on priority):
1. least energy consumption since this is used regularly
2. durability (wear and tear)
3. price

low RPM is fine, as low as 1/6 RPM is fine.

thanks

Last edited:
You have many things to specify & calculate.
Required torque to turn your 400kg object is Torque = (mass moment of inertia of load) x (angular acceleration).
(angular acceleration) is approximated by (delta angular velocity / delta time to accerlate to that speed).
This has been discussed many times and is fundamental dynamics. Once you have the torque, then you can start looking for motors, bearings, mechanical transmission components that will be designed & specified to give you the motion performance you require.

tygerdawg said:
You have many things to specify & calculate.
Required torque to turn your 400kg object is Torque = (mass moment of inertia of load) x (angular acceleration).
(angular acceleration) is approximated by (delta angular velocity / delta time to accerlate to that speed).
This has been discussed many times and is fundamental dynamics. Once you have the torque, then you can start looking for motors, bearings, mechanical transmission components that will be designed & specified to give you the motion performance you require.

ok, but what about the best mechanism (worm gear, pneumatic, etc) when considering the best overall value of:
1. durability (wear and tear)
2. energy consumption cost
3. price

Trainee Engineering said:
if possible, the rotation is accurate to 0.1 degree,
What diameter of the dish at what wavelength do you have that has such a narrow beam that it needs to be so accurately controlled? How will you control elevation in that case?

Radio astronomy observatories do better than 0.1° with much bigger antennas. You will need some way to measure platform azimuth. The platform will probably move against the lock by more than 0.1° as wind forces change, so you will need dynamic control in the form of two slightly opposed servo motors.

Baluncore said:
What diameter of the dish at what wavelength do you have that has such a narrow beam that it needs to be so accurately controlled? How will you control elevation in that case?

Radio astronomy observatories do better than 0.1° with much bigger antennas. You will need some way to measure platform azimuth. The platform will probably move against the lock by more than 0.1° as wind forces change, so you will need dynamic control in the form of two slightly opposed servo motors.

yes, for now, we're still working on azimuth. will follow the model applied in azimuth for the elevation. 0.1 degree precision is best case scenario. if possible, we need no more than 1 degree error. so, if the azimuth is supposed to be 15 degree, then the azimuth ideally falls in the range of 14 - 16 degree

The construction of a tracking system needs to be optimised for the mode of operation. Will your system be following astronomical objects, geostationary satellites, tracking fast low orbit satellites, or Earth based targets ?

for now, it's Earth based target. so, to align between one dish in building A to dish in building B. maybe will use satellite in the future, but for now, it's a simple dish-to-dish alignment.
elevation setting is for later, when we need to account for difference in altitude from sea level of dish A and dish B

Last edited:
AZ-EL will work for terrestrial, but will be useless for tracking low orbit satellites or RA due to axis velocity passing the zenith.

1. durability (wear and tear).
That will depend on environment. Keep electronics and position sensors out of the sun, rain, bird and insect attack. Use small DC electric motors, avoid hydraulic or pneumatic. Gears on slightly opposed AZ motors should be able to be driven backwards against each other through the driven circumference.

2. energy consumption cost.
Minimum operating costs will be with two small electric motors independently driving the AZ circumference. A reduction gear driven, self locking, screw drive will do best for restricted terrestrial EL. Do not use a ball screw for EL or you will have to keep fighting sag due to mass balance or wind pressure.

3. price.
Start using 600 steps per turn shaft encoders for axis angles. They are cheap at $15 from China. Search; 600P/R Photoelectric Incremental Rotary Encoder. Try to avoid driving a mass through supporting shafts that pass through bearings. Instead, dedicate support pins or shafts to measure direction without drive torque, drive the mass through large radius circle circumference by using peripheral belts or friction drive to save on gearbox costs. Baluncore said: AZ-EL will work for terrestrial, but will be useless for tracking low orbit satellites or RA due to axis velocity passing the zenith. 1. durability (wear and tear). That will depend on environment. Keep electronics and position sensors out of the sun, rain, bird and insect attack. Use small DC electric motors, avoid hydraulic or pneumatic. Gears on slightly opposed AZ motors should be able to be driven backwards against each other through the driven circumference. 2. energy consumption cost. Minimum operating costs will be with two small electric motors independently driving the AZ circumference. A reduction gear driven, self locking, screw drive will do best for restricted terrestrial EL. Do not use a ball screw for EL or you will have to keep fighting sag due to mass balance or wind pressure. 3. price. Start using 600 steps per turn shaft encoders for axis angles. They are cheap at$15 from China. Search; 600P/R Photoelectric Incremental Rotary Encoder. Try to avoid driving a mass through supporting shafts that pass through bearings. Instead, dedicate support pins or shafts to measure direction without drive torque, drive the mass through large radius circle circumference by using peripheral belts or friction drive to save on gearbox costs.

what about worm drive? is it resistant to wear and tear (teeth breaking, worm getting dull, grease, friction, etc)?
for DC motor, any recommendations?

Trainee Engineering said:
what about worm drive? is it resistant to wear and tear (teeth breaking, worm getting dull, grease, friction, etc)?
For AZ, a motor driven threaded rod could run on the periphery of a large wooden disk. Over time the thread will press a pattern into the wood. But it would be higher friction and not have sufficient sensitivity to counter wind forces.

Worm gears are expensive, have small diameter output shafts and tend to be heavy or inefficient. You need a drive system that will not be broken by a wind gust.

Your skills at fabrication and the availability of parts will decide your choice of the solution. All I can do is give you a guide to a geometry that will get it going. You can always improve it later to optimise the design.

Baluncore said:
For AZ, a motor driven threaded rod could run on the periphery of a large wooden disk. Over time the thread will press a pattern into the wood. But it would be higher friction and not have sufficient sensitivity to counter wind forces.

Worm gears are expensive, have small diameter output shafts and tend to be heavy or inefficient. You need a drive system that will not be broken by a wind gust.

Your skills at fabrication and the availability of parts will decide your choice of the solution. All I can do is give you a guide to a geometry that will get it going. You can always improve it later to optimise the design.

ok, will look for more info for specs, etc. will come back once I got more to ask. but feel free to drop any suggestions
thanks.

Baluncore said:
For AZ, a motor driven threaded rod could run on the periphery of a large wooden disk. Over time the thread will press a pattern into the wood. But it would be higher friction and not have sufficient sensitivity to counter wind forces.

Worm gears are expensive, have small diameter output shafts and tend to be heavy or inefficient. You need a drive system that will not be broken by a wind gust.

Your skills at fabrication and the availability of parts will decide your choice of the solution. All I can do is give you a guide to a geometry that will get it going. You can always improve it later to optimise the design.

lets say the moment inertia of the disk plus load is 3600 kgm2, and I only need angular accel of 0.5 degrees/s2. does this mean a 32 Nm torque motor will get the job done? is torque output the only thing I need to look out for when buying the motor?
thanks

## 1. How much weight can a rotator for heavy objects handle?

A rotator designed specifically for heavy objects around 400kg can typically handle weights up to 500kg. However, it is always best to consult the manufacturer's specifications for the specific rotator you are using.

## 2. Is it safe to use a rotator for heavy objects at maximum weight capacity?

It is generally not recommended to use a rotator at its maximum weight capacity. It is always best to leave some margin for safety and to avoid potential damage to the rotator or the object being rotated. It is best to consult the manufacturer's guidelines for the recommended weight limits.

## 3. How does a rotator for heavy objects work?

A rotator for heavy objects works by using a motorized system to rotate the object. The object is placed on a platform or cradle, and the motor moves the platform in a circular motion. Some rotators also have additional features such as adjustable speed and angle of rotation.

## 4. Can a rotator for heavy objects be used for different types of objects?

Yes, a rotator for heavy objects can typically be used for a variety of objects as long as they fall within the weight capacity and size specifications. It is important to ensure that the object is securely placed on the platform and that the center of gravity is properly balanced to avoid accidents or damage.

## 5. Are there any safety precautions to keep in mind when using a rotator for heavy objects?

Yes, there are a few safety precautions to keep in mind when using a rotator for heavy objects. It is important to always follow the manufacturer's instructions and guidelines for proper use. Always ensure that the object is securely placed on the platform and that the center of gravity is properly balanced. It is also important to wear appropriate personal protective equipment and to never exceed the weight capacity of the rotator. Regular maintenance and inspection of the rotator is also recommended to ensure safe operation.

• Mechanical Engineering
Replies
8
Views
2K
• Mechanics
Replies
10
Views
2K
• Engineering and Comp Sci Homework Help
Replies
2
Views
3K
• Sci-Fi Writing and World Building
Replies
21
Views
2K
• Programming and Computer Science
Replies
8
Views
2K
• General Engineering
Replies
2
Views
6K
• Math Proof Training and Practice
Replies
67
Views
11K
• MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
2K
• General Discussion
Replies
2
Views
3K
• General Discussion
Replies
9
Views
4K