# Best speed reducer for a simple project (gearbox design choice)

• awer
In summary: If the dimensions are too tight for a parallel input and output, a train of gears will need to be used.
awer
TL;DR Summary
I'm building a pan/tilt mechanism with a small stepper motor, and I need to design a simple 3d printable gearbox with a 20:1 ratio (aprox)
Hi,

As the summary says, I'm trying to design a simple gearbox with an approximate ratio of 20:1. I have two preliminary designs, one using a worm gear and another using a train of 5 spur gears. Both designs give me the desired ratio, but I really don't know which one I should choose.

The application requires an output torque of around 5kg/cm, and a maximum speed of 0.5RPM.

Both designs are pretty much the same in terms of manufacturing cost.

Coud you please suggest which option is better and explain why?

Thanks

Some things to consider when making this decision:

1) Do a tolerance stackup calculation to make sure that it can be assembled and will work with realistic worst case part dimensions.

2) After #1 above, calculate the total backlash with realistic worst case part dimensions. Compare to the maximum acceptable backlash. You did calculate allowable backlash, didn't you?

3) Does the manufacturing cost include assembly labor?

awer said:
Summary: I'm building a pan/tilt mechanism with a small stepper motor, and I need to design a simple 3d printable gearbox with a 20:1 ratio (aprox)

Hi,

As the summary says, I'm trying to design a simple gearbox with an approximate ratio of 20:1. I have two preliminary designs, one using a worm gear and another using a train of 5 spur gears. Both designs give me the desired ratio, but I really don't know which one I should choose.

The application requires an output torque of around 5kg/cm, and a maximum speed of 0.5RPM.

Both designs are pretty much the same in terms of manufacturing cost.

Coud you please suggest which option is better and explain why?

Thanks
Generally, worm gear is fine for 20:1 ratios. Train of 5 spur gears would have larger loss and will be less reliable.

P.S. If you have a budget for 5 gears, may be better to consider a comparison between worm gear and epicyclic gear. Most of stepper motor reduction gears are epicyclic.

sysprog
The packaging constraints also enter into the picture. A worm is typically at right angles to the axis of the gear, whereas either a compound gear train on fixes axes or a compound epicyclic train have parallel input and output axes.

## 1. What is a speed reducer and why is it important for a gearbox design?

A speed reducer, also known as a gear reducer, is a mechanical device that reduces the rotational speed of a motor or engine while increasing its torque. This is important for a gearbox design because it allows for the efficient transfer of power from the motor to the desired output.

## 2. What factors should be considered when choosing the best speed reducer for a simple project?

There are several factors that should be considered when choosing the best speed reducer for a simple project. These include the desired output speed and torque, the size and weight of the reducer, the efficiency and durability of the reducer, and the cost and availability of the reducer.

## 3. What are the different types of speed reducers available for gearbox designs?

There are several types of speed reducers available for gearbox designs, including worm gear reducers, spur gear reducers, helical gear reducers, and planetary gear reducers. Each type has its own advantages and disadvantages, so it is important to carefully consider the specific needs of the project before choosing a type.

## 4. How do I determine the appropriate gear ratio for my speed reducer?

The appropriate gear ratio for a speed reducer can be determined by dividing the output speed by the input speed. This will give you the gear ratio, which can then be used to select the appropriate gear reducer. It is important to choose a gear ratio that will provide the desired output speed and torque for your project.

## 5. Can I use a speed reducer for a gearbox design in any type of project?

Speed reducers can be used in a variety of projects, but it is important to carefully consider the specific needs and requirements of your project before choosing a speed reducer. Factors such as size, weight, and efficiency may vary depending on the project, so it is important to choose a speed reducer that is suitable for your specific application.

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