Gears

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Gears

Post by cheese » October 12th, 2017, 8:47 pm

Just been looking around and have had a hard time finding gears. After doing some calculations, I need around a 4:1 - 7:1 gear reduction. Is it ideal to use metal gears or will plastic be fine? I've had a hard time finding any good metal ones.
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Re: Gears

Post by shrewdPanther46 » October 13th, 2017, 5:50 am

I would suggest metal, as they wont shear under large forces. Plastic gears are simply inconsistent and never reliable in comparison to metal gears.

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Re: Gears

Post by holmonsterX » October 13th, 2017, 8:12 am

Me and my school are new to this category, we were wondering how you get your calculations to get the correct gear size for the car and what material or brand is the most effective.

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Re: Gears

Post by cheese » October 13th, 2017, 1:02 pm

holmonsterX wrote:Me and my school are new to this category, we were wondering how you get your calculations to get the correct gear size for the car and what material or brand is the most effective.
There is another subtopic by retired called "build ideas" that explains it a little.
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Re: Gears

Post by cheese » October 13th, 2017, 1:08 pm

Ok, so metal will probably be the best. Does anyone know where to get metal gears then?
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Re: Gears

Post by shrewdPanther46 » October 13th, 2017, 8:13 pm

You can derive an optimal gear ratio with a torque curve for the motor you are planning to use(along with desired rpm to travel a certain distance)

In terms of where one can obtain metal gears: you can't really go wrong buying gears from any source. Just make sure that the gears u buy have the same pressure angle(I think that's what it is called) so they mesh, and they have the required bore diameter.

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Re: Gears

Post by cheese » October 13th, 2017, 9:32 pm

shrewdPanther46 wrote:You can derive an optimal gear ratio with a torque curve for the motor you are planning to use(along with desired rpm to travel a certain distance)

In terms of where one can obtain metal gears: you can't really go wrong buying gears from any source. Just make sure that the gears u buy have the same pressure angle(I think that's what it is called) so they mesh, and they have the required bore diameter.
Ok, thats what i thought. (its pitch angle btw)
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Re: Gears

Post by retired1 » October 18th, 2017, 2:27 pm

Actually, you need both gears to have the same pitch angle and the same pressure (14.5 or 20) angle to avoid problems.

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Re: Gears

Post by shrewdPanther46 » October 18th, 2017, 2:36 pm

I did some research, and found that the factor that must match for two gears to mesh is modulus, which is the same thing as the pitch diameter (I think factors that influence DP, or P is the two things mentioned above). Can someone please clarify for me?

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Re: Gears

Post by Unome » October 18th, 2017, 3:00 pm

shrewdPanther46 wrote:I did some research, and found that the factor that must match for two gears to mesh is modulus, which is the same thing as the pitch diameter (I think factors that influence DP, or P is the two things mentioned above). Can someone please clarify for me?
A gear's modulus is a measure of tooth size - typically a ratio between the diameter and the number of teeth. Two gears with the same modulus will mesh properly. It's not the same thing as pitch diameter, but it is usually computed using the pitch diameter (as opposed to major or minor diameter).
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