I’ve never calculated the rpm of a drive train before. Does anyone know how I can calculate the rpm on my drive train. Thanks!
I linked a photo of my drive train
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Sure. The wheel RPM is
Motor RPM * Motor gear teeth / Wheel gear teeth.
You should probably double check that all your motors spin at the same RPM when you drive.
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What’s up with your motor placement? I don’t get it
Anyways, calculating rpm is just ratios/fractions.
If a 36 tooth gear is connected to the motor (input) and an 84 tooth gear is connected to the wheel (output), there is a speed decrease because the 36 tooth gear will rotate 84 times every time the 84 tooth gear will rotate 36 times. I believe the normal way to write this is 84:36 although some VEX competitors refer to this as 36:84. If the motor is running at 600 RPM, the RPM of the wheel will be 600 * (36 / 84) or around 257 RPM.
With compound gearing (multiple gears spinning together/stacked/on the same axle/attached to each other with screws or zipties) it’s kinda like that axle or whatever the gears are spinning on is both input and output. Just multiply twice, each time with the appropriate ratio.
If a 36 tooth gear is meshing with an 84 tooth gear which is connected to a 60 tooth gear which is meshing with a 48 tooth gear with the 36 tooth gear spinning at 200 RPM, the 60 tooth gear is spinning at 200 * (36 / 84) * (60 / 48) or around 107 RPM.
Yea I kind realize its bad. Do you have any suggestion on how I can improve my drive train
I’m confused—as far as I can tell, the three motors are powering the three gears in the back. Problem is, those gears have 84, 36, and 84 teeth (or at least they look like that to me). Fixing the motor speeds in code is the only way for this drivetrain to work. Even then, the drivetrain is suboptimal.
Suggestion:
Move the 2 frontmost motors up to the gears second from the front. Add a small gears in the back directly above the already existing small gears (although this might interfere with your vertical C-channels). Move the 2 rearmost motors up to the newly added small gears. For reference:
Although you could just build a drivetrain with another gear ratio. Most of the gear ratios in the Catalogue of Drive Gearings are okay. If you only have 4" wheels, 36 tooth gears, and 84 tooth gears, the drivetrain pictured above is basically your only option (although you could just use four motors instead of six).
Literally me:
Also, sry for the long posts, I kinda suck at writing. (Why are my posts annoyingly long sometimes but my writing for school annoyingly short always?)
Note that I am assuming that you are using motors with the blue cartridge, which gears the motor to a base speed of 600rpm.
You are running your drivetrain at two different speeds. The two motors that are driving the 84-tooth gears are spinning the wheels at 600rpm, while the one driving the 36-tooth gear is geared down to 257rpm (600*(36/84)). This is going to burn your motors out, because you are running them at different speeds. To fix this, you need to move all of your motors to be driving a single gear size.
- If the motors all drive the 84-tooth gear, then your drivetrain speed will be 600rpm, since they are directly powering the wheel without a gear ratio.
- If the motors all drive the 36-tooth gear, then your drivetrain speed will be 257rpm, because 600*(36/84)=257.142857.
I would also like to add that there is a spreadsheet that I’ve found with most gear ratios. Spreadsheet
This webssite is great to calculate.
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