Quote:
Originally Posted by Andy A.
An exact ratio isn't very important for most FIRST applications. There are a lot of factors in play that make those pristine speed/torque calculations only a rough suggestion. You won't get either the speed or torque that you expect due to frictional losses, voltage drop during a match, manufacturing inconsistencies, directional bias etc. By all means, do the math and use it to design with, but always include a healthy skepticism about your numbers.
I've just used 128:1 in the past to make the math a little easier. I think we arrived at that number many years ago by hooking the motor and gearbox combo up to a charged battery and counting the number of Revs of the output shaft observed in 30 seconds. Then compared that to the specified no-load RPM and rounded off.
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I am not disagreeing that a buffer is required to accommodate variation. How much depends on what you are trying to do.
I am curious if we have the same gearbox with the rumbling about different motor pinions that I have heard. At least one
team claims to have received two different gearboxes in the same KoP.
In past seasons I have heard the FP gearbox provided anywhere from 122:1 to 144:1 so I was trying to take the additional steps to back up the numbers provided by including the spreadsheet.