[SerpentEagle]

Originally Posted by Thad House

You do not want the gears moving on the bearing. If that gear gets tilted it will now not be the correct center distance through the entire gear and won't run right. Coming from vex they are usually held in with retaining compound, and if you have to replace them it would be a good idea to use retaining compound to hold the new bearing in. We had to use a press to remove the bearings, and you really don't want to be able to do it by hand.

Ok, the reason I was wondering is because one of the gears is partially blocking some CIM mounting holes, so I thought one solution was to just pop out the gear and unblock access. Another thing to consider while designing next time.

Originally Posted by RoboChair

I would not use #35 chain for pretty much anything on a robot, it is heavy and way stronger than it has any business being on a drivetrain. Working load(not breaking strength) on #25 chain is 88 pounds vs. 199 pounds for #35. I'm not sure what the safety factor on ANSI chain is, but I know that the 6 CIM drivetrain we had on our 2014 robot used #25 chain(the heavier duty VEX stuff with thicker side plates) and required very little maintenance nor suffered adversely from stretching.

15 fps in high gear is slow, very very slow for a 6 CIM drivetrain considering you are likely to lose 10% or more mechanical efficiency, leaving you in the 13 fps range. Our 2014 bot was geared to a theoretical 22 fps and we measured our actual top speed at just over 18 fps(18% efficiency loss). We likely could have geared it a little slower and gotten our top speed a little faster, maybe 19 fps. So I know you can reasonably push the top gear 10%-25% higher, the only reason to keep it in the geared to 15 fps range would be if you need rapid bursts of acceleration to cover sub-20ft range movements on the field.

My rookie year was 2015, so I have pretty much no knowledge on games with defense. What would be a desired speed for such games and why?

Also, without any weight the gearbox is geared for ~19 fps, and ~15 fps with 120 lbs of load, considering that there are two gearboxes on the robot. However, now that you have brought up efficiency loss, I will have to edit my spreadsheet to account for these things as well as voltage drop. Thanks for bringing it up; next time I will aim for a much higher fps.

Originally Posted by Knufire

Also, I'd expect a 22FPS theoretical 6CIM drive to have massive brownout issues on the RoboRIO without some sort of current management in the code.

Yeah, when I was experimenting with different gear ratios I found out that gearing so high resulted in almost 50%+ efficiency loss even with 6 CIMs on the drivetrain.

Originally Posted by RoboChair

Gearing for an actual speed of 15 fps after losses would be a better idea to take advantage of all that power I feel. Gearing for 15 fps theoretical with 6 CIMs just seems like a waste of 2 horsepower(1500 watts) to me, you can do it with 4 CIMs.

I think I may have miscommunicated. When I say theoretical, I mean the theoretical speed after robot weight, torque loss, etc. though I have left out things like efficiency loss and voltage drop.

With 4 CIMs, according to my spreadsheet, I get around 2 fps less speed on high gear. I know that 6 CIM drivetrains don't have as much improvement as lets say a 2 CIM to 4CIM, but I assume that acceleration and pushing force is a big component to games with defense. Again, according to my calculations, a 4 CIM drivetrain would lose almost 300 inch-lbs of tourque on low gear when compared to a 6 CIM with my setup.