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Unread 01-08-2014, 10:35
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Adam Freeman Adam Freeman is offline
Forever HOT!
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: Jan 2007
Rookie Year: 2005
Location: Rockwall, TX
Posts: 497
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Re: paper: 2014 HOT Tech Notes

Quote:
Originally Posted by MrRiedemanJACC View Post
Adam, The step file looks great. Not so sure I'm glad I saw this, I won't be getting much sleep now!

It always amazes me how well designed your robots are and how you can push something right to the limit. The first thing I noticed is that you don't direct drive any of your wheels on the drivetrain. Is there a specific reason for that? Or do you just want to keep the weight of your Cims and gearbox centered?

Also, I am impressed with the 9 mm belts, seems like that is just too close to breaking, but I like that you were able to do that.

In the model it looks like you raised the outerwheels about 1/8"? Is that what you went with or did you need more and shaved the wheels a bit?

Thanks for posting this!
We've used this chassis setup for a couple of years now, so most of it just carries over from year to year. At the start we decided that it was easier to leave the gearboxes centered for packaging and CG purposes. At this point we are comfortable with the gearing and chain/belt routing that we've just left them there. It helps us get a jump start on the season knowing we can get a chassis design solidified quickly so we can move on to more game specific components of the robot.

We actually switched from the 9mm belts to 15mm belts after we broke a belt practicing before the season. We had quite a bit of practice time on that belt and only one side broke, so I would guess something might have happened to that belt when it was re-installed (we had just replaced wheels before it failed). We ended up using 15mm kevlar re-inforced belts to ensure that we didn't have any drivetrain issues. We had the space and weight, so better safe than sorry.

The only drivetrain issue we experienced this year was picking up some debris in the drive that flipped the belt over and shredded it.

We stayed with the 1/8 raise on the outside wheels. We didn't shave the wheels, but the turning performance did increase as the outside wheels wore down. We had some issues throughout the season with popping the main breaker, which I'm sure the turning scrub had quite a bit of influence.

Overall we weren't extremely happy with the chassis performance from an agility standpoint, getting out of t-bones, avoiding defense, etc. We will probably do a complete re-evaluation of the chassis size, shape, # of wheels for next year.
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