View Single Post
  #24   Spotlight this post!  
Unread 26-11-2008, 20:28
Travis Covington's Avatar Unsung FIRST Hero
Travis Covington Travis Covington is offline
Engineering Mentor
FRC #0254
Team Role: Engineer
 
Join Date: Oct 2001
Rookie Year: 1998
Location: San Jose, CA
Posts: 574
Travis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond reputeTravis Covington has a reputation beyond repute
Send a message via AIM to Travis Covington
Re: 4 inch Wheel of Doom

In 2008 and 2007 we had identical wheels, however, the 2007 wheels were 7075 (and were optimized to utilize the stronger material) With the required bumpers in 2008, we performed another analysis and deemed the 2007 design "good enough" if we just used 6061. I should note, however, that we did have one of our 2008 wheels bend ever so slightly (still usable), when the 2007 wheels held up to much more abuse with no bending.

Also, from my past research, I couldn't find 7068 bar in any sizes large enough to make wheels. Granted, I didn't look for plate, but what I did find was all pretty small. Did you guys acquire something large enough to do the wheels?

And again, to reiterate what everyone has said so far. You should expect your design to change dramatically when using a stronger or weaker material. With a higher strength material, pockets can get way deeper, web thicknesses can be reduced greatly and you can save a ton of weight if you optimize the design and remove material in the right places. It sounds like you've done that already. As a next step, you may just do some more research to see just how strong some of the plastics are versus the materials you have used thus far and have available to you. Strength to weight ratio is the key thing to look at here, and 7068 is near the top of that list if you are only concerned with the strength (ignoring elasticity, fatigue stregth, etc)
__________________
-Travis Covington

2008-2017 - Engineering Mentor of Team 254
2001-2008 - Engineering Mentor of Team 968
1998-2001 - Mechanical Director/Driver/Member of Team 115

Last edited by Travis Covington : 26-11-2008 at 20:35.
Reply With Quote