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Unread 25-03-2009, 19:25
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sdcantrell56 sdcantrell56 is offline
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AKA: Sean
FRC #2415 (Wired Cats)
Team Role: Mentor
 
Join Date: Jan 2006
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Re: Wood Chassis vs. Kit Frame

As someone who has now designed and built 2 wooden drivetrains, I will have to refute almost all of your claims.

A wooden chassis is without a doubt lighter than a similarly strong aluminum chassis. The plywood we used had a density of .016lb/in^3 and baltic birch has a density of .023lb/in^3 in comparison aluminum has a density of .098lb/in.^3. This alone means that our chassis can have 7 times the material of an aluminum chassis for the same weight. Our chassis did not have 7 times the material but it did have significantly more which made the frame much stiffer than a comparable aluminum frame. Also the way it was constructed, with no screws and all tongue and groove joints, completely joined with epoxy creates a much more rigid structure. The one property that wood suffers in is the resistance of dents, aluminum being much denser will be able to take more direct hits without gouging. However in a game with required bumpers this is a non factor. Just as an example, our complete drivetrain this year with 6 wheels, 4 chains, and 2 cims plus transmissions only weighs ~33lbs.

Wood is much easier to machine, it is softer and easier to cut and drill, it is also readily available and much cheaper than aluminum (with the exception of exotic woods).

You can customize a frame out of any material you want. All that customizing requires is a design to suit your goals. Our frame this year was completely designed in CAD and then laser cut and epoxied.

Another nice property of wood is that it does have some inherent "give" in it. When wood is impacted it will flex slightly and return to its original shape. Aluminum does not share this trait. Also aluminum has a very finite life cycle, after being bent enough aluminum will snap. Wood has a nearly infinite life cycle.

As far as being cool looking, I will let these pictures dispute that claim.

Needless to say I along with the students on our team have fully embraced wood and really do not see any reason not to use wood in the future.

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo...eat=directlink

http://picasaweb.google.com/lh/photo...eat=directlink
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Last edited by sdcantrell56 : 25-03-2009 at 19:29.