Re: Wood vs Aluminum
 

i would choose aluminum because although it may cost more, it is easier to fix if bent than wood chipping...:]

Re: Wood vs Aluminum
 

^Totally agreed.
I have to lean towards trusting welds more than trusting screws or nails, when it comes to either assembling the lower flame, or when it comes to attaching upper frame pieces. Also, if you made it so the two frames would way the same, that would be some awfully thin and unstable wood. 3/4 inch square aluminum is plenty strong for most frames, and is very light.

Re: Wood vs Aluminum
 

I have used wood on 10 of the 12 robots built. The right wood works great. Due to the high impact it will take without breaking. Team 61 robot has been know to hit a lot of robots. But the robot frame has never failed. A wood frame works great to start from due to you can place any part on it with out a lot of work. Just pick a spot and put it there. where the Aluminum you need to do a little more work to make it fit.


Wood and the parts it take to put on different devices are cheap. The hardest thing with wood is knowing how to use it in the best way to get the most from it.

Re: Wood vs Aluminum
 

This is my first year NOT working with wood for a drive base, and I must say I don't really have a favorite.

Wood is, for the most part, easier to work with. With little to no resources you can cook up a pretty solid base in less than a day. Electronics mount up nicely to it, and you can even give it a slick automotive paint job. Beyond that, with the proper reinforcement you can slam the thing into walls all day and not have to worry about it bending or breaking.

Aluminum is a bit lighter, and more customizable. You can get some pretty unique shapes and work motor mounts directly into your parts.

I don't really see a big difference in terms of strength (for the purpose of a drive base) between wood and aluminum. Wood has the tendency to gouge, which isnt all that pretty, but for the most part it holds up quite well.

So, I guess its all a matter of personal preference and experience. YMTC.

Re: Wood vs Aluminum
 

Here are some useful properties of Birch (home depot grade plywood material, aircraft grade is void free with superior propeties at about 3X the cost) and 6061-T6 aluminum (all in KSI):

aluminum wood
tensile load at failure 45 10
modulus of elesticity 10,000 2,000

Here is that same table adjusted for density:

tensile load at failure 16.7 16.7 (ahhh perfection)
modulus of elesticity 3703 3333

Price of a clamp = $5, price of a square wave TIG machine = $1500. Home depot grade wood glue can acheive 80% parent material strength with much less skill then welding, and you don't have to heat treat glue joints for full parent properties. Anyone want to race me to install a new limit switch with 2 wood screws vs tapping holes? How about hand jigsawing 10 linear feet? With a rookie team (3rd in a row for me), 6 weeks, and no money, I got wood on the brain.

Re: Wood vs Aluminum
 

execpt honey-come aluminum... :D

Re: Wood vs Aluminum
 

Nice comparison!

although you can use a $1.50 clamp to hold an aluminum bracket on to an aluminum structural part too, if you design it right....no welding needed.

Re: Wood vs Aluminum
 

Well then you can use a 1 cent woodscrew to hold the wood inplace! Beat that!

Re: Wood vs Aluminum
 

No need to beat that, I was just trying to make the point that you can build a robot with aluminum with only hand tools, if you really want to. There is no need for a TIG welder.

Re: Wood vs Aluminum
 

My team actually has several peices of honey-comb almunium and I assure you it is far easily bent then wood.

We also have some honey-comb carbon-fiber, but its a real dog to work with...
Given the right grade and the correct tools you can make quality parts out of wood.

Re: Wood vs Aluminum
 

We've used wood on our robots before... It has just been hidden from the public eye.

Re: Wood vs Aluminum
 

Wood doesn't always look worse though. As Tom posted earlier, it can be painted quite easily.
Plus, some wood bots can look quite slick even without paint

Re: Wood vs Aluminum
 

I've worked with honeycomb as well. If the cells are unprotected or the face sheets aren't up to part, the cells can easily damaged, or distorted and bent.

From what I've learned (2 years interning in the satellite part of Northrop Grumman). You want to make the honeycomb and face sheets the right size the first time, and never try to cut or reshape it. But then again, my background is where they make every part custom and remake parts rather than adjust an error in a current one.

One time, I had to scrap a whole bunch of panels and once the face became distorted or bent, they lost all their strength. Sure was a fun day.


Back to Al vs. Wood. There doesn't seem to be a universal right or wrong, it all depends on the application. I tend to prefer Aluminum because my team has been able to beg and borrow resources to deal with it, but if we had less we would probably use wood a lot more.

Re: Wood vs Aluminum
 

aluminum is a lot stronger than wood is. also it doesnt swell when wet. (aluminum comes in handy here in hawaii)

Re: Wood vs Aluminum
 

i can tell you that one of our key parts this year is being made out of wood..... i'll post pictures of it after the season is over.