Construction materials

[mechanicalbrain]

I'm curious about what everyone thinks is a good material for frame construction. If you have a specific please feel free to mention it. I'm more curios about the strength than cost.

[Cory]

Aluminum (Or if you're RAGE/571, wood )

Don't use steel. Ever. We did in 2002, for some insane reason thinking we would need the extra strength with all the robot on robot contact. Well, a frame made of 1 1/4" steel angle 0.125" thick ended up taking almost half of our allotted weight--with nothing on it.

Needless to say, aluminum would have worked just fine, and we would have had the weight for a lot of components that got scrapped because the thing was so darn heavy.

P.S. Perhaps you want to make this a poll.

[sciguy125]

Just like the commerical said: plastics make it possible. If it were cheap enough, I would make everything out of plastic.

BTW, what possible reason would they have to make those plastic propoganda commericals. Are there really enough people that feel strongly enough against plastic that they have to launch a propoganda campaign?

[Billfred]

Aluminum's done the job for 1293 on both robots.

Although that lexan splash guard we put on underneath the bubble maker (to keep the Victors and RC below nice and dry) does look pretty nice...

(By the way, this is why you shouldn't throw out all of those scrapped ideas immediately--that same piece of lexan was going to be a mounting board for electronics, until we changed the design on the arm. And an earlier version of our winch side plate became our extended battery holder.)

[mechanicalbrain]

Personally we didn't like our aluminum because it bent. It wasn't even at the joints it was the beam itself!

[Bcahn836]

Team 836 likes to use a combination of aluminum plate, angle and square tubing, plus 80/20. Very sturdy, easy to work with and tons of ways to use them. and for everything else lexan.

[jrocket567]

Its not the type of material you use, but how you use it... remeber those bridges you build out of 1/8x1/8 balsa wood and elmers glue that would weigh 50 grams and hold 50lbs?

[Bill_Hancoc]

If you want favorite material to work with as far as budget goes aluminum by far but if money was no object i would be using a titanium or carbon fibre. both of which have their disadvantages (titanium-dulls drill bits and other cutting tools fast)(carbon fibre-expensive and must be custom made for the most part)
So aluminum is easy to work with light and fairly strong.

[Cory]

Originally Posted by mechanicalbrain

Personally we didn't like our aluminum because it bent. It wasn't even at the joints it was the beam itself!

What type of aluminum were you using, specifically, and what was it used for?

[mechanicalbrain]

Originally Posted by jrocket567

Its not the type of material you use, but how you use it... remeber those bridges you build out of 1/8x1/8 balsa wood and elmers glue that would weigh 50 grams and hold 50lbs?

Yeah but a 1/8x1/8 titanium is going to work much better then balsa. However i agree engineering has a HUGE aspect on your strength. Also making frames out of carbon fiber is not as expensive as it seems.... But yes you do have to form it yourself (its not as hard as it seems). I probably should have included fiberglass too but i don't think anyone here used it.

[Andrew Blair]

Originally Posted by Bill_Hancoc

If you want favorite material to work with as far as budget goes aluminum by far but if money was no object i would be using a titanium or carbon fibre. both of which have their disadvantages (titanium-dulls drill bits and other cutting tools fast)(carbon fibre-expensive and must be custom made for the most part)
So aluminum is easy to work with light and fairly strong.

Titanium is not all it's cracked up to be, at least from a FIRST aspect. Its extremely strong, but so is steel. Titanium is is like 30% as heavy as aluminum. I can have the bragging aspect of making a bullet resistant robot, but if someone is coming into a competition and shooting my robot, I have more important things to worry about!

Check this PDF out: http://www.engr.ku.edu/~rhale/ae510/titanium.pdf

[mechanicalbrain]

Originally Posted by Andrew Blair

Titanium is not all it's cracked up to be, at least from a FIRST aspect. Its extremely strong, but so is steel. Titanium is almost twice as heavy as aluminum. I can have the bragging aspect of making a bullet resistant robot, but if someone is coming into a competition and shooting my robot, I have more important things to worry about!

Check this PDF out: http://www.engr.ku.edu/~rhale/ae510/titanium.pdf

However it does make painting your robot easy! You can anodize aluminum with a 6 volt battery and soda. Who wants to paint the Guggenheim red? Anyone? Wouldn't that be amazing! robots doing drive bys on other robots... except for the whole safety thing.... I'm just trying to picture a gangster robot.

[sanddrag]

Aluminum box tubing (square and recangular) has been the material of choice for 696 since 2004. Previously we had used Bosch 30x30 extrusion but then we realized that it was too heavy especially with all the corner brackets and fasteners.

I'd say if your base frame is more than 15lbs and it's not a crab drive, you need to rethink it.

mechanicalbrain, what exactly did you have bend and what were the circumstances under which it bent? Any pictures?

[David Guzman]

Please someone correct me if I'm wrong but I think you are not allowed to use exotic metals in FIRST which would include Titanium.

Also my team has used 8020 and .125 aluminum, but next year we are thinking box aluminum or 90 degree corners depending on the game.

Dave

[Cory]

Originally Posted by David Guzman

Please someone correct me if I'm wrong but I think you are not allowed to use exotic metals in FIRST which would include Titanium.

Also my team has used 8020 and .125 aluminum, but next year we are thinking box aluminum or 90 degree corners depending on the game.

Dave

They changed the rules.

You can use titanium, but you have to account for the price of it in your BOM.

$3500 isn't going to go a long ways towards building a robot, and buying Ti.