Why don't more people use Al tubing? Granted its harder to weld, somewhat but if you want it strong and light, this would seem like a slam dunk here.....

Well for one thing. In order to match the strength of chromoly, aluminum tubing wall thickness would be so thick it would be as heavy or heavier than chromoly.

Aluminum isnt that much harder to weld than chromoly (if you know how to weld aluminum) but with material that thick, WOW! What a job.

Are most buggies being built from chromoly? The one's I've seen have been just mild steel with DOM type tubing ranging from .083 wall to 0.25 depending on application....I've seen maybe one chromoly vehicle but it was a dragster....one of my buddies is building a sand dragster out of Al because we got a steal on various tubing that would be needed, all for well less the $100 and will have enough to build several vehicles but I wanted to know why people use mild steel dom over AL tube, it should bend just as easy if not easier.....

Aluminum cage work is not allowed by any sanctioning body, that I'm aware of.

I guess if you don't mind having a very thick cage, it could be built equally safe, but you could never compete in ARCA, etc.

what about bending it? I don't think its as easy is it?

yes it can be bent very easily, but it is also harder to weld if not praciced, plus it is much mre expensive

aluminum tubing is strong because it is heat treated, once you weld it, the weld area becomes much weaker for example if you had some 6061 T6 tube the yield strength would be about 40KSI same balpark as 1020, but in the weld and HAZ the yield strength goes down to about 8 KSI or 1/5 the strength of the 1020. You can work around this with some cleverly designed welded joints and gussets or you can have the whole chassis heat treated, but good luck finding someone to do that. also aluminum is about 1/3 the stiffness of steel, and it does not have a fatigue endurance limit. My advice would be, use a real metal. Aluminum is great for some applications though, like transmission cases and engine blocks etc.

I will apply my mountain bike at a ski resort logic this topic.

One day we were at northstart riding the chair lift up the mountain.

we turned around and our bikes were gone.

they fell of the chair behind us and went went clang crackle bang on the ground.

One was an aluminum bike and one was a chromoly bike.

Guess which one was fawked up beyond use, and guess which one only bent it's aluminum handle bars and rims.

You guessed it

The aluminum fram with all it's wonder pretty much was destroyed in the fall. some of the tubes cracked in half litterally.

I'd rather be in a high speed rollover in a steel cage then the best aluminum money can buy any day.

Originally posted by coyote
Are most buggies being built from chromoly? The one's I've seen have been just mild steel with DOM type tubing ranging from .083 wall to 0.25 depending on application....I've seen maybe one chromoly vehicle but it was a dragster....one of my buddies is building a sand dragster out of Al because we got a steal on various tubing that would be needed, all for well less the $100 and will have enough to build several vehicles but I wanted to know why people use mild steel dom over AL tube, it should bend just as easy if not easier.....

Ahh, you said "buggies and truggies" I thought you were talking about class1 and trophy trucks where chromoly is the choice of material.
But the same issues apply to rock crawlers as well but you are right. most crawlers are using steel tube. Here are some #s


ALUMINUM TUBE
2" OD 0.250" wall 1.616 Lbs/Ft. 40,000 PSI yield strength.
4130 CHROMOLY
1.5" OD 0.080wall 1.820 Lbs/Ft 66,000 PSI yeild strength.

You would need to use a low strength aluminum if you are going to bend it or anneal it then bend it. After that you will need to have the whole thing heat treated again. Aluminum has 3X as much flex as steel so it would make for a really weird feeling rig.

My school built a race car out of Al. They had to have the whole frame heat treated afterwards, and many people didn't like the overall result. The biggest problem with Al is that it is very suseptable to fatigue. On a rockcrawler, just think how bad that would be.

Erin

aluminum crakcs - steel flexes

it is all about fatigue limit

all the other problems I think could be worked around

I think it dependes on the type also..

Almos every alumminum mountain bike that first came out cracked - steel would bend

BUT the aluminum bikes were tons stiffer

so I dunno though becuase they make airplabes out of alluminum...

whateva - tell me what you find out - I gotta lot of beer cans!

Ramstein thanks for keeping the data and facts but please remember that everythingthig that flies is al and stress data means something but not everything if the two weights are half as equal, just look at stee versus the same weight,......

I asked this same question a while ago and couldn't get a straight answer(I can get alum tubing through my work for free) but like Dean said you do have to use weaker alum in order to bend it...otherwise while bending it just snaps after about 10-15 degrees...another thing with alum is when bending you dont get as acurate bends because it always flexes back a little bit...this is from a ton of experience with bending alum for our boats(which the alum works great for)I would avoid the alum honestly and stick with the norm when it comes to your safety and your life:D

Bonding of Aluminum pieces is where some progres is being made. We can have strong frames out of aluminum but hey are more rigid and fail instead of yield under high stress. Not exactly spec'd to our sport.

Airplanes can be made of aluminum because they are actually engineered with lots of testing, data and meticulous manufacturing. Rock-crawling or any off-road racing for that matter is far form being really engineered, so the extensive use of aluminum is a ways off.

Originally posted by GOAT1
Airplanes can be made of aluminum because they are actually engineered with lots of testing, data and meticulous manufacturing. Rock-crawling or any off-road racing for that matter is far form being really engineered, so the extensive use of aluminum is a ways off.

Bingo!!! If someone had the money Boing does to builld a rockcrawler we would see some amazing peices, I'm sure some out of aluminum. Most of us just don't have the time and money to find the limits of what we can get away with.