What is your aluminum tubing alloy? Pure aluminum is almost never used, and never for structural parts. Most mountain bikes were made from 6000 series with a T6 heat treatment or 7000 series.
Aluminum would be a pretty good material for buggy in terms of corrosion. It forms a protective oxide that prevents further corrosion. As long as that layer is no polished off the aluminum will only corrode very slowly. Contact with iron and steel should isolated to prevent galvanic corrosion.
A problem with aluminum is that is has no fatigue limit. So the frame is is going to fail, possibly with no visible warning signs. How fast it fail will be dependent on how deflection there is in use. I have not done a finite element analysis, but kite buggies may substantially higher loads bikes. I hope your tubing is fairly beefy.
Another problem with most aluminum tube sets is that they are typically large diameter, thin walled tubes. These tubes easily buckle like beer cans.
Heat treating is going to be problematic and possible expensive and most of the aircraft/ bicycle alloys require days at very specific temperatures to harden the alloy its full strength. This must be done after welding.
Making nice aluminum tube welds is an art.

Steel is way cheaper than aluminum. If weight is not a consideration, steel's higher stiffness per unit volume means smaller diameter, thicker walled tubes can be used: you can beat the crap out of it.
Stainless is not really that good around salt water. Around welds the corrosion resistance is much less. Chrome plating is a very bad idea for a buggy. If the chrome is scratched rust at the scratch will perforate the steel in no time.
If you want to chrome plate aluminum, you will have to plate it with something else first.
With steel you do not need fancy welding equipment. You can braze it quite nicely use oxyacetylene set up.
A few thoughts on aluminum buggies from a metallurgist. Good luck with your project.
Scudley

Hey scudley, Try 2x2x.250 and 1.5x1.5x.125 5086 alum ASTM certified Would that do it? I've been ridin my buggy for three years, flipped it , rolled it, cartwheeled it! No worries I check it all the time for stress cracks, so far none! Strength by design!

Quote:

Originally posted by WELDNGOD Hey scudley, Try 2x2x.250 and 1.5x1.5x.125 5086 alum ASTM certified Would that do it? I've been ridin my buggy for three years, flipped it , rolled it, cartwheeled it! No worries I check it all the time for stress cracks, so far none! Strength by design!

Excellent choice of alloy for the job. Hard to find out here, most of the stuff at the local metalmart is surplus from the aircraft industry, 6000 7000 series alloys. All your welds with 6000 and 7000 have to have Post Weld Heat Treatment, PWHT or it is like pasta. Using thick walled sections like you did, rather than tubing eliminates the beer can buckling problem. 5086 is excellent in salt water except for SCC.
Withs sections like this your buggy must be as stiff as hell. You must be able to stand in the middle and not see any flex. This is way beefier than mtn bike tubing.
How much was the aluminum? You bought from those guys in Norfolk, 24 ft sections.
If you bent this stuff for your frame, what the hell did you use to bend those sections?
It sounds like you did your planning rather than lucking out and getting by chance one of the few al alloys that keeps its strength after welding. It was not just some tubing laying around.
Are there some detail pictures of your buggy about?
Thanks for reminding us all that we should all regularly check our buggy's welds for cracks, home built or store bought. A friend found the cracks in welds of his front forks. This was on a fairly new name brand buggy. Nasty to drop your front wheel in a race.

S

p.s. 5086 is excellent for anodizing. Have you thought about colour?

I'm a navy contractor,so I got connects.Everything meets or exceeds Mil- spec. Have access to lots of drops from the saw;-).I did not bend anything ,it is all open root mitre joints. All two bead welds, no "rooticaps".We make shipboard exterior handrail out of the stuff.Stout material it is,but you gotta design it right too.

green machine

Do you find you get galvanic corrosion at the bearings and bolts, let me guess some voodoo navy grease to prevent it.
I figured miter joints would be the way to go or some big mother hydraulic press.
Do you weld for living?
S

I do not think you can anodize green.
With those tube sections, its fatigue life is going to be longer yours.
S

All 316 stainless axles and hardware, powdercoat rocks!I rinse it with fresh water when I get home. So far no corrosion to speak of. And when I was 18, I was building nuclear subs at newport news shipbuilding. I have been a shipyard and marine repair welder for 27 years.

Oh, yeah and I got some mojo grease called SUPERLUBE. It's great in bearings

Your product shows great craftsmanship. Your choice of materials superb. I think you have to agree that for the average schmuck, steel is probably an easier material to work with. Would you build a build a buggy out of 6xxx or 7xxx series tubing? I think it is too much trouble.
What does your buggy weigh in at?
I will take mine anodized amethyst.
Clearly you are a welding god.

S
I hope you have been really careful at work in those 27 years. That is a long time breathing fume and watching flash.

Thanks, I wouldn't use6000 or 7000 due to heat treat.5000 series is fine for this application. It ( the green one)weighs 65 lbs. Plenty of scrap and drop.Not for average joe build,and no unfortunately I have breathed aton of stainless smoke,7018,copper -nickle,aluminum,galvanized,oils,paint, and any thing else that will burn:flaming:

sick welder man what kind of welding do you do for a living. it sounds like ships or oil rig.

never mind weldgod i just read the rest of the post.

I don't know what series aluminum I have but its 2" round and probably .250" and its used for hand railing by the government in the water industry, you all think that should be sufficient? Its all pre-bent so I'll cut and weld to get the shape, I'll post pics of the alloy soon.
Thanx...

are there any numbers on it? i.e. 4043 , 5086 , 5056, 5356, 6061?

no!

My guess is... it's got to be strong enough, the #@%$#! is big and thick. I'm just in question of the abuse a buggy takes. I believe the weakest point is gonna be the welds, just because I'm not weldngod... I should get the welds good enough. Hopefully full penetration.

if its thick (3/16 "+) it will do. when you make up your weld joints ,clean them with flap wheel,and bevel pipe 22 degrees. Don't feather edge bevel, leave a little land. No more than 3/32" gap! put root pass then cover pass. It's stronger than you think,you need to make it strong by design. There are ways to reinforce high stress areas i.e.chocks, gussets,doublers,support brackets etc. things that need to flex can be built with natural arc to it . Ever notice tractor trailers that have aluminum chassis trailer, they have arch to them so when heavy load is put on it ,it will flatten out.Instead of buckling!If you use the right filler wire ,your welds will be stronger than the parent metal.

Weldngod... You are a "Weldn God"...:wow: Thanx Much!! You are an encyclopedia of weldn information!!

That's why they love my a$$, and put up with"wind's blowin today boss, later".;-)

Just Bought a PL folding from buggymangp and I should have it on 4-17-08 or hopefully b4, This will give me a good idea what is involved in a buggy and what design needs there are.

njoy, be safe(at least as safe as you can on a wheeled vehicle with no brakes,powered by an unpredictable force of nature that mankind has zero control over):frog: Be sure to post about your maiden voyage!

Take a chunk of your tubing to a local scrapyard and have them zap it with their gun . They will be able to tell you the exact alloy so you then know if it will suit your project and what filler alloy to purchase. Good luck and keep us informed.

Nice thinking...
Thanx, great tip!
Screwy

Quote:

Originally posted by torisspacedog Take a chunk of your tubing to a local scrapyard and have them zap it with their gun . They will be able to tell you the exact alloy so you then know if it will suit your project and what filler alloy to purchase. Good luck and keep us informed.

It does not matter,for a structural app. you would want to use 5000 series filler wire.You always use stronger filler than parent metal.If it was bought for hand rail it is structural grade. you wouldn't use the cheap stuff, due to liability issues. design it good,make your cuts accurate(no gaps),bevel, then weld it the best you can. I would tack it up real good 4 tacks per joint,then weld it.jump around alot so you don't pull somethin. Don't worry I'll be here to talk you through it!

Quote:

Originally posted by WELDNGOD It does not matter,for a structural app. you would want to use 5000 series filler wire.You always use stronger filler than parent metal.If it was bought for hand rail it is structural grade. you wouldn't use the cheap stuff, due to liability issues. design it good,make your cuts accurate(no gaps),bevel, then weld it the best you can. I would tack it up real good 4 tacks per joint,then weld it.jump around alot so you don't pull somethin. Don't worry I'll be here to talk you through it!

Thanx
You da man!!!

Going back to you question about seats - I've found that seatbelt straps looped over the frame and then epoxied with staples holding it together works great - I had a seat that lasted me for 10 months before I redesigned the seat and replaced the old one.

I also added a lawnmower seat that's made out of foam latex with a fake leather coating - the ultimate in plush rides - almost too comfy.

I'd like to see pics of that lay-z-boy bug your claiming...

Recently this project got a "NABX" defibrillator jolt... and the heart is pumping...

I'll kinda get you up to speed...

1st I started looking for a GTAW "Tig" welder to weld aluminum and at one point was ready to buy, then started having the whole "am I getting the real deal" 2nd thoughts and then decided to go to collage to take some welding classes... "NOW" I know what welder I want and feel a lot better about my decision (by the way its a Miller Dynasty 200DX)... and I feel I'm excelling at an extraordinary rate in my welding skills, YAAAY!!!

Now to the meat... I've got virtually all my materials and a lot of the parts are cut and drilled and close to welding still got some bending to do (basically the side rails and top fork plate), need to mock up the goose neck then cut and weld it... but all-n-all it seems to be on schedule for NABX...

The bug that I'm designing is inspired by Popeyethewelder's array of fantastic designs (Thanx Popeye)... I'd also like to give credit to weldngod for all the inspiration to attempt the aluminum buggy, to be a good welder and learn the correct way to weld...

Here is the mock up of the front forks (the top plate will have the sides bent down similar to PTW's new style forks), note the fork legs are not cut yet and will be cut when the majority of the main bug is mocked up so I can get a better idea of the length (hopefully this next week)...
Fork mock up...

This is a side view of what the fork leg should mock up like, there is a planed steep angle to be cut at the bottom of the leg to give it some style, also a slight angle at the top to accommodate the top fork plate that will be bent slightly down...
Side view of fork leg mock up...

These are the side rail to rear axle attachment brackets...
Rear side rail connection brackets...

This is a SCREWY spindle... I'm not going with the standard 20mm bolt axle... But instead I'm going with a beefy 3/4" chromeoly tube axle that will suspend in a 1 7/8" aluminum housing for strength... I also believe I should get smoother bearing rotation being a lil larger and plus hoping for a lil longer life and a higher load capacity...
SCREWY Spindles...
Second View SCREWY Spindles

I'm posting links to the photos as it helps the thread to open faster...
So excited!!!:wee:

Stayed tuned the next 4 weeks, should be exciting with as many update's as I possibly can...
Please give any comments, they are greatly appreciated and help in my progress...

I know this is stupid but this is my 420 post...

screwy my brother, good luck w/ your welding. Take your time, and don't overheat it. What kind of tig torch are you gonna get? I highly recomend the Weldcraft WP-20 water cooled. I run it regularly , at well over 200 amps for hours at a time. Only cost about 125 bucks. The remote is what will kill ya', they are like 180 bucks. good job takin welding classes, hope they were worthwhile. If you build a sweet a$$ bug , then it will be worth it. let me know if ya got any questions , and I wanna see a set of cans. It's all about heat input and the control of it.