I am having a 24 ft flatbed gooseneck made of aluminum built.
We figure it will cost between $5000 to $6000 to build,
also figure it will cut 40% of the wieght but will settle for 30%.
Any comments.

 

Closely inspect the frame, etc. regularly for fatigue cracking.

 

what grade aluminum are you using?

 

We have to discuss that issue.
I am examining my current trailer and looking at tables in order to have a better understanding.
I will post the details as I understand them.

 

6061 series is a good structural grade aluminum. I'm not sure which heat treatment is the best for fatigue crack resistance though.

Aluminum welds are different from steel welds. Steel welds will be as strong as, or stronger, than the base metal. Aluminum welds are generally weaker than the base metal. That's especially true for a heat treated grade such as 6061. You can relate it to a heat treated tool that you've accidentally heated too much on a grinder or w/ a torch. The only way to make the tool tough again is to re-heat treat it. Same thing w/ aluminum, but it's a very complicated and time consuming ordeal that most welding shops don't even do. To get around the problem of soft welds, the joints are designed differently.

Let us know what you come up with! I'm always interested in welding projects!

 

Sounds like a fun project. But I wonder why? Fuel savings? How much will it save, figuring 40% lighter weight. To carry a 40% higher effective weight carrying ability? I dunno.

Again, I think it sounds like a cool project, but using the trailer as a work tool, I think I'd stick with something made of old fashioned steel. You never know when something will fail, and when it does, Murphy's usually riding shotgun with you when you're a long way from home.

Its those cracks that I'm thinking of - and finding a good welder to weld it for you when Murphy's messing with you.

Is there any difference in re-sale of an aluminum GN from a steel version? Will it give you your money back when you sell it?

We don't build our ships with AL superstructures anymore either - the flexing splits it.

 

I built one a couple of years ago from a wrecked 18 wheeler trailer. If you will look the side rails are constructed with welded joints. The rest of it is bolted together for stress releif. I'd look at one before I designed trailer.

Mine had an extruded side rail with welded flags iniside on 16" center to bolt a 4" I beam too. The outside of the rail had a tie and stake rail system as all flatbeds have. Might be the cheapest wat to build your trailer is to find a wrecked aluminum 48' trailer for you needs and salvage the remains.

I no longer have mine. I just sold it last month to buy a larger trailer. Jim

 

What bulabula and prosouth said sums it up pretty well,al. is kinda hard to work with. Have you thought of maybe useing main frame rails out of steel and then decking and crossmembers out of al.. Some of the floors in al. cattle hauling pots are real neat strong floors. How much weight are you going to haul? Good luck on the project, I've built several steel trailers and used to enjoy it till I got burned out. P.S. Have you priced metal sinse the chinese started buying it all.

 

I was running out the door to help Santa Claus (best friend) with his kids fourwheelers (Christmas presents) as I was posting the above and didn't get to finish, spell check or edit.

The frame of my trailer was 3 x 4" Tube and the Aluminuim cross rails were attached to them. I then screwed 3/16th" aluminum treadplate from the flatbed down for the floor. I had a 5" C-Channel A- frame tongue to the hitch to finish up with a 2 5/16" bulldog.

The Aluminum was actually a bed set onto a steel chassis similar to that of a roll back truck. jim

 

Bolting some of the most flexible joints sounds like a good idea. That way the joints would have the right amount of flex and play so the aluminum doesn't crack.

Trailers are actually made to flex a little bit as they ride down the road. The problem is if you flex aluminum too many times in one place it'll definitely crack along a weld. Careful consideration has to be given to the design of the trailer to prevent that.

 

Bolt everything you can, gusset everything you can't. As has been stated, in structural steel construction the weld is the strongest point, with aluminum you loose approximately 50% of the strength of the structural member from the joint to about 1" from the joint. That is one of the reasons you have to use larger size members with aluminum structures.

I would be supprised if the reduction in weight actually provides any long term benefit. People say that aluminum doesn't rust, that is true but steel doesn't corrode. You stop rust by painting steel and you stop corrosion by painting aluminum. Paint sticks to steel easier than it sticks to aluminum. You can guess what my preference is.

Good luck on your project. I will admit that aluminum trailers look very cool.

 

My trailer was 14' / 2'dove or a 16' OAL it weighed about 1200# with two 3500# axels and the 3x4" tube carriage with a 4" C-Chanel tongue, and 3/16" aluminum diamond treadplate flooring. (I incorrectly stated earlier it was a 5")

It had a set of Jeep aluminum wheels on it. Pulled good and was tough as any steel trailer I ever had. I built it to pull behind my Cherokee Jeep and needed the lighter mass of weight.

The problem is design, if you weld everything it won't last. If you bolt it together it's as good as it gets. The bed is about the extent of the aluminum usage. jim

 

all the aluminum boat trailer I have or had , has been bolted togther, . I went and looked at the one I have now , there is no welding on it
maybe there,s somthing to this???????
jman

 

For the most part you have no choice but to use 6061 for the extrusions unless you build you own angles and beams.

5086 is a marine grade of aluminum that has a much better elongation factor than 6061 and is not a briddle.

Welding aluminum with a standard mig set up can be difficult if the weather conditions are not
almost perfect. Cup distance from the work piece is also critical to keep from votexing moisture into the weld. Short choppy weld seems are the worst thing you can do. You need to run them seems out as far as possible before the stop and made sure you come out cold to prevent crater cracks that may become cracks later. Grinding the stop for the start is the best thing to do. Only grind when you need to. I've seen so many welders bust out because they used the grinder to much.

Good luck.

Dave

 

I'd consider designing it with steel for the main frame and hitch, mainly because there's a lot of bounce and flex between the hitch and the axles on a trailer of that length. Aluminum C's or I's for cross members and diamond plate decking would still save some weight and not be as susceptable to dangerous stress cracks. Another consideration is that each section made from aluminum would likely have to be taller than the same part in steel leading to increased deck height. Also I haven't followed aluminum prices closely the last few years but do buy steel every couple weeks. If aluminum has gone up at the same rate I'd be suprised if you could get the job done in that price range unless labor is nearly free.

It would sure look cool though, shiny is good