Thread: Building a Aluminium I Beam Trailer

Originally Posted by jatt

Yeah ally can be a strange beast to work with.

Glad back when used to play with SS that I wasnt paying the bill!!!! One of my local steel merchants describes it as "drug money".

If you think ally is a queer beast, wait until you play with the various bronzes! Some of them merrily send a 16 pound persuader flying back at you without leaving so much as a mark in the bronze, while the ringing makes you feel like Quasimodo.
Dead right on the pricing of stainless. Few places sell by the meter, so full lengths rapidly drain the bank balance.

There has been quite a bit of discussion about alluminium trailers on the various boating forums going back quite some time.

There most definitely are issues.

NOW remember you are responsible for the engineering of the trailer for the life of the trailer....AND...you are under the legeslation required to be able to prove the enginering of every item.

When building in steel, the whole thing is pretty straight forward as there is plenty of "existing art" to compare with and pre-engineered parts straight of the shelf.

No way would I be atempting a trailer such as this without formal engineering input.

Then you have to ask yourself.."What do I expect to achieve?"

If it is corrosion resistance.....ya barking up the wrong tree there.....steel treated properly is very hard to beat.

Even if you use stanless, you have an issue with dissimilar metals..and because of the style of construvtion it is simply not viable to use the usual treatments.....even if you use a bucket of duralac....ya sill going to have issues.

as for weight......steel web truss construction will be far more predictable and easier to construct.

Then there is the cost.

cheers

Originally Posted by Karl Robbers

The ally beams will be well and truly stronger than your 100X50X3 steel channels. Channels are prone to twisting far more than a symetrical section such as a box or I beam.
Stainless would be required for your U bolt attachments in order to provide corrosion resistance.
I would be inclined to look at drilling the web of your beams to attach your mudguards. You could also make a S/S frame with your axles and springs mounted to it along with mudguards etc and u bolt this complete to your I beams. This approach allows the axle group to be slid forward and backwards to fine tune the balance of the trailer.
One word of advice with your Stainless U bolts, if bending them yourself, take care that the bends are not too tight as stainless U bolts can be prone to cracking. Also, lubricate the threads well when tightening any stainless fastener. If you don't, the bolt and nut will weld themselves together and lock up.

cheers Karl, since ill be using 130x80 i beam i was thinking of using 80x80 stainless steel 316 angle to U bolt under the i beam and attach the SS 316 spring hangers from also i would get a couple mud guard supports welded to the SS 316 angle, with the SS angle U bolted on it will allow the axle to be moved back and forth once in the right position i may bolt it into position

While I don't wholeheartedly agree with Soundman, he does raise a good point inasmuch as the ability to justify your actions at a latter time, even though your trailer has been certified by the registration authority in your state. Quite likely, you will need to show your inspection station that you know what you are doing, (in my experience most of them don't).
I did mention earlier getting some photos of proprietary trailers and copying their construction methods so as to have a baseline.
I have yet to see any aluminium trailer suffer a catastrophic structural failure, nor a steel one for that matter. I have seen numerous slow failures caused by poor design leading to ongoing cracking issues that are often very difficult to solve entirely.
I do agree that you need to identify your goals in the construction of this trailer and understand the potential costs involved. The moment you mention stainless your costs rise dramatically. I think I actually mentioned this earlier.
When you consider that a great many boat trailers are constructed from folded 3mm channel, I have no strength concerns with your chosen construction, section and grade of aluminium provided you can achieve a crack free bend in your channels.
You are talking a load of around 1000Kg. Your sections are massive when compared to the sections used for a quad dog body, (somewhere around 30,000Kg), if viewed in proportion.
I do still maintain my cautionary note as always, that you probably have easier and cheaper ways to build a trailer.

Hey Karl, ive priced main things so far like the

main chassis rails of the trailer $240 each x2 + $140 to bend it in 2 places each piece x2

cross members from here http://www.fab.net.au/rapidfab/Aluminium%20Prices.pdf 100x50x3mm 2 meters wide 8 meters all up $201.60

drawbar will be 100x100x3mm steel gal

stainless steel 316 angle is pricey will need to call up for this used for the spring holder and slideable axle

gal trailer kit from ebay $270

wheels $120

trailer lights $60

so far that $1411.6 minus 1 hour welding,draw bar, nuts and bolts,skids,winch, U bolts thats all about $400 worth, price that up against a new aluminium trailer of similar size $3000 on ebay cheapie from china, i end up building a trailer over engineered built from top quality products and i save 1/3rd the price

What about 304 stainless? Of course 316 is food grade.

As for the price difference, not sure to be honest. Being a food joint I worked at, I had little choice but to use 316.

Originally Posted by soundman

There has been quite a bit of discussion about alluminium trailers on the various boating forums going back quite some time.

There most definitely are issues.

NOW remember you are responsible for the engineering of the trailer for the life of the trailer....AND...you are under the legeslation required to be able to prove the enginering of every item.

When building in steel, the whole thing is pretty straight forward as there is plenty of "existing art" to compare with and pre-engineered parts straight of the shelf.

No way would I be atempting a trailer such as this without formal engineering input.

Then you have to ask yourself.."What do I expect to achieve?"

If it is corrosion resistance.....ya barking up the wrong tree there.....steel treated properly is very hard to beat.

Even if you use stanless, you have an issue with dissimilar metals..and because of the style of construvtion it is simply not viable to use the usual treatments.....even if you use a bucket of duralac....ya sill going to have issues.

as for weight......steel web truss construction will be far more predictable and easier to construct.

Then there is the cost.

cheers

when u get a "blue slip" (registration inspection) in NSW the mechanic does a engineer and design check they charge a small extra fee i think i was charged about $26.50 extra last time i upgraded springs on a unregistered trailer

Originally Posted by jatt

What about 304 stainless? Of course 316 is food grade.

As for the price difference, not sure to be honest. Being a food joint I worked at, I had little choice but to use 316.

i think the 304 is a problem with allow it must be 316 from what ive read, 304 is much cheaper so its a shame

For your application, I think there will be sweet all difference between 304 and 316 stainless as far as corrosion goes, but a hell of a big difference in price. The chromium content is the same, but 316 has 2% molybdenum added to enhance its corrosion resistance.
The worst scenario will be if your trailer is used in salt water and never hosed off, the best would be if the aluminium and stainless are electrically isolated, (rubber strips between them for example), and the trailer is used for fresh water only then hosed off regularly as well.
Thinking about it, even galvanised steel would probably work in your application although you may need to re galvanise the steel at some stage as the zinc will corrode preferentially to the ally.
Overall, corrosion should not be your biggest issue.

i'd be happy using galvanized steel for the stainless steel replacement if the gal was going to corrode first as its a lot cheaper throwing away $50 worth of steel than replacing the main aluminium frame costing $760

It would simplify the build somewhat in to the bargain.
A simple hose down will go a long way to keeping corrosion at bay in the case of a trailer that only sees intermittent immersion in a corrosive environment.
I recall when fabricating irrigation pipework some time ago, that we had a particularly time sensitive component coated with the same epoxy coating that marine piles are coated with due to the galvanising plant not being able/willing to pull their finger out. The coating was actually tougher than galvanising, (hit it with a hammer and the hammer bounced off), and was a fairly aesthetically pleasing black in colour. I don't know if this was the only choice of colour. Perhaps if you contact an industrial metal protection company a similar coating would also serve your purposes.

Something like this:

http://www.kbs-coatings.com.au/kbs-b...-chassis-paint

Or on a trailer like this:

http://www.kbs-coatings.com.au/diamo...on-information

I am thinking those are probably not the type of coating we used.
The coating was most likely a two pack product I am guessing. I do recall that we were told it could be laid on up to 3mm thick, so to me that suggests a product that sets fairly rapidly, sprayed through airless gear.
In all reality, the coatings you found would do the trick. After all, we are only talking intermittent immersion, hopefully followed by a freshwater rinse.

ive been looking at my option's and i need to budget in to hire a car trailer to pick up the i beams drop them off and pick them up and drive them home, couldnt find much about the NSW road and maritime on overhang for my little hyundai excel as i was thinking of sticking the 6.5m i beams on roof racks my car is 4.1m long

what are your thoughts on this? do u think the i beams will be too heavy to go on the roof at 27.5kg each per 6.5m length?

Originally Posted by gazza2009au

ive been looking at my option's and i need to budget in to hire a car trailer to pick up the i beams drop them off and pick them up and drive them home, couldnt find much about the NSW road and maritime on overhang for my little hyundai excel as i was thinking of sticking the 6.5m i beams on roof racks my car is 4.1m long

I think the rule is max 1.2m out the front, and max 60% of the wheelbase extending backwards, measured from the rear axle. Off the top of my head, I think 6.5m would be too long for your car.

UM.........building big ass trailer and talking about shifting big things with only a Hyundai XL......um am I missing something here?

cheers