Bolt Together Aluminium Trailer Legal in NSW?

[gazza2006au]

Hey Guys

Looking for advice if anyone in NSW has a registered bolt together trailer be it a boat or box trailer? I'm looking to build a aluminium trailer i was going to cut and weld the trailer but than i found a guy online that had bolted a entire trailer together just wondering if i would run into any problems registering it in NSW

Cheers

[Noelm]

Lots of new trailers are bolted together, the Telwater Aluminium trailers are a combination of alloy I beam, and steel cross members, bolted together.

[bluefin59]

Lots of new trailers are bolted together, the Telwater Aluminium trailers are a combination of alloy I beam, and steel cross members, bolted together.

The cross members are box section alloy as well as I have one under my bluefin now and seems to work a treat , the draw bar is gal steel still as are the brackets that hold everything like skids and rollers . Matt

[BM]

I do wonder whether bolt together allot trailers will over time flog out the holes where the bolts pass through due to the relative softness of the alloy and the loading placed on those points as the rig bounces down the road.

[Chris Tucker]

I do wonder whether bolt together allot trailers will over time flog out the holes where the bolts pass through due to the relative softness of the alloy and the loading placed on those points as the rig bounces down the road.

i wouldn't worry about it. They tend to fail by the flange cracking off the web adjacent to the bolts a long time before you note any hole enlargement.

[Noelm]

Yep, the "flange" is pretty small on the I beam, I think Telwater bolt to both sides, kind of wonder why they don't make some sort of clamp gizmo to hold it too? but then, seeing as they make hundreds of Aluminium boats, why don't they just make a full properly designed and welded trailer? Those plastic (like Polycraft boats) trailers never really took off, I have only ever seen two of them.

[gazza2006au]

I actually have two plans

plan A would be to use flat horizontal plates at the top and bottom of each joint this will be all bolted together

plan B weld vertical flat bar to the ends of the cross members than bolt these flat bars to the main frame rails

which option would u guys go with?

its only for a 350kg tinny

[Noelm]

A small tinny, you could use either method, or a dozen other ways too.

[gazza2006au]

This is the boat a vintage 4.3m alloy tinny the hull has to weigh around 150kg its light as piss, plus a 25hp motor and around 5-10kg of fishing gear

the tinny just had a new keel welded on by me so hopefully she doesnt fold in half!!! :o ;D

this is also a plan I'm considering

[Chris Tucker]

If you're welding anyway, why not just weld the whole trailer? The thing to remember when building aluminium trailers is to engineer for stiffness not strength. A given ali section with flex 3 times as much as the same section in steel. The good news is stiffness goes up with the cube of the height. so you only need a 50% taller extrusion to get more stiffness than the equivalent steel extrusion. As ali is 1/3 the density of steel you'll still end up with a lighter corrosion resistant platform.

[gazza2006au]

If you're welding anyway, why not just weld the whole trailer? The thing to remember when building aluminium trailers is to engineer for stiffness not strength. A given ali section with flex 3 times as much as the same section in steel. The good news is stiffness goes up with the cube of the height. so you only need a 50% taller extrusion to get more stiffness than the equivalent steel extrusion. As ali is 1/3 the density of steel you'll still end up with a lighter corrosion resistant platform.
I can't weld out of position mate or it turns to rubbish so if i build the trailer like in my plan i can put pieces on my work bench and weld away in a comfortable position

I'm not sure if I'm up to the task of tig welding or if i should just glue it with the mig

going to hopefully pick up the supplies tomorrow as long as the steel shop can cut the aluminium i beam in half

[Noelm]

Probably easy enough to do all welds down hand, just a bit of messing around turning the frame, but it won't be too heavy to man handle!

[Lovey80]

I'm not the best off hand or upside down either. Managed to full weld and fish plate my off road cat trailer by flipping it each time welds were require on that plane.

[gazza2006au]

I'm not the best off hand or upside down either. Managed to full weld and fish plate my off road cat trailer by flipping it each time welds were require on that plane.

Did u have to deal with any warpage?

[gazza2006au]

I picked up the aluminium for the main outside rails and cross members, i have never bought aluminium like this I beam before and that is a solid piece of material!!! :o this trailer is going to be way over kill

i have decided to only weld the bend in the outside rails, the cross members will be bolted on like this http://www.ausmarine.biz/product/seatrail-aluminium-4-6m-boat-trailer/ one bolt on the outside of the cross member and a U bolt on the inside of the cross member

does anyone know where i can get custom stainless steel U bolts made up? or even if there is a way of making them my self that would be handy

[Noelm]

You could buy some stainless threaded rod and make them I guess.

[Force3]

Stainless steel is not a good option when in contact with aluminium. Add in salt water and you have a battery. Gal U bolts are a better bet as gal active element zinc is close to aluminium on the galvanic corrosion chart and 316 stainless is at the opposite end of the chart.

[gazza2006au]

I ended up welding 70x4mm sheet/plate on the ends that will be bolted to the main rails, i called a local shop asking about the stainless steel U bolts it was going to be far too expensive somewhere around $200 to have them custom made

tomorrow i will cut the top and bottom of the I beam and hopefully bend it in with some tie down ratchets

[Lovey80]

Did u have to deal with any warpage?

Not really. I was really over conscious of warping being my first ally trailer build. I first tacked everything in place and ensure square. Then I would do stitches in each section about 25mm long rotating so that each weld was as far from the one I'd just done as possible so it had time to cool. Once I'd stitched on all planes I went back and full welded in between the stitches. Where major structural beams joined with a fillet weld I flappered them back flat then added a fish plate over the top of them. Obviously my build was far more heavy duty than what you need (or I needed in fact).

the build thread is here: http://www.ausfish.com.au/vforum/showthread.php/179661-My-Home-Made-Ally-Trailer-Build

[Lovey80]

Where did you buy the I beam? When I did mine I had to buy 500kg at a time to get it made up.

[gazza2006au]

Lovey, did u do a full cut thru your beams or did u cut thru the top and bottom than bend the middle? were your beams 6061 T6?

i bought one length of I beam from Capral at Erskin Park (Western Sydney) http://www.capral.com.au/

these beams are not cheap at $225 for 6 meters, Capral also has prices of all aluminium sizes and shapes if u register as does Edcon Steel (Western Sydney)

[Lovey80]

Lovey, did u do a full cut thru your beams or did u cut thru the top and bottom than bend the middle? were your beams 6061 T6?

i bought one length of I beam from Capral at Erskin Park (Western Sydney) http://www.capral.com.au/

these beams are not cheap at $225 for 6 meters, Capral also has prices of all aluminium sizes and shapes if u register as does Edcon Steel (Western Sydney)

My beams were structural channel welded back to back to make the Universal beams. I did I full cut through at the angle and welded then fish plated. If I were you I'd cut and bend.

[gazza2006au]

I was going with welded cross member but have since ditched that idea and gone back to the bolted trailer, it's coming along nicely, i plan on TIG welding the V cut/joints if i can get my TIG welder working otherwise it will be MIG welded with the spool gun

took a short video before the big storm just hit Sydney

trailer frame a little smaller because i am a cheap ass i skimped on material i didn't want to spend another $225 on another I beam to run the full length so just bought one length and used what i had on hand by cutting it in half

it's ok in a way if i downgrade my 14 footer i just need to cut the draw bar to suit a 12 foot tinny ;D

i plan on picking up the draw bar and spring hanger material tomorrow going with steel for these but i plan on buying a poly storage tub from Bunnings and cutting it into thin strips to place the poly between my steel spring and hanger and the aluminium frame (cheapest option stainless steel spring and hanger base i quoted at close to $200 alone)

https://www.youtube.com/watch?v=caZDW8zb7l0

[gazza2006au]

Got the draw bar and angle i went with both steel as I'm not quiet sure if a aluminium draw bar could handle it plus there would be no way to weld a load rated steel chain to the aluminium for registration purpose