Joint for angle-iron cage - 3-way mitre?

[MWAD7]

The project that is driving me to learn MIG welding is to restore (rebuild actually) the body of a 3/4 tonne military Land Rover trailer.

The construction appears to be a frame made of angle ‘iron’ with flat panneling. The project trailer is so rotted out that details such as how the corner joints were done are lost.

So, two questions....
Firstly, for the corner joints of the frame, is the easiest approach to do three-way mitre joints, or is there a better way (it would certainly be easier for me to cut thes than a three-way coping joint).


Secondly, when the panneling is welded to the angle-iron frame, what’s the best way to prevent (or reduce) corrosion between the hidden faces of the frame and panels - or will I just be relying on continuous seams of weld from letting anything in?

Thanks!

 

[frank horton]

jointing, depends how much time u've got to spend ???? also if u relace everything will it be a rebuild....????......grandad's broom comes to mind.........no offence intended........
as for the panels, if ur not bothered about originality I'd be using something like Sikiens panel stick and seal........easily paintable and whats used in industry today.....look at special bodied trailers and trucks.......
basically it's just an adheisive that sticks the panel to the frame bit like extra special silicone......and NO u can't use silicone.........
u won't get the panel off, other than cutting it off...it's very similar to how they stick windows in aeroplanes.......it's that good.........
so weld up and use a decent undercoat (I'd prefer 2pack) on the frame then stick the panels on.......u can use pop rivets to hold it in place while everything dries or for looks use a round head rivet evey 9"......just an idea...
hope this helps........Frank

 

[Wildefalcon]

Try the military lightweight forum, there's a section on trailers there.

 

[MWAD7]

Thanks Frank, interesting idea. And yes, in my mind it’s a rebuild (rather than restoration) given that I’m starting the body from scratch.

I’m already a member of the Sankey trailer forum, Wildefalcon, thanks. Ignoring the specific project, just for a second though, what would be the suggested type of corner joint for an angle-iron frame....

...particularly (bearing in mind my practice piece this afternoon - a mitred 90 degree, single-plane corner in box section with a sheet welded to one side) in terms of achieving 90 degree corners. I clearly need to work on this - despite tacking my joint near the outer corner and persuading it, slightly, to 90 before tacking elsewhere, I still ended up with a slightly acute internal angle...

 

[AndersK]

Whatever mitre design you choose a fixture is good help tacking them.

Stronghand 3D vices are expensive but
this is a simple and cheap design, just 3 plates with notched corners carefully welded together.

 

[Nomad]

I made a 2D frame from angle a while ago, simple to do and the end result was neat but doing something similar (with decent strength) in 3D would be difficult. Maybe 2D frame for the bottom, then weld verticals on the outside?