New to chassis welding

[joseff]

Hello all, what a great site! hope i've got the right forum.
Ive just recently aquired a small 4x4 that needs some welding on the chassis, Being new to automotive welding, I'm a little unsure which way to do it.
I would like to cut out all rust in a nice square/rectangle appature and weld in a new plate the same size and re-paint etc... so you dont see the repair. But some people say take out the rust and patch right over the top? What is the right way, is there a 'right' way?
How do you protect the bare metal on the inside?
also are there any laws/m.o.t requirements covering chassis welding?

Thanks for any comments.

 

[the snooper]

hi you have the right idea cut it out and make a patch to fit in the hole if you plate over the top then it could hold water between the plates
the rules regarding mot for anything structual ie repair plates is that they must be fully welded however if you were to replace a full sill then it can be welded as the original was
regarding the rear of you repair most people would try to get some waxyoyl in there via schutz gun with the cavity tube attached

 

[joseff]

Thank you