Cold weld aluminium or steel?

[Helga]

Hi, I'm doing a little repair on the back of my VW car - a mk2 polo, just filling a small hole and though I'd cold weld (with something like jb weld) a plate on. However, I am not sure whether to use steel or aluminium... it will have to be shaped slightly plus won't be able to treat the reverse when it's done.

Any sugestions?

Note, I know proper welding is better, but can' afford it and can't do it myself...

[Helga]

Or indeed, should I use aluminium mesh and fill out with fiber glass / chemical metal?

[kevtherev]

A good mig welder would fill a hole without distorting the panel

it's all about heat.. or lack of it

[Helga]

Yes, of course you are right... but can't afford a mig welder, can't USE a mig wlder and at the moment can't afford somebody else to do it!

[Helga]

Oh bum... by cold welding I meant gluing!!! With metal glue like jb weld... not vacuum welding as I've just realised cold welding is!!

[jamesc76]

weres the hole ?????

[Helga]

The inner skin of the boot, and a little of the outer skin, is rusted through... I'm in the process of cutting out the bad metal... with a little dremel

[Mr Bean]

The inner skin of the boot, and a little of the outer skin, is rusted through... I'm in the process of cutting out the bad metal... with a little dremel

Poo! I hate those Dremel things even for model making and I do plenty of thaat. You really need to get back to good metal and I ain't not ever seen a Dremel type gadjet which will deal with that sort of job. I have used the following: Machine hacksaw bladeground to about a 30 degree chissel and knocked along with a hammer, Electric Jig Saw with metal cutting blade and oil, 4 1/2" Angle grinder with 1mm cutting disk, Pair of curved jaw tinsnips, Hand or machine nibbler. Nowadays stuff like aluminium mesh, fibreglass, pop rivets and the like are a bit iffy on bodywork repairs but Last summer I saw a badly rusted wheel arch passed in an MOT (not mine) simply covered with gaffer tape so as to protect a jagged edge. I guess though if it isn't close to a suspension point or seat belt mount you may get away with it. It'l probably be back to haunt you next MOT though.
Good Luck
Wolfie
I haven't seen a concrete sill for a few years !

[Helga]

I don't think it will ever be a real MOT issue as the damage is inside the car, not visible from the outside - actually my dremel with a good mini cutting blade cut out the rust quite nicely... slow yes, but easier than hammering I imagine. As for fiberglass, not as good as metal perhaps... but some cars are MADE of fiberglass... and so I can't see what the difference is really? As long as ALL the rust is gone and the clean metal encapsulated BEFORE I fill it up, I'm sure it will be fine... in fact it's a bit of an experiment really... see if 20 quids worth of DIY materials and several hours work can do, on the surface, what, on average, 350 quid would do at a local welders... and they are people I trust!

[CovKid]

I think if they did charge you £350 you might have a point but I'd have thought £10 or £20 at most. Sure you can fill it that way if you wish (nowt wrong in it) but agree with others it won't be permanent. Different materials expand and contract at different rates and ultimately you tend to get cracks and the same problem all over again. I have a rust spot on the tailgate myself. For now I just vactan it to keep it at bay but will put a proper piece of steel in there as soon as weather is warm.

[Helga]

Ah, 10 or 20 if it were just a 'plate' needed - but the whole back panel is a mess and needs cutting out, and the place I took it to is a proper body shop bloke who would fabricate a whole new back piece... have a look:

[Helga]

I suppose it IS better to try and find somebody else to weld it - but it isn't a T25! So doesn't need to last for ever

However, if somebody knows a welder who would do this sort of work roundStockport for 10 -20... or something a lot less than 350 PLEASE let me know before I apply the fibergalss!!!

[jamesc76]

if thats the door why not just get another from a scrapy ???

[Helga]

It's not the door, it's the top of the 'number plate' panel at the rear...

[CovKid]

By the rust marks on the inside, I'd say a substantial leak has caused this. Looks like the piece could be fabricated ok although I agree, hunt for a better example if you can. Otherwise if you're not intending to keep vehicle forever, clean up the rust and use glass fibre.

Other option is to make the section up yourself out of sheet steel and find a back-yard welder who would weld it in for you?