28 replies to this topic

[Shifty]

Yup, can only echo what Dave/jack/SoG have said.

When I do a full floor repair I generally lap joint it/joggle ie, and then weld from the top and undernearth, give it a light dressing and a bit of seam sealer and job done.

Ok, you can still see the repair but I don't like grinding too much weld off structural areas.

[minidaves]

well welding i remeber the hours when i was an apprentice how to stick weld, gas weld, mig weld, how to make a sheet of steel to turn into a cylinder when welding lines and it distorting.

there is talk in the trade that all mechianics are quailfied before working on any motor car, there is already some guide lines in the bodyshop lines

dave

[Senile Old Git]

well welding i remeber the hours when i was an apprentice how to stick weld, gas weld, mig weld, how to make a sheet of steel to turn into a cylinder when welding lines and it distorting.

there is talk in the trade that all mechianics are quailfied before working on any motor car, there is already some guide lines in the bodyshop lines

dave

So are you specialising more in the bodywork aspect of the trade these days?

[Rich.]

Ok, you can still see the repair but I don't like grinding too much weld off structural areas.

Agreed again. I genrally grind the top side or visable weld down as flush as i dare, usually still abit above surface, then ramp the edges with a flap disk, and genrally just skim the opposite side of the weld to make it slightly less obtrusive if anyone were to go looking around.

But people who make a repair and grind fully flush again have pretty much just removed the majority of the strength of the repair, obviously you should have penetration through the steel, however in comparison the weld sitting above the steel is what gives the joint the majority of its strength.

Rich

[Senile Old Git]

I think we all concur on this, but I do like to offer a spot of filler each side of the weld to make it look "seemless"

David Isopon .. you sir are a god! (if your product is used as intended)

[In-a-mini]

But people who make a repair and grind fully flush again have pretty much just removed the majority of the strength of the repair, obviously you should have penetration through the steel, however in comparison the weld sitting above the steel is what gives the joint the majority of its strength.

Rich

I disagree with this if the repairer is competent with both welder and grinder then there is no strength loss. i have had welds that i have done this way tested and the failure point was not where the weld was. but there is actually a stress point along both sides of a weld that is left and this is commonly where when tested they fail but still exceeds requirements.
Each to there own to finish a weld this way most of the time is in tacking up and careful grinding/beating. If i left all my repairs visible then my customers will not be happy and thats why the cars i do win awards.

It is much easier to joggle the repair and if you are happy with that fine i was just advising that repairs needed to be seam welded to meet mot standards .

[Rich.]

I agree that when the weld is external, on view, theres no other option. But on a floor plan with a carpert over the top i carnt see the point in weakening it just for the sake of it.

I know in theory a weld should be just as strong when grinded flush as a solid piece of steel is, yet it never seams to be. Wether this is down to the heat of the welding process causing weakness i dont know, but where possible i always tent to try and leave as much of the bead in place as possible.

Rich

[Senile Old Git]

When I bought my welder the local supplier suggested I bought this 285amp affair that was three phase, I could not understand why this was his recommendation as all we do is Minis, and the machine is bloody cumbersome. His argument was two fold, one 3 phase units are cheaper and secondly having a machine that is way more powerful than required gives you a multitude of power settings and variable wire speed options. These infinate setting allows a neat deep weld that prevent blow through

After using the machine for a few years now I feel I bought well, as long as the metal is clean it gives a clean weld that gives deep penetration and the weld protudes no more than 1.5 mm off the surface. Personally I found the "hobby welders" are just not powerful enough to cut the mustard.

I have to agree with Rich, a correctly welded seam should be virtually invisible, that is why we finish with a skim of filler, prime the repair and paint in body colour. Nothing looks worse when you lift a carpet to be greeted with ill fitting plates "welded" by Charle the pidgeon then slapped over with underseal.

[minidaves]

have to agree about hobby welders, and that gasless cack looks like gorrila snot when you try and weld with it, my welder is 195 amps single phase running on a 30 amp socket, because half the problem come down to the extention lead people use, most are a bit like putting the m25, down the a25, as in you can get enough power to where you need it quick enough. and welding requires power clean metal proper gas and knowing how to do it

dave

[Senile Old Git]

welding requires power clean metal proper gas and knowing how to do it

And a decent auto darkening welding helmet so you can see what you are doing.

[Rich.]

Yep, at home i run a 155a Single phase mig, on a trolly with proper gas and a 32a supply to it, perfectly capable of welding upto 6mm if needed. If i need more then its up to the dads company and bust one of the big 400a jobbies out, but to be honest whilst doing stuff in the workshop at home i have never needed any more than 150a, its seams about perfect and i can keep the trolly pretty small so i can still fit it easily through doorways and carry it up stairs with 2 people if i feel the need to. It still lets me get nice deep welds even on about 1/3 power on 1mm plate, meaning minimal grinding;



Rich

[gs.davies]

Nice weld there. I've also got to do that. Do I have to take the subframe out? I was thinking that by leaving it in place, gettng the bolt holes in the right place would be easier.

[Rich.]

ITs abit of both.

I took the frame out because i had to get to the boot floor aswell. However i had the problem that every sub frame mount was corroded/snapped/moved. So alot of it was positioning then checking angles and levels.

But basically yes, i took it out, then redid the rear bootfloor as the rear sub frame brackers are fairly obvious where they go and its quite hard to put them in the wrong place. Once i put there in i just kept offering up the subframe and sticking the 4 rear bolts in, and tacked the front mounts into place. The opposite side to this was ok as the rest of the rear heelboard (I think thats what its called) was ok, but on this side i had to replace most of the rear corner, hence why i welded the mount on like his instead of attatched to the heelboard.

Rich

[gs.davies]

Just tried my hand at welding... then the gas ran out just as I started to get the hang of it.

A trip to BOC is in order I think!