some slightly technical welding questions...

[volks_womble]

Morning all.

After picking up a pile of repair panels from schofields I am wondering what the best way to attach them is...

I will be doing a complete offside sill, and lower panel, two steps, two seatbelt mounts, sliding door inner and outer panel... at least for starters anyways...

I am reasonably confident with a MIG welder, although usually on rather thicker material than t25 panelwork.

My current thinking was to drop to 0.6mm wire (I ususally use 0.8mm) and us a spotting technique...

but I am wondering whether it might be worthwhile trying with TIG? I have access to a fairly substantial TIG plant, but have very little experience using it.

Does anyone have an opinion as to whether it would be worth getting to grips with the TIG for the thin stuff or whether to stick with the process I know?

Before anyone suggests it, Gas welding is also an option, but I am not a fan of the distortion created by the amount of heat required for gas...

Cheers
Mark

[what2do]

Blimey blimey blimey, you're in for some fun!!

Right then, make yourself a flask of tea and search for 'metal mickey'. You're going to need HOURS to digest his posts on panel replacement but trust me, he's bee at this malarky a while. 0.6 mm is the correct gauge but Tig is awesome at this kind of work. Bought myself a Migatronic TIG just so I can have a go instead of relying on the mig that I normally use. Less heat with the TIG and so panel distortion is less of a worry, having said that if you're careful, MIG is what most people including myself use with positive results. Sounds to me like you're spoilt for choice .

Ps. Between you and me, metal mickey is rather keen on seeing lots of progress photos. I believe he sees it as a way of paying him back for his contributions on here, but whatever you do, keep that to yourself and don't say I told you.....................

[boatbuilder]

I just did all of mine with the mig - if I were you I'd just experiment a bit with all three techniques, especially if you have easy (i.e. free) access to them.
There are all sorts of tricks with the mig. 0.6 wire is what I used. A bit of copper is handy for clamping behind very thin metal so it doesn't blow through. Then use the start stop technique and cut off the glob on the end of the mig wire before you start every time. And have the metal as clean as possible before attempting a weld. I used compressed air to cool the welds as I went, to try to avoid distortion. I made repair patches at or slightly below the original level because its easier to pull it out a bit or use a skim of filler than it is to whack in metal that's standing too far out.

[volks_womble]

Thanks for your replies chaps,

boatbuilder: Your build thread has been really very useful in terms of working out what I am letting myself in for! I am no stranger to rust repairs - usually on Land Rovers - but seeing the work and progress on yours has be fantastically helpful. I have also taken on board some of your product advice too - some of your comments on weld thru primer for example.

I am very tempted to invest in a blaster of some sort too. You seem to have made a lot use of yours!

what2d: I have corresponded with mr MM previously, and his words of wisdom have been heeded, and his threads studied! Given my familiarity with the MiG I am thinking that I will probably stick with that for now. I may well have a go with the TiG on some practice pieces and see if I can get is sufficiently good to make it an advantage...

Pictures will happen as soon as I get some time to actually start attacking the van with the grinder...

Another question: Joggling or not for panel joins? Thinking specifically on the Sliding door skin...

Thanks
Mark

[boatbuilder]

Haven't done that particular repair but I'd imagine I'd just use a separate backing strip of metal, drill some holes and plug weld it.

[silverbullet]

I always thought that gas was the lowest heat option? Mig and tig are so much hotter (white hot, not red) or so I was told by the commercial fabricators that I know.

[Plasticman]

gas may have the lowest heat in one way but if you dick about then the heat build up will cause issues, there is a knack to it and you use the distortion aspect to your advantage, cant learn it in college or a book sadly.on sheet work you can tack as quick with gas as mig,
but in the real world most folks dont have access to nor are able to gas it so mig is second best and suffices
oh and if your handy with tig then that works fine for certain areas, id question wether it would be nicer than mig,
mm

[volks_womble]

Problem with gas is that while the process is lower temperature, it takes time to get that heat into the material, which leads to distortion. With tig, the heat is higher, but almost instantaneous, thus less distortion.

If you have ever looked at the bluing round a weld - the heat affected zone - it is far smaller with tig, than mig, and much wider again with gas

[Plasticman]

you obviously havent done much decent gas welding. as you know i use it for the majority of body works as its the best way to get the results required, you have access to all three, use whichever is easiest and you have most competence in, as the result in most cases is what matters rather than the method. though i really do draw the line at joining panels by blobbing welds on the outside of the seam which i often see
mm

[volks_womble]

You are right - my gas experience is entirely limited to when I went to night school to learn welding some 10+ years ago - it was half gas and half Mig.... I really haven't touched it since! Mig just seems to work for me (and means I don't need to keep bottles of oxygen and acetylene at home, as it has a habit of invalidating your house insurance...)

I am going to go down the Mig route, using the diagrams you have shown for rejoining panels... and we'll see where we get to.


Mark