body work for a newbie

[cantankrs]

Hi Michael, I was in a hurry when I typed it. I was just writing that you should protect your wrists from undue shocks when trying to bend heavy guage steel sheet by holding the metal with one hand and trying to belt it around something solid to form a shape with a hammer in the other hand.

Also when I say 1mm gap then that's about what I suggest you aim for. I agree with the Scotty where he wrote

but you will need some gap

The edges expand together when heated and then will shrink a bit afterward but if no gap at all then the panel has to grow outward which isn't desirable. I've not really used the copper backing idea - sometimes you can't always get a backer in situ so it's best to learn so you don't have to rely on it. When I said turn the Mig up for tack welds, it's so you get 100% penetration from the momentary pull on the trigger. When you've finished tacking back the voltage and wirefeed off. You'll find the build up is high and penetration low as you start laying down a bead, and by the time you've finished your run the build is low and the penetration is high. Tricky to juggle this balance over short runs. And like Ken says don't grind off too much - or only grind off one side depending on how your welding shapes up. Everyone here is saying practice on same guage. I think 18 gauge is about 1.2mm so a nice gauge to work with.

You ask about body filler. Everyone has different ideas. Some fillers work better on bare steel and others over primer. Same for stop putty's. some people declare any filler is bad. On American Hotrod they cover the car in filler and then shape it down. You can lay tins of the stuff on ($$$) and end up with 99% of it on the floor as dust. They used to use a Lead/tin alloy for filler but its hazardous to health but then plastics got better. I try and get the steel work as close as poss and then as little body filler as I can get away with. I think filler and primer are hygroscopic? they absorb moisture so consider that. A faint overspray of a dark colour is sometimes used as a 'guide coat' before sanding so once you get stuck into sanding you can see the high and low spots in the primer or filler. Always have a layer of primer over filler before colour coats. Understand that I'm mainly discussing the single pack acrylic paints here. I've never touched 2-packs and single pack enamels generally need fewer coats than the old acrylic because enamel is thicker. But the basics are the same.

Oh and flap discs and sanding discs are good. Pick your grit size carefully (clogging vs damaging older paint layers). And rough your bare steel before applying filler if that's how you're doing it - to provide a key for the filler.

You might also consider a bare metal prep/etch but not sure that many people really know how to use it properly - me included.

Regards

Alex