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

[Geoff Winnington-Ball (RIP)]

Just a small point, but one alluded to earlier in this thread. When I was MIG welding a long time ago, I used both argon and CO2 and I found that the argon worked a lot better. It's more expensive, but gives smoother welds with less splatter. Welding sheet metal is tough enough at the best of times, so I concur with the advice to practice, practice, practice first! When you're confident you can do it well, then go for the real thing.

Let us know how it works out!

[Phil Waterman]

All of the tips points given are what most experienced welders would tell somebody starting out. The most important tip of all for the new vehicle restorer though is Ken's practice.

It can not be over stated DO NOT start on the part you want to use.

Start with scrap bits and keep practicing until you can produce the kind of weld on junk that you want.

Cheers Phil

[Keith Orpin]

Two of the best tips so far mentioned are the use of Argon as opposed to Co2, as Argon is not as "cold" as Co2 when welding ( if you are feeling really flush try Aztec 25, which is a mixture of Methane/Argon). The other one is the use of copper as a backing plate, I've use this technique for many years now, and even the largest hole can be welded up. Once you get good at welding with MIG, you will be amazed at what you can acheive, believe me you will not be needing much in the way of filler !. Interestingly enough, steel from the 40's welds exceptionally well, much better than today's steels, far too many impurities these days.
Regards
Keith

[ozm29c]

Speedy,
Further to the constructive comments by other forum members. Here are some other thoughts to consider.
1. Always check what lies behind the proposed patch panel ie will it burn!!!!! Is there a fuel line or electrical wiring looms.
2. Prepare the joints to ensure that you are welding clean metal, Any contaminants in the weld pool will either weaken the join or blow out while you are welding like a mini volcano!
3. Keep the joint width between 0.5 to 1mm
4. Use 0.6/0.8mm dia wire with your smaller Mig welders. Having said that my thoughts on MIG welders are the bigger the better. Small MIG welders are fine but the bigger welders have more OOMPH!
5. If possible try to avoid using flux cored wire.
6. With patch panels don't try to weld in continuous seams, spot here then move away and place a spot there. Continue staggering your spotting until the join is filled-This takes more time but will help dissipate the heat and minimise your patch panel and parent metal from heat distortion. Remember HEAT is your enemy. A good cup of Tea or Coffee can be enjoyed many times
7. Use heavier gauge metal ie 1.2mm or at a pinch 1.6mm (than your parent metal)to make your patch from. This will help you to start your weld without blowing a hole in the joint. Looks no different on the outside.
8. Use sunscreen on exposed parts of your skin as MIG welders have a tendency to burn your skin with excellent results. Better still, try to cover all exposed parts of your body.
9. I know it is hard but try to weld with elbow length gauntlets (Leather gloves). I am sure experienced welders at some time in the past have grabbed a hot bit of metal with their bare hands by mistake. OUCH!
10. If you can borrow an auto darkening helmet, do so. Good for tak welding.
11. Buy yourself a cheap Chinese angle grinder but always use good quality cutting and grinding discs. Use the very thin section cutting discs and always use PPE (Eye protection and hearing defenders)
12. When grinding off the finished welds try not to use excessive force to speed up the removal of excess weld. All you will do is create heat with the end result being metal distortion. Once you have leveled the ground surface, get hold of a flapper disc to further smooth the surface.
13. Paint/prime the exposed metal as soon as possible to prevent corrosion.
14. The point of a screw driver is a very good tool for probing around the affected area to try and determine the extent of rust damage. Once you have cut the rust out of a particular area, then and only then is when you will know where to start your repairs.
Anyway I hope this will give you something to work with.
Don't rush the job
Good luck
Cheers
John Wilson
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[Speedy]

thank you everyone!
I felt confident enough to give it a shot today.
needed 18 guage first so I went to the local metal supermarkets and they were all closed on the weekends.
went home and found a small sheet in the garage, prepped it and set it up to be welded. got the welder out and found the sweet spot playing with the current and speed.
go to my part and it was out of wire!

so I will go and purchase the smallest wire my welder will take.
.024

[Speedy]

so here is attempt #2.
attempt #1 resulted in a epic fail. but I learned and todays attempt went much smoother.

woke up early stopped off at mr.metal. no small 18guage offcuts to give me so they handed me a large piece for free (enough to start patching the jeep after my practice)

with a nice flat sheet I took out the sawzall (wish I had something better) and cut out a test piece, got out the welder and found its sweet spot.

I know everyone is saying low wire speed and low voltage, but I went with what my welding book suggested (3-4 volts) as bench mark and worked from that.

here are some pictures.











shielding gas was used, compressor to cool down the welds with a blast of air, grinder with grinder wheel, 40 and 80 grit flappers to work it smooth.

I would always start my welds on the big piece of metal and move it to the smaller piece being attached. should I try just following the cut?