body work for a newbie

[Speedy]

can anyone lend a newbie that is familiar with a MIG welder some advice on welding flush patches on his vehicle.

I have a MIG with shielding gas.

im not sure what I need to cut sections out and other tools.

I have been slacking for 2 months on my project and I think its time I started at least doing body work on the spots I can while the tub is still on the frame.

[Scott Bentley]

Originally Posted by Speedy

can anyone lend a newbie that is familiar with a MIG welder some advice on welding flush patches on his vehicle.

Patience is key here.... Had I started off with more patience working on my M151A2, I would have saved myself a ton of time in the end. If your gut tells you its going to look like shit, it probably will.

Most important tip I can give you when working with MIG on sheetmetal is that everything must be clean and free of rust, grease, and paint, otherwise you will never get anything decent. This is crucial with MIG.

Secondly, if your starting out, all of your butt welds should really be a series of quick tacks until its complete. Heat is your enemy with sheet metal body panels. It is very easy to warp things if you get carried away, and it takes surprisingly little heat to do allot of warping.

Try and use the smallest wire available. IIRC, I used .22 wire. Same with the voltage, lowest possible, with a nice slow feed speed. Turn your Argon/CO2 up to no less than 20 psi, not only will it keep your weld clean, it will also help keep things cool. Practice on some sheetmetal first before you attempt anything on your project.

Take extra time to make sure your patch panels fit well prior to tacking them on. No more than 1/16" less gap between patch and the body for your butt weld, but you will need some gap. Use welding magnets to hold them in place as this will keep everything level/flush.

Lastly, and this is my own personal tip. If you want it to be flush, try to keep your gun perpendicular to the weld when your doing your tacks rather than the angle most use when wire feed welding, this will keep the heat evenly distributed between both the existing body and the patch.

Lots of good tips can be found all over Google.

Thats about all I can give you now.

Scotty

[cantankrs]

Hi Michael,

Anybody wants to learn about forming and welding coachwork I recommend Ron Fournier's series of sheetmetal handbooks.

I highly recommend the Metalshapers Association website. Heaps of pictures and advice to learn from.

I bought a MIG and then had to learn how to use it which for some reason was hard for me and after that knowledge, it improved my oxy and stick welding - go figure.

You can't weld rust despite what some jokers will tell you. Some steel rusts such that the whole thickness is a hard rust that looks like its solid - it kinda is and it's hard to sand and grind but it's brittle and touch the mig to it and it just melts and falls out. All that has to be replaced if you encounter it.

You need good replacement steel same thickness as the old. I've used zinc anneal sheet with success. I'd be interested to know what anyone else thinks about that.

I use 0.6mm MIG wire on body panels.

Don't hold a bit of 16 gauge on the edge of a lump of channel and tip the edge with a hammer - clamp it down or use some sort of weighted bag (sand bag or lead shot filled leather bag) and rest your hand on the bag to support it - my wrists didn't take to the shocks from holding it down.

The most important tools are the eye, ear, face, nose and throat protection. You only get one pair of eyes, you want to protect your good looks (face), and you want to be able to breathe without rasping when you're old.

The most often used tool tools for me are a 4" angle grinder (can get 1mm cutting discs here now), a Black and Decker PowerFile. One hammer - I'd pick one with a round, slightly convex face and maybe with a pick on the other end but not needed. You want some clamps - G clamps, vice grips, whatever you can scrounge. You want something solid to clamp things to that has a straight edge and can handle being hammered - a bit of I-beam might do the trick and the grinder with grinding disk can dress it up how you want.
A magic marker and a pencil and a ruler and some scissors and cardboard to make templates and mark out. Also some snips are handy - I prefer Wiss left and right cut pair of aviation tin snips.

Try and make your patches an exact replacement shape.

The powerfile is quick and easy to clean the edges around the hole you intend to patch. Can't mig weld paint, grease, or sealant. (use scraper and or degreaser on grease).

You aim to shape and fit your replacement steel patches with no more than about a 1mm gap all around. You turn the mig up a bit and tack the piece FLUSH all around and with a minimum number of spot tacks i.e. 4. Stop and check the position and flushness with the surrounding metal. Cut the spots and make corrections until its perfect. Then tack half way between using same small hot tacks. Don't let the metal get too hot. Once you have nice low build tacks with 100% penetration every one inch, then I tend to do 1cm (just under half inch) welds at opposite areas and keep the panel cool. I use a wet rag from a bucket to cool the panel if I think it needs it.

I'll think about what I've forgotten to mention

Regards

Alex

[Richard Coutts-Smith]

Another top tip is using a Copper backing plate. Piece of old electrical Buss Bar is perfect. Clamp behind and across the patch to be welded. As the weld will not stick to this Copper plate, it makes filling the join a lot easier, as well as sucking a lot of the heat out of the job.
Most Scrappies have drums of this stuff, and at pay per weight it is worth every penny.
As mentioned above, the extra thin cutting discs are a must, they are magnificent. The better fit a patch, the less welding, less heat, less clean up. Speaking of clean up, standard grinding discs tend to leave a pretty nasty finish. I use a softer compound polishing disc (they're white and I can't rember the brand, usually used for stainless steel work) after removing the worst of the weld.
Take your time, amazing what a mess that extra 1/2 second of welding can do.
Good Luck.
Rich.

[Speedy]

Originally Posted by Richard Coutts-Smith

Another top tip is using a Copper backing plate. Piece of old electrical Buss Bar is perfect. Clamp behind and across the patch to be welded. As the weld will not stick to this Copper plate, it makes filling the join a lot easier, as well as sucking a lot of the heat out of the job.
Most Scrappies have drums of this stuff, and at pay per weight it is worth every penny.
As mentioned above, the extra thin cutting discs are a must, they are magnificent. The better fit a patch, the less welding, less heat, less clean up. Speaking of clean up, standard grinding discs tend to leave a pretty nasty finish. I use a softer compound polishing disc (they're white and I can't rember the brand, usually used for stainless steel work) after removing the worst of the weld.
Take your time, amazing what a mess that extra 1/2 second of welding can do.
Good Luck.
Rich.

oo I like that tip! would the copper mostly help so you dont blow thru?

one of my neighbors told me about putting clay or something around the weld area to pull in heat also, not sure if I understood it right.

[Richard Coutts-Smith]

Very difficult to blow through with a copper back plate, but too keen an effort will still make a mess....
Rich

[Ken Hughes]

Hi speedy, some good advice here so far,practice on some old unwanted metal of the same thickness for a start(so yo do not bugger up the good stuff first)till you get the hang of it.
Also be care- full not to grind too much out of the weld when cleaning up the weld as it will crack and you have to do it all again.
Check out metalmeet dot com as well.
Do not hesitate to ask questions as there are a lot of talented people on this site .

[Speedy]

WOW!
thank you lots Scotty and Alex!
I feel much more confident about my first try.

going to keep your responses handy as I will be referring back to them some more and the links provided.

Alex. I dont understand this part "Don't hold a bit of 16 gauge on the edge of a lump of channel and tip the edge with a hammer - clamp it down or use some sort of weighted bag (sand bag or lead shot filled leather bag) and rest your hand on the bag to support it - my wrists didn't take to the shocks from holding it down."

also, willys used 18guage steel?
and should I expect to be using any body filler?

seems I need to pay a visit to my uncle for some tools (vice grips for body work)

thanks again

[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