Learn to Weld?

[PrisonHack]

   First off let me apologize if this should be in off topic instead of the Car Guys section. I have been wanting to learn to weld, but know nothing about it. I have decent mechanical skills but know zip about body work. I would like to have the skill to install 1/4 panels or trunk pans. I checked out the local tech school but they don't have a night time welding class only a daytime program. Where would I need to begin? What sort of welder should I be looking at purchasing. I worked for ten years as an electronics tech soldering all day, not that soldering is welding but I am skilled in making solder flow and forming good joints with it. Not sure if any of that skill will be helpful or not.

[kab69440]

A small gas-fed MiG will do anything you need to do on a car's shell. Buy the machine and a cheap parts car and start cutting panels off it. Once you can run a nice stitch on a late model crap box, working with a Charger's metal will be gravy.

[Silver R/T]

I got my 140 MIG welder from ebay years ago. Then I went ahead and bought cart from Harbor Freight and gas tank from local welding supply.

[J.Bond]

Welding 101#

A little trick;

Buy a new mig welder, tell all your friends what you have bought. They in turn, will come to you to , help them, repair their stuff. By the time you have gooned all of your friends stuff.  You will have put a good amount of time under your belt welding , and should feel more confident welding. And the added perk is, none of your friends will hanging around wasting your time. Welding 101.......

[Ghoste]

Haha, so true. 

[Troy]

I learned to weld recently. It seems like every question about welding has been asked and answered so Google is your friend! Miller has a welding forum that has lots of great tips on getting started. Also, there are many "how to" videos on YouTube. For a car, most of the metal will be thin - which can be very different than a lot of the examples you'll see. I got some "hands on" help from 1hotdaytona and Dino so some of the tools and techniques came from them.

My tips:
* Use .024 wire (thinner diameter and less heat).
* Use Argon mix welding gas - and don't do like I did and use 25% CO2. Use 2-10%. Apparently more CO2 = hotter welds.
* Read the chart for your welder. Most of the settings should be right on! Make sure you have a thickness gauge handy so you know exactly what you're dealing with.
* Keep the nozzle and contact tips clean.
* Clean all surfaces to be welded thoroughly - dirty/rusty metal makes ugly/bad welds. I use 3M 2" surface prep and 50 or 36 grit grinding discs. Shiny metal is much friendlier.
* Make sure the joint is tight! Air gaps between pieces are a sure fire way to burn through and you'll be tempted to keep piling on the weld to fill it up - which generates even more heat. Don't be afraid to hammer/dolly as you go.
* Keep a pair of cutters handy. Snip the wire after every weld. A sharp point will start easy and smooth.
* Clamps. Buy waaaaaaaay more than you think you'll ever need! I also use self tapping screws about every 2-3" when necessary (like in the middle of a panel where a clamp won't reach. Filling those holes is easy after the panel is in place.
* Spend way more time fitting and trimming than welding. Otherwise you get to practice cutting and rewelding.
* Try welding from the top whenever possible. Molten metal is subject to gravity so don't put any part of yourself below it. Obligatory safety message here: wear steel toed boots, long pants, sleeves (not a sweatshirt or or long sleeved T unless you like them holey), and leather welding gloves. I also wear a welding cap with a backwards bill to protect the top of my head and neck. Hot metal will find whatever you don't cover! The arc light will also sunburn your skin. Get a QUALITY auto darkening helmet. Your eyes will thank you AND you'll actually be able to see what you're doing.
* Plug welds first! Sometimes referred to as "rosette". By far the easiest weld to master. I use a 3/8" drill in most cases. Plan ahead so you can actually reach your spots with the welder once the panel is in place! A trick I learned is to start in the center (on the back piece - usually thicker if it's a brace or rail) and "pull/push the puddle to the edges of the hole. I use more heat than typically called for, hold the nozzle at 90 degrees, and move relatively quickly. With my welder this makes an almost flat weld that I don't have to grind. Wish I had known that for the first required 500 or so welds that I did...
* Butt welding FYI - metal expands (and not always uniformly) so you're perfect gap doesn't stay that way. Be prepared to keep adjusting. Butt welding thin sheet metal requires lots of finesse and time. If I had to do it over, I'd have used more full panels and fewer patches just to avoid butt welds as much as possible. Butt welds can't be avoided completely so, when you do encounter one, it's best to tack, move to a cool spot, tack, move, and so on. Do not let the panel get hot - certainly not one specific spot. I have read to use compressed air to speed up the cooling process but also to let things cool naturally. Forced cooling can make the metal brittle.
* I use 3m 01991 discs to grind down the welds to a reasonable level then the 50grit disc above to finish them. Do NOT grind too deep! If welding from the top the weld itself will often "sink" below the surrounding metal so if you try to flatten it all completely you'll make the metal thinner than expected causing a weak joint. Be extra careful with butt welds as a fast grinder generates about as much heat as welding and will warp the panel.

Welds in order of forgiveness: most any brace to frame, formed (not flat) floor pans to frame rails, trunk braces to trunk pan, trunk pan to frame rails (only because it's a big piece of metal that car warp easily with the heat required by welding to rails), trunk extensions to trunk pan and quarters, dutchman panel (lots of overlapping joints), tail light panel to trunk gutters/quarters, trunk gutters to quarters. I did not have to replace any large exterior panels but I'd imagine that plug welding a quarter is easier than a roof (for instance) because it has more stiffening built in and most of the large areas are thick. A door/trunk/hood skin would seem fairly delicate as well. Basically, start at the bottom, then inside, then outside as your skills grow.

Troy

[Cooter]

Rule of thumb...
NEVER attempt to run a continuous bead when working on body panels. Always spot weld and a hole mess of em.

[green69rt]

I learned to weld by taking night courses at the local high school.   The practice, practice, practice.

[Davtona]

Very good advice and tips Troy. I must say I learned several things by reading your post. 

[Baldwinvette77]

i sold my xbox 360, bought a 200$ 180 made in china welder then melted shit together for a few months, watched tv, read a couple books watched a mess of youtube videos, then practiced more, some people have told me welding thick metal is easy, but personally 18 or 16 gauge is probably best to start out with, i think its the easiest at least,

idunno, all i did was practice a bunch 

[PrisonHack]

 Appreciate all the responses, it's a skill I have always wanted to learn

[Old Moparz]

Too bad the classes aren't at night for you, the one I took years ago were & it was great. The others are right, the more you do it, the better you get at it. One thing I was told by several people is to stay away from the flux core because it's messy, smells horrible & harder to get a better looking weld.

[Troy]

Don't even bother with flux core on sheet metal. That stuff is for fixing your rusty, broken tractor in the back 40 on a windy day.

Speaking of which, don't point a fan directly at you when you're welding. It blows the gas away from the weld pool and makes for crappy welds. The gas is to keep impurities out so you want it totally surrounding the area.

Troy

[green69rt]

Yeah, everything all these people say is good advice.   It really takes about 4 hours to learn the basics of welding (especially MIG) but it takes hours of practice to do it right.  After you get going you'll see how your welds start to looks better and better.  The weld bead will be more even and flat.  You'll learn to tell when a weld is going to be good by that "frying bacon" sound of the metal going down.  It's really kind of fun.

What's not fun is trying to weld without a helmet (don't even try it!!)  Also keep all your body parts out from under the place you are welding, including your feet.  First time you drop some hot weld metal on you shoe, it burns thru in about a second and you will be doing a funny dance in the garage trying to get your shoe off.  Just be safe.

[Mike DC]

I basically agree with the advice offered so far.


--  Flux-core wire = poop.  Get a gas shielding bottle from the beginning. 

--  You don't need to blow a lot of gas at the weld. Just do enough to push the existing air around the weld out of the way, which doesn't take very much pressure.  There's no additional benefit to using any more gas than that. 

--  Cut yourself a big pile of scrap pieces of steel to practice on.  Weld things together and then try breaking them apart (bench vice & sledge).  You're getting decent when the joined pieces are bending near the weld rather than the weld breaking.

--  The parts don't need to be really spotless for the MIG process to work but they must be clean enough to conduct electricity easily.  A bunch of rust or oil on the surface will screw up the process.

--  A little bit of air gap between the two pieces is a big challenge to fill. A big part of getting good MIG results is starting with pieces that are shaped & clamped/magneted together tightly. 

--  If your welder has the necessary voltage, it's easier to err on the side of thinner wire size and higher voltage.  Gives more control of the puddle IMO. 

--  But in the big picture, the wire speed & voltage knobs shouldn't be ending up radically far apart.  If you have one of those two knobs set WAY up, and the other one is WAY down, then you are probably doing something wrong.