Im rebuilding my 85 Z28 and i desperately needed a floor pan so i got a solid one torched off at the junkyard, now im on a rather tight budget and i saw that a 90 amp mig/flux welder was on sale, so my question is this, is 90 amps enough to weld a floor pan together and is a mig the correct welder that is needed, or do i need a tig(i can never remember which is which), ive never welded in my life but im willing to learn so if anyone can educate me a little it would be greatly appreciated

 

Mig will work, but check and see if it's really a MIG or flux core only. What's the difference? Mig you can hook up a bottle to use a shielding gas.

Technically you can weld your floor pans in with a flux core only welder, but the flux core is going to run a bit hot and you're going to have to deal with slag. It's not ideal for body work, but on a floor pan where you're not going to readily see it, would probably be one of the better places to use one.

Here's one of the better sites out there regarding welding tips and such: http://www.weldingtipsandtricks.com/index.html

It's very hard to learn how to weld without someone next to you to show/explain what you're doing wrong, but it can be done.

Your best bet is to get some material the same thickness as your floor pans and practice and do some destructive testing in a vice.

A floor pan is a good place to practice because like I said you're not going to see it, plus it's almost entirely flat welding if done properly, so no out of position stuff (overhead, vertical, etc).

Practice first, make sure all your pieces fit together nice. Clamp them or tack as you go and make sure the fit is perfect, and you should have no problem doing this yourself.

If at all possible, post a link or specs to the welder you intend to buy and I'll give you my opinion.

Most people recommend you stay away from the flux core only machines because like I said, they're not optimal for body work and sooner or later you're going to want a bigger machine. But having said that, I did my first body work with a flux core welder, welding the holes closed on my '92 Camaro when I swapped spoilers and it came out just fine. Skim coat of bondo and good to go.

That was about 7 years ago or more that I started on that project and now I'm welding and fabricating metal for a living.

OH! BTW... These are unibody cars, so don't cut the entire floor out of the car at once unless you brace it first. If you cut out sections at a time you should be ok. I don't know how bad your floor pans are or how much you intend to replace.

Mathius

 

90 amps is too much.

Low setting, wire speed set to around 3. I do little figure 8's and draw a continuous weld. It warps the crap out of the panel, but I don't care about it hiding under the carpet. Saves time.

When grafting quarter panels, you will blow holes until you get used to welding.

My advice. Use a .030" flux wire, low voltage, wire speed around 3. Tack, move, tack move. go back and forth around. don't stay in one spot too long. You start blowing holes and it will look like swiss cheese.

-- Joe

 

I'm using my 80 amp 110 flux welder on the camaro right now. Like any GM or Ford, it needs quarter and fender work. Seems like everything I buy

Anyway, if you've got it mastered I actually like the flux. Made some frame repairs, and got one quarter grafted in this past weekend. Hopefully within two weeks I'll be ready for paint.

-- Joe

 

He's saying it's a 90 amp max machine, I believe, which will work out just fine. It's the flux core only I'm concerned about. It's ironic because these machines are often cheaper so people end up starting out with them, but the reality of it is, flux core is harder for the beginner, particularly if you're welding something structurally. Slag deposits are something a beginner needs to learn about, but most of the guys buying these 90 amp machines are just doing body panels, so they neglect to learn proper weld techniques for structural welding.

There's nothing "wrong" with flux core, it's just not ideal like I said. It runs hotter, so you have to watch for burn through a lot more. It also leaves slag deposits because it lacks a shielding gas. Also in my own personal experience, flux core wire just plain goes bad easily. I remember when I started welding back in the day, the vocational school I learned at used to double shield (run a shielding gas and flux core wire) because the wire would go bad quickly and they'd have nothing but porosity.

I've been running flux core at work in the field almost constantly over the last year except when I had to run some stainless. I'm not a fan. The best I can say is it does the job. My shop sent out a 110v MIG, even though I'd rather they just send out a 220v stick welder and I've welded anything from 16ga to 3/16" material with it over the last year. Technically we welded some hangers to a 24" thick I-beam, but the welds weren't weight bearing and I don't believe for a second they are strong, but I do what the boss wants.

The wire mfr's have gotten better over the years and the wire doesn't go bad nearly as quick as it used to, but it can still go bad. Additionally due to the amount of slag and sparks a flux core puts out, your liner can get dirty fairly quickly with extended use and you can get porosity from that. You can remove your liner and soak it with paint thinner to clean it out. Just make sure the thinner dries out before welding again.

Mathius

 

I think we're saying the same thing, but the problem with a 90 amp cheap machine is normally you only get two settings 'high' and 'low', low being probably 45 amps which is still too high for a 20-22 gauge body panel.

Nicer machines will have 4 or more heat settings.

Flux is harder to learn. I started with mig, then flux in the early 90s. Own both, flux gets used more. Especially outside when the wind is blowing.


-- Joe

 

this is the one i looked at i think
http://www.harborfreight.com/welding...der-98871.html
but as far as the whole flux/mig thing goes, youre saying its easier and possibly better that i start out with a mig

 

that welder is a flux core welder.

flux core wire has its uses, and is very good for what its needed to do, but for work like this, it really should be done with a gas mig. The cost a little more, but the finished product will look a lot better.

 

im not too worried about appearance, its a floor pan that will be heavily undercoated, because this will be my daily driver, as for anything else i may weld i think grinding and sanding will take care of any slag, and out of curiosity what are places that have migs for decent lower prices, i dont think i really need anything high powered just enough to get the job done

 

That's a good point I hadn't thought of. And the machine he posted suffers from exactly that limitation.... My first flux core machine had more settings than that, IIRC.

Ok... you can get by with flux core and do an ok job on your floors, maybe even a good job, but down the road you're going to want something better and the learning curve is harder with flux core.

That machine you posted will technically get the job done, but as anesthes brought up, it only has a low and a high setting for heat. If your floor pans fall somewhere in between, that machine might end up being worthless for you unless you intend to tack weld your floor pans the entire way around.

Listen... I'm all for saving money, but I don't recommend that machine. Why don't you post pics of what you intend first. That would help decide on what welder you want to buy. How bad are you floor pans?

Mathius

 

lets put the shape of my floor pans into this perspective until i can post pics, im 6'3 245 lbs with a 36in waist and i can step onto the ground from the inside of the passenger side, the only good part is the trans tunnel which has no rust at all

 

Keep looking...
That thing is a turd... even for what little you want to do.

 

first tim eposting pics i made a photobucket acount and dont know how to use it so bear with me but heres the url to my album, http://s910.photobucket.com/albums/ac310/tylercamaro/, the pics of the rusty floor pan are in there

 

I picked up a 90 amp wire-feed welder from Princess Auto for $180. It has four power settings, infinite speed control, and can do flux-core and gas welding. You should be able to find something similar for a lot less in the States.

 

Those spots are bad, but I would still not replace the hole floor. It looks like you still have a lot of solid metal in there, just a few really bad spots. This one looks to be the worst: http://i910.photobucket.com/albums/a...o/100_2012.jpg



The reason for that, is your seat support is in that spot. Since you're a beginner, I'd recommend just replacing the hole thing from a junk yard. Drill out the spot welds and pull it loose. You can do the patches on your floor, but creating a compound curve like that to repair the seat support is probably beyond your abilities. I know it would stretch my limits.

Welding in sheet metal for your floor is fairly easy stuff compared to the seat support.

Cut out your rust out with a saw zaw, jigsaw, plasma cutter, 3" air die grinder with a cutting wheel, or an angle grinder, whatever you have. Snips would do a nice job too.

If you have rust through in an area where you have overlapping metal, try to replace each layer separately. (why I recommended replacing the seat support)

Make a pattern out of poster board. Lots of guys will skip this step, but then you can end up with poor gaps or multiple patches. It's easy to tape an extra piece of paper back on until you get the cuts just right. Then you can easily transfer to sheet metal. Thin cardboard works good for this step as well.

Once you have your patch ready, spray any areas where you're going to lap weld with weld through primer. Weld both sides of the lap if you lap joint because you don't want water getting in there. Seam seal when you're done for extra protection. Tack your stuff in place first until you're satisfied with everything and then stitch weld, jumping around to spread the heat out. Give it time to cool in between welds if you need to, to prevent major warping. Warpage in a floor pan isn't a huge deal, but it's good practice for when you want to do a body panel later.

Attack those areas that aren't rusted through, but show rust with a wire wheel and get them coated with something. Primer and paint(etching primer would probably work good for rusty areas), truck bed liner, anything that's gonna protect the bare metal.

I have heard the harbor freight TIG welders are pretty durable from guys that are IN the sheet metal trade and abused the hell out of them, but I was in harbor freight the other day and noticed the entry model no longer comes with a TIG torch, you have to purchase it separately, which means more money. All of the MIG's they carried had the 1/2 switch for heat, which isn't what you want.

In the long run you're much better buying a nice $500 110v lincoln (or miller if you can find one) or maybe finding a $500 machine used somewhere for less. Either that or wait 'til you can afford a 220v machine. Thermadyne makes some nice 110v equipment, including stick and tig welders.

Here are two used dealers, but I know nothing about either of them.
http://dir.yahoo.com/Business_and_Ec...quipment/Used/

Probably better to check craigslist in your area. I've even seen welders in the free section, but you have to jump on them in the rare occasion they pop up.

Something like this Hobart is nice because for $100 you can convert it to MIG later: http://store.weldingdepot.com/cgi/we...ot/500487.html

Mathius

 

well today i started repairng that hole, i bought a junkyard floor pan from an 87 t/a that was really solid( although i feel like a sinner that destroyed a good third gen) and yes i doing it in patches not cutting out a half and putting it in, there is solid metal still left i have to cut the bad and find the good

 

be careful with the harbor freight flux core welders I bought one years ago holds up like a champ but the feed tends to jump around and can make it hard to hold an arc, + like others have said it tends to burn through on thin metal very easy even on low settings. Good luck alittle pratice and youll be welding like a pro in no time MIG is the easyest to learn.