Ok, i've realized i can not weld, either that, or the welder i bought isn't doing the job, i need help from any welders out there, i'm in a storage unit doing this, the only outlet is a 110, so thats limiting me to a wire feed flux, most migs are 220, i'm working with a roof "skin" that i've cut, but it seems the welder is too hot for this thin metal, i'll confess, its a low buck Chicago wire feed from Harbor Freight, am i trying to do the impossible, or will this welder work, it has high/low & on/off switch, & a knob for the feed, any an all help would be appreciated. The pix will give an idea what i'm up against. Am i going to need a Mig to do this job, i already have the skin from a donor roof cut & mocked up, seems like all this cutting went super smooth, but the welding is turning out to be a PITA.

I think you will want to get a better machine. you need to be able to run less current, and the gas will make a ton of difference. You'll never go back. Flux core is for convenience, like repairing in the field.

I believe I would be on the lookout for someone who can weld and let him take it from here. The money spent on a person who has all the tools and experience would be money well spent. How much better would you feel if you could drop your car off and 2 days later pick it up with new top in place?

Agree with both of the above. Either have someone else do it (if you can afford) or find better equipment.

Thin material is difficult to weld, burns through and warps unless you have equipment with very precise current control and experience helps too.

Ideally, you would TIG weld it, but a good MIG welder and some practice could work for you.

I was at the local Rental Equipment yard last weekend renting a Van Truck w/ lift-gate. In the office, I noticed they had portable MIG welders available for rent.

Of course, I own my own welding equipment, MIG among it, but if I had needed it, I could have rented.

Flux core works great for some applications, but sheet metal is not one of them.

If your serious about doing this yourself then get a MIG. Also, you need to clean the rust off the areas you will be welding to. Rust and dirt will contaminate your welds.
Buy some .023" diameter wire and take some scrap metal the same thickness as your roof and begin practicing with it.
I had to learn to weld while doing my car and it took me a couple of days practicing with scrap to get the settings right.
My welder has a Spot Weld setting that controls the length of time the welder responds to the trigger pull.
I used this setting and played with the heat and wire feed until I got a nice spot weld with no blow through.
With thin metal you want to spot weld to prevent overheating and warping the panel. Keep a wet rag (quench cloth) nearby so you can keep things cool. Start by spot welding every 3" or so along your seam all the way around. Use a small flat blade screwdriver to keep the edges of your metal lined up as you work your way around. Once you complete the first set of spot welds you repeat the process placing a spot weld in the middle of the previous welds. Keep this process up until you have a solid line of weld.
Roofs are one of the harder panels to do without warping but you can do it if you practice on scrap before you tackle the real stuff. If you cannot produce the weld on the scrap material you won't be happy with your repair work.
IMHO Harbor Freight sell cheap, poor quality stuff. Check craigslist and you may find a used MIG for a reasonable price.

Look into adapting your welder over to gas. I had a Century 110 that I converted over to gas and loved it.

I had to weld up a heavy steel post in the middle of nowhere. I have a good 110v Mig and I borrowed a friends gas powered generator. Worked like a charm.

That may work for you to get more power to the welder since most circuits in those sheds are 15amp and you need at least 20 amp to run a good 110 welder.

As for the welder I have heard more than one person on here buy the Harbor Freight welders just to find out they barely or didn't work at all.

Also another vote for GAS mix on your welder.

Heres a trick u might try, use a small diameter extention cord, I have a Craftsman 110 v welder useing flux core wire works like a charm on old chrysler sheet metal

Thanks for the tips, i'm very happy with this welder for what i paid, got it on sale for 79.95 (normally 149.95), then a customer gave me a 20% off coupon at the checkout, Harbor Freight honored it with the sale price (shocking), so it came to 63.xx, i got a 1 yr. warr. & the total was 80.xx, so i felt i did good, now when i brought it home, i tested it on the donor back panal, welded a soft washer on, it flowed like butter , i'm like damn, not bad, but now that i'm doing the skin, its getting stupid, so i can't blame the welder, i'm sure it'll work great with thicker metals, my extention cord is about a 60"fter, i may just have to find someone who will do it for a reasonable price, if not, i'll have to think of something, because i really need a 220 outlet for most migs, now HF has a true mig that runs off 110, its 189.00, but its "special order", & i'll most likely not see it till spring if i ordered it now, i'll try a thicker wire 1st, see how that does, this wire is pretty thin.

turn the heat to low turn wire speed to very little, 1/8-1/4 stick out line it up with metal and pull trigger and let go quick after a bunch of this you will get the hang of how long you can hold the trigger down before you blow through. Remember you cant weld sheet metal you have to do 1000s of tacks/spot welds or you will warp/burn through. and remember to not keep tacking in one place move around to other sides so you keep the heat down on the panels.

I buy all kinds of tools from Harbor Freight Tools, most of which I have been very pleased with, but as for their wire-feed and low end MIG welders, I wouldn't.

The quality isn't what it should be and repair/replacement parts are just not available. The poor quality of the units makes achieving good results near impossible.

I would suggest you do some close comparison between the HFT units, and Lincoln, Miller, or Hobart welders of similar rated capability. With welders, you do get what you pay for in quality, parts and operation.

If you can find someone that has a Name-Brand unit, ask if you can try it out; See for yourself how much easier it is to use and achieve better results.

Harbor Freight, in addition to their Chinese import brands, also sells Hobart Welders. That might be a consideration.

Another possibility, Professional Welding Supply Shops have their best annual discount "Sales" in December, the very lowest prices of the year, that is if you can wait a couple months.

I have to agree with the comments above. You need gas and .023 wire. I am a welder and can not, for the most part, achive satifactory results from one of those cheap flux core jobs (my satifaction anyway). I can't imagine how difficult it must be for someone to try and learn to weld with one of these. There is a night and day differentce between a good welding machine and a cheap welder.

The main problem is the flux core wire! The wire with the flux in it is too thick for the thin sheet metal. If your really careful you can weld with it, but it will want to burn through the steel alot. Use the gas shield and the thinner wire and you will love it. The welds will be much cleaner, and the thinner wire will reduce the chances of burn through.

Good idea's above. I would look to hire the rest....that's not a first timers job there with multiple angle pieces around the window and not having the right equipment. Front glass and gasket needs to come out as well

BUT please remove the interior before you catch the car and yourself on fire!!!!!!

110 migs are not hard to find. i have one and they are the best for doing auto sheetmetal jobs. try one, its night and day with gas vs fluxcore.

The S-10 (0.024") wire and C25 (75% Argon, 25% co2) gas.
Someday I will get a real welding cart, but this works for now....