This will probably be a little lengthy, so bear with me. So I started getting my feet wet with welding 20 guage sheet metal. I"ve been smoothing my firewall (60 holes) and a couple of small patch panels. I've been doing spot welds, making sure that nothing gets too hot. After welding all visible gaps, I ground down the spot welds. After doing some touch ups and grinding some more, I thought I was all done. I decided to put a light behind the patch panel to check my work, and I see A LOT of pin size holes along the seam that are not visible without the back lighting. So am I doing anything wrong? Should I go back and spot weld the pin size holes. Should I have welded a 1/4" at a time for a continuous weld? Should I just skim coat it with filler to fill the tiny holes and call it good? I look at some of the TIG welding out there and I'm wondering if that would be a better process. Lower heat and a continuous weld. Plus MIG welds are so damn hard. How hard is it to become a decent TIG welder? Can a novice working on weekends figure it out? Any opinions would be appreciated.
Yes go back and weld up the pinholes. DO NOT fill them with filler. Spot welding is the best way to do sheet metal with mig but it is time consuming as you are probably finding out. I am a weekend guy and I have learned to TIG on my own and it makes finishing sheetmetal much easier. Now I am no Brian Bass but I also use my welder about 2-3 time a month not everyday like a professional so I don't expect to be up to that standard.
Plus 1 on filling the pin holes. I am also a weekend TIG welder. I prefer it over my mig. It is much easier to see what you are doing (for me anyway.) Nice soft welds are also a plus. Everything has to be really clean ,which is a little time consuming, but well worth it in my opinion.
TIG welding steel is not difficult. Thin steel may be a little more challenging- I've never tried it. TIG welding is similar in method to oxy-acetylene welding. Here's a TIG weld I did today on a bit thicker than sheetmetal (3/4" plate to 3/8" wall angle iron). Disclaimer: It's not a structural piece.
i'm guessing your not overlapping your spots enough, if you have no gape and your spots overlap by 25% then there should be no holes.
Man, I TIG'ed for the first time tonight and it was alot harder than I thought.... but I'll just keep practicing and practicing!
oh and it was nearly impossible for me to see anything I was doing, due to the fact that I'm taking a welding course at my local community college and they don't have the best welding masks, so make sure you have a decent one!
Hahahaaa, if that's just a BIT thicker than sheetmetal, then I must be ALMOST as good a welder as Jesse James!! Just busting your balls.
If your TIG has a downslope function, use it. This slows the cooling process of the weld pool, and prevents pinholes and cracks. Also try using copper-coated TIG filler rods as the copper can help a bit. Rusty or oxidised metal will be your worst enemy with a TIG. Good luck
I'm gonna toss out a third option. Buy a small torch and gas weld your sheetmetal. It sounds intimidating at first, but it really is a lot easier than it looks. Once you have gas welding well in hand, TIG will be a short jaunt skill wise. It's easier to get used to all the new coordinated movements when it's just your hands (as in gas welding). Then, later on when you jump to the TIG, the only change is rocking the foot pedal for heat instead of moving the torch in/out. Torch welding is also a lot less sensitive to cruddy material. It takes time to become good at it (as with all welding), but once you've got it down, you'll be glad you did.
Another help may be using a flat, solid copper piece of sheet behind the spot when you weld. it will give the filler support and an area to expand, filling those little holes. Mig and tig do not stick to copper.
Harbor freight has a good cheap mask that will get you through till you can buy a good one.... Saved my eyes my school had cheap masks to..
I worry when I see the words 'good' and 'cheap' used in the same sentence when talking of welding masks. You only get two eyes in your lifetime. My advise is to save your money if you have to and buy the best mask you can get. That mask if looked after and maintained should last you many years, also get one with a TIG function. Don't think that just because you're a weekend welder a cheap mask will be OK, welding flash is cumulative over your working life. The more you are exposed in your younger years the less you can tolerate as you age.
Very common problem with MIG welds. Even for people with experience. Many times, MIG welds will just lay on top of the metal, instead of penetrating it..and the tack weld next to it. You need more practice, and maybe a little instruction on setting up your welder (speed/heat). You'll get better with time and experience. I do tacks, until they are very close together, between 1/4 and 1/2 in. then do 1/4 in stitches to fill in between. I still need to go back and reweld some spots after grinding, though even after doing this for 25+ years! TIG is much better for quality welds on thin metal, as most others have said. Gas can work well, too, as long as you get enough practice with your hammer and dolly work. But BOTH are more time consuming, and take more skill and practice to get right.
Beware of the masks that use an orange tinted lens (auto or shaded). There is a little red "eye" in the TIG puddle that is your best indication of how well you are controlling the heat. It is usually invisible with any sort of red tinited lens. TIG welding is a LOT easier when you have good visibility through the lens. If you go lighter than a 10 shade though, you may have problems with cumulative flashburn.
In my opinion tig and mig both serve a purpose. I like to use my tig for fine detail work, some place that the weld will be visiable. Where as the mig is great for just sticking things together fast (glue gun). Dont get me wrong you can lay down a killer bead with both machines. Like mentioned before its all about practice. If you do end up getting a tig machine sit down with it and just run beads, practice making corners, changing direction, ect... If you get really daring try welding two soda cans together!! Its not as hard as you may think. Mike
after years of not quite tigging like I used to, I went to the dollar store. 5 bucks and a set of reading glasses for under my helmet and it all became clear to me
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