gas welding advice

like most, i've been using mig for all my sheet metal repairs...i'm happy with the results i get, but i'm over all the grinding and hard welds...if there is a better way i'm always willing to try... i know that gas is a more workable alternative and i'm ready to give it a go... i've already got 0 and 00 tips and am wondering if there is a preferred rod for sheet (18g)? i've heard of possibly using mig wire, but i don't know if thats a good idea... should i use the 00 tip? also, can i run a continuous bead, or is it better to do 1" or 2 " at a time? i'm not the greatest gas welder (i can stick most anything together- but its not always pretty!) so any other advice is more than welcome

 

heat it till it melts together. I'd stay with the mig and grinder. more heat less fire...?

 

When I have to gas weld something I usually use my Dillon mark 5 pistol grip torch and use .35 wire from my MIG. I have it spooled with the ESAB easy grind wire.

Scott...

 

my dad taught me 45yrs ago using coat hanger wire,isn't migwire harder and brittle

 

i use a 00 tip, and proper filler rod, i usely cut the filler rod in half just to make it a little easyer, do a little let it cool, do a little let it cool, then i grind it a little and hammer it to stretch it back out, i think really i should be hammering it when its still hot but it seems to work out fine. hammer with a dolly behind it.

 

this is the least helpful thing any one has told me in some time... thanks

 

i thought the heat from the mig process made it brittle, not the wire itself

 

thanks... what rod for 18g steel?

 

Disclaimer: Check the threads, there are some really talented people here and I'm NOT one of them. That said, the best here weren't born with a torch either. They got instruction and training then they put their hand to it. Using a mig welder is easier but not better. The welds are as hard as a whore's heart. As you may have discovered you need to work the welded area after welding to correct any shrinkage the heat has caused. Tacking the area helps to position your material and transfer heat resulting in less dolly work later. Buy some rod 3/32" at the welding store and see what you like to use. Check the work to see if you are getting good penetration. Work slowly and check your work often, any adjustments will save lots of time later. The finished welds should require lots less grinding, they are easier to finish and can be worked with a dolly. Tip selection- cut some tabs of 18-20 gage metal and try to weld them without a filler rod. You can adjust the torch and practice-practice-practice. Clean your work area of combustibles, wear proper eye protection and gloves. Tech tip- If you blow yourself up or burn the garage you'll never get good at this- Watch someone that is good- at least better than you and watch learn and listen- Lastly never listen to me I'm an idiot
Good luck-

 

3/32" is what i'm using.

 

was more of a bump, you were down the list. good luck

 

If you want to metal finish the panel you installed. You will never do it with a mig. You need to use a double 0 tip for 18 gague and a tripple 0 tip for 20 gague . Your panel you are installing has to fit perfect. No gaps, as well as the profile and shape of the panel. In other words its got to really fit. Tack the panel in place a little at a time. You will have to hammer the tacks as you go along and back them with a dolly. If you hammer the panel to much you will strech the panel. This is the part that takes pratice. Once you have the panel tacked in place you can start to hammer weld the panel in. Weld only a half of a inch at a time. You need to hammer the weld when the weld is hot. You just want to hammer enough , while backing it with a dolly to keep the panel from srinking. If the panel moved while you were welding you need to stop and get the panel back to shape before welding again. You will have to move around on the panel. Use your hand as a guide. Work the lows and the highs as you go.You will need a stand to put your torch in because you will be picking it up and down alot to work the welds and control the panel with the hammer and dolly . I use 1/16th gas filler rod. If your panel is fitting perfect you can almost fuse the panel in with very little filler. A wet rag can to used to cool the panel so you can get your hand on it to check the lows and highs as you go.

 

very helpful ... thanks.

 

Real good description of "fusion welding" on panels... low pressure on your acetelyne, add in a little oxygen as required and Flathead34 is right on the money.. little or no filler rod required... "tack" the panels every inch, hammer and dolly and work your way back at each weld slowly, filling in between with more "tacks"... watch the metal, and as soon as you see it start to "flow" remove the heat... this technique requires practice and patience, but ends up wit great result

 

i have patience and don't mind practice... i plan on doing this kind of stuff for a long time, so i want to know the best way and do my best at it... 27tudor, you answered my last query without me even asking it... funny, since i will be welding patch panels on my 58 apache and finishing the chop on my- wait for it, yep- '27 tudor... thanks

 

Some good advice here. Perhaps someone can post a chart of the psi settings for the different size tips. My chart is buried in a book somewhere up in the attic. I've cheapened myself with MIG over the last few years, but seeing video on the Henrob 2000 has garnered interest in going back to the old ways. And I got a free bucket of old tips hiding in the corner of the garage.

 

My thoughts:

use 70S2, 70S3 or 70S6 TIG rod, somewhere between .030 and .045. You can use MIG wire to gas weld -- it's 70S6.

The #1 pointer is to make the panels fit as perfectly as possible - no gaps, edges touching, surfaces smooth across the seam. Tack, hammer/dolly to smooth. If the seam is "right" before you weld it, and tacked every inch or so, then everything that follows is 10 times easier. This applies for any sheetmetal joint regardless of the welding method.

Fine control of the heat by the angle of the tip to the work, and the distance from the panel. Make a puddle and dip the rod into the puddle -- this actually cools the weld puddle slightly and gives you more control.

Welding will distort the metal. The cause of the distortion is shrinkage in the heat affected zone. The solution is to hammer the weld on-dolly (listen for the "ding-ding" sound when you hammer). If you have a big lumpy weld grind the top of the weld off before you hammer it -- only grind the weld bead!

You can hammer the weld while it's hot, and it's easier to hammer but it is pretty nearly impossible to judge how much to hammer it at this stage and it's possible to over-stretch it and have a more complex job of finishing the seam after it's cooled.

 

i agree... i almost titled this thread "going back so i can go forward"... my mig panels are good enough for everyone i know- except me.. i can do better... but its as much the process as the final result...grinding mig nubs is starting to drive me crazy- adding all this metal just so i can grind it off... i would like to pick up a henrob or dillon(?) at some point, but theres no reason i can't get going with what i have... the psi settings seem to be good starting points, but i always find myself doing a little adjusting

 

While I have to agree that a tight fit/less rod is good in alot of applications,
its not all the applications.

With gas welding, and even tig welding,
when there is a flat panel (like 28/29 pickup),
sometimes a gap is good.
Even tacking 2 ends and using a cutting wheel sometimes (.040) to make an even gap,
then use thicker 3/32 as it doesn't boil as fast as the thinner -
with an 000 tip.

What it does is when the filler metal cools,
it contracts the panel so it actually cools straight,
instead of converging like tectonic plates make a mountain.
It is hard to hammer flat panels flat.


The best thing about gas welding is you learn tricks that you can never learn by going straight to TIG.

Mig welding sheetmetal is for hacks, even if a finished car looks cool.
Look at the inside of a migged sheetmetal car, it usually looks like shit.

An interesting thing to do is gas/tig weld over a migged section of sheetmetal that's been "grinded" smooth.
There will be tons of cracks where the different metals aren't actually attached,
they are obvious when they are red, hard to see when its silver.


TP

 

thanks zibo... i agree on the mig thing- though i've always given attention to both sides of the panel whenever possible... i've also experimented w/ welding from the back so less grinding on the visible side of the panel was required- all bullshit when it comes down to it, so on to gas.. after some practice my first real work w/ gas will be "touch-ups" on a couple patches i did that still have pin holes and cracks like you describe...

 

Good thread. I use a henrob with 1.5 tip. I like a slight gap. 1/16" works for me. 1/16 rod. Without a gap it feels like the metal pushes to hard. I hammer while the weld is hot and cool with air. After cooling I make sure everything is where I want it before the next weld. If I over stretch, I just heat and cool to shrink it a little. I weld 1/2" or so at a time, depending on how the metal is moving. I don't know if I'm doing it "right" but the more I hammer weld the better I'm getting, and the less I'm afraid of the heat the better it works for me. If I end up making a long weld and it starts to cool, I'll sometimes go over it and heat it back up, then hammer. I've had good results with a shrinking file for final smoothing after its cool.

 

Tip number one when gas welding... bend a right angle on one end of the rod so you know which end you have been heating so you don't grab the hot end... ask me how I learned about this trick the hard way

For vehicle sheet metal tack in several places to hold the part in place then stitch weld in short sections allowing for cooling between sessions of welding.

Some people prefer to start at one end and then jump to the other end while the first one cools but I have found it better to stay with one end and work toward the loose end if you have the time.

SOMETIMES if you move from one end to the other you MAY find some problems with two types of warping when you get to the meeting point of the sections of weld.

You can buy from bodyshop supply vendors "Heat blocker" cream in large tubes like toothpaste run a bead down the sides of the seam you are welding on maybe an inch from the welding (see directions on tube) and you can extend the length of the section you are welding because the cream blocks some transfer of heat to the panel.

 

I think the key to gas welding sheetmetal is to embrace the heat.

Instead of always fighting to not put any into the panel, learn to use it to your advantage.

Hot welds plannish faster, and a torch will pull a shrink about ten times faster than any other method. It does take a light touch to shrink well with the torch, but when you finally get your arms around it good, you'll save your shrinking disk for the days you don't already have the torch out.

Learn to use the heat to your advantage instead of fighting it, and you'll have a lot easier time overall.

I'm by no means a master, but I can tell you for sure that while I love my TIG machine, when doing sheetmetal work, I will pass it over for my little Meco torch every time.

I prefer to leave a gap between the panels with a width approximately equal to the diameter of my filler rod.

For filler, I keep ER70S-6 in 1/32", 1/16", and 3/32" OD on the shelf at all times, as well as the odd pound of RG45 and RG60, usually in 1/16" and 3/32" OD, and I may have a cannister of ER70S-2 in 3/32" OD as well.

I use the S-6 with the TIG, and since that's what is always out on the table, I tend to use it with the torch as well. However, the RG45 seems to flow a little better in the puddle, though that could just be my imagination.

 

just checked out the meco torch- i see one in my near future.. until then i'll practice w/ a 00 tip on my current torch and 1/16 rg45 rod and experiment w/ gap/no gap ... thanks

 

This is a great thread.
Have you guys got any comments on what torch you prefer and why????
Maco, Henrob/Dillon.................

 

If you're doing mostly gas welding, the Dillon doesn't make much sense to get...though it does make welding aluminum easier. I like the Dillon for it's versatility, clean cutting, comes with a "lead" tip, heating steel to bend, etc.
The Meco is so much smaller than anything else, it's the easiest to use.
But any of these is good for welding, practice with what you've got.
Can't add much to flathead's excellent post, but I will say tack your panels together, even hammering your tacks, and then do small sections at a time, welding and hammering. Once you get REAL good, you can probably weld an entire seam, then go back and heat and hammer it to perfection, but this takes quite some skill. Easier to control the metal as you go along.
Good luck, and practice, practice, practice!

 

Thanks Chopolds, I will look further into the Meco.

 

Victor makes a great little torch. It is the J27. I have used one about 25 years. Take a look at one at your welding supply. They dont cost what the Henrobs and others like it cost. They are light and small. You can get the double 0 and the tripple 0 tips for them.

 

Hey,

If you're gonna spring for the smaller sized torch like the Meco, be sure to get a set of the smaller gauges to go with them. I've found that the regular "journeyman'' sized Victor and the Smith's regulators don't run well at the light pressures used to weld thin sheetmetal.

I've always been a fan of "just tits" fit-ups using fusion welding whenever possible with the smallest filler rod I can get away with. Why add filler material you'll only have to file off later? I've even been known to cut strips of the "Parent Metal" I'm welding, and use that for filler rod!

I've moved over to the use of a "slapper" when bumping or shaping metal over a large faced bumping or finishing hammer. The face of a slapper moves more metal, and doesn't thin the metal as much as a bumping hammer might when working over an area. For repair areas that are torn, stretched or thinner than surrounding metal ,I like the slapper files.

When it comes to welding steel sheet or aluminum, pratice makes the master!

Swankey Devils C.C.
" Humpty Dumpty was pushed!"

 

I agree, Good advice on the gapping of plates. Metal needs a little room to move. Imagine a terd. Now imagine smashing your fist into the middle of that terd. What happens? Shit every where right? More precisely shit in a 360 degree circle. Like shit metal moves in all directions (360) when you strike it with a hammer. So having a small gap between your plates will give things (the metal) some room to move. Also have any of you tried torch welding with a jewelers micro torch? They have a very hot and precise flame and really keep distortion under control.