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I have a set of oxy/acetylene torches, and it has been ages since I used gas to weld, highschool 15+ years ago. I can stick things together, but nothing that can withstand worrying them apart (bend back and forth). I get tons of slag build up too. I've tried knocking back the oxy. for a more gas rich flame but that doesn't seem to help either, thinking that I was oxydizing the iron before it had a chance to mix (heh, forge welding seems a lot easier at this point). I've also tried a hotter flame as well. This is for the tree/bed project so forge welding the branches is not a practicle option. Any pointers for welding with torches?

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Dennis: It's all about the puddle. One of the advantages to learning gas welding, in my opinion, is that things move more slowly than electric welding, and you can watch the behavior of the steel as is goes from solid to plastic to liquid, which can help someone learning to forge-weld. So I guess, though it is a stretch, that this is an appropriate question in the blacksmithing forum. :)

Here are a few links:
Oxy-Acetylene Welding and Cutting by Harold P. Manly - Project Gutenberg
Welcome to the Manufacturing Forum: oxy-acteylene welding filler

To successfully weld, the metal MUST be joined in the puddle. If it is all blobbing up an you, then you might not be actually melting the pieces. Use the filler rod very sparingly. Sometimes, you don't even need a rod. In any case, the two pieces should be molten and THEN the filler rod is melted into the existing puddle. If you don't have the parent metal hot enough, when you approach the flame with the filler rod, it will melt in a blob and stick like a bugger on the pieces without actually fusing anything.

Try welding some practice coupons using different tips and angles and pressures till it starts to feel right.

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Some things to watch...

1. Correct size tip
2. Clean tip
3. Clean material - start with no forging slag or rust on the parent stock.
4. Use real welding rod - not coat hangers.
5. Watch the distance from tip to work - too close will pop and blow the material away.
6. As Ed said, the puddle is important - get both sides of the puddle formed and add the filler rod.
7. Use a neutral flame - it should not make a nasty mess.

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Neutral Flame & Clean tip
Open Torch Acetylene valve 1/8 turn light torch- black soot will come out.
Increase the acetytlene till soot stops.
Then open oxygen vavle 1/8 to 1/4 and adjust for a nutral flame.

This is what you want = Neutral Flame 1 light blue cone at tip no hissing

Gas Rich = Carburizing- large light blue with a very light green outer feather no hissing

Oxygen Rich = Oxidizing- small white cone & loud hissing

Hold torch about 1 inch away -Steel should start to turn red with in 5-10
seconds if not you are not holding it close enough or the tip isnt large enough
for the metal thickness.

I havent done much Torch welding but some , got to have a neutral flame.
You can weld with out rod Fusion.
TC 9-237 Chptr 11 Oxygen Fuel Gas Welding Procedures
Oxyacetylene Gas Welding - Engineers Edge

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Hi Dennis. I also took a high school metal shop class. The instructor taught oxy-ac welding in two lessons, which included flame cutting. The most important part is making a neutral flame. He spent a lot of time explaining why this is important and how to merge the inner cone and the acetylene "feather" to achieve it. Second, use the correct tip size. If the tip is too small, the temptation is to go oxidizing to get more heat. That's how you get the slag. To fix this problem, ask an expert or consult a tip chart. We were making puddles the first day and passing bend and break tests on coupons the second day. I skipped the test and made a watering can out of a bean can. No way you can do that with a stick welder, but you can do just about everything else :).

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Well, today I got a very nice weld on 16ga plate and learned that the tip to do that is not the same tip to weld 1/8" plate which was explained above. That tip oxidized the plates together and it broke apart with a tap from the pliers. Is it a practicle thought to use gas to weld branches together for the tree and to fill the gaps?

I see the links, checking them out now.

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OK here goes. FIRST, acetelyne welding was used for many things in the past. Aircraft frames to gas mains (underground). It is still used in many areas. Acetelyne welding works well on rusty stuff where electrode (rod or wire) won't sometimes. I'm speaking welding not brazing here. Close both bottles. Back your regulators off and drain hoses. Open both torch valves wide open. Select tip for welding project ( this will vary ). A stand or a vise (clamped extremely lightly) will hold the torch. Open Acetelyne bottle. Sparker in opposite hand, slowly screw in acetelyne thumbscrew with other hand and spark torch head until you get it lit. Torch head should obviously be pointed away from flammable stuff. Increase thumbscrew on regulator until smoke dissapears (barely). Now, open oxygen bottle and screw oxygen thumbscrew in until you get start of a little blue cone at base of torch fire. Advance oxygen thumbscrew until you JUST make the cone stand alone ( read no feather around it ). If you have acetelyne training, you know what I mean ). Feather is the thing to be rid of and proper fuel pressure is what stops internal torch fires. You should now have fire necessary to torch weld with a neutral flame. This should end up around 4 to 5 lbs pressure on each torch guage. Close torch valves and now are ready to re-light with proper regulated pressures. Never vary from this setup and flame configuration and you should have good results welding. Technique of welding has been discussed. Good joint and you need no rod, yes, but I still have one in opposite hand from torch most of the time anyway. If you do not have check valves on torch setup, GET THEM. If you have no bottle and torch training, GET IT from an accredited trainer. Bottles are missles and acetelyne is extremely dangerous as is oxygen in untrained hands. Leak check is necessary. Good luck and have fun. Tip size will yes make a difference.

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Lots of Pro Welders here
I know very little about welding but learning but-

once you get a NEUTRAL FLAME it will solve most of the problems.
The weldes will not be strong if not a NEUTRAL FLAME
NEUTRAL FLAME is the key
Look at the links & read Im sure there is a pic. of a NEUTRAL FLAME
If you dont have a NEUTRAL FLAME it wont work
This is the first step then you got learn about puddle- penatration -beads undercutting -joints- just to name a few.


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Sorry Dennis
dont take me wrong Im just tring to help.
I had a heck of a time with the torch until I got a neutral flame
Be Safe

No offense taken! Nuetral flame is the ticket. I got a pretty good weld on 1/8" plate today. I had to worry the joint apart with a hammer and a vise.
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