Gotta build some shelves. Gas weld or braze? (for the practice)

[Sebculb]

Hey everbuddy,

So I gotta build some generic metal storage shelves. Probably 1" square by 1/16" thick wall tubing. If I wanted it done fast and right (like for a client) I'd just stick weld it. But I'm still trying to learn how to use my new torch kit better and I can get a lot of good practice doing non-critical jobs like this.

Sooo, for those with oxy torch experience, should I just keep welding it using acetylene and concrete tie wire as filler rod? Or should I consider brazing it with bronze and perhaps hook up a propane tank to save money on acetylene (acetylene is very expensive here) and also just practice with all the different options?

Why flux covered brazing rod? I've been using soldering paste with a tooth brush on the few things I've brazed and it "tinned" and stuck fine. Been genuinely surprised at how strong brazed joints are.

Would brazing like this be strong enough for butt joints on utility shelves? This tubing isn't hot dipped galvanized, it's like the thinner zinc anodized coating and welds fine with no extra prep. Does anyone know if bronze will stick to it also?

Thanks!

 

[BCinVA]

I learned to weld by pushing puddles with an oxy/acet torch. It was all I had at the time. That experience served me well when I later moved to stick, then MIG and TIG. Just like DL Meisen in the post above, wire coat hangers was my filler rod of choice. I still actually have a bottle cart made from black pipe, that I welded with that first Oxy/Acet set. It is about 50 years old. (telling my age LOL). I would use whatever was fun. If you start with one you could always finish with another if you decided to. These days with the cost of gas, stick would be faster and cheaper, but as long as you get good welds, just do what you enjoy the most and fits the budget.

 

[etpm]

Hey everbuddy,

So I gotta build some generic metal storage shelves. Probably 1" square by 1/16" thick wall tubing. If I wanted it done fast and right (like for a client) I'd just stick weld it. But I'm still trying to learn how to use my new torch kit better and I can get a lot of good practice doing non-critical jobs like this.

Sooo, for those with oxy torch experience, should I just keep welding it using acetylene and concrete tie wire as filler rod? Or should I consider brazing it with bronze and perhaps hook up a propane tank to save money on acetylene (acetylene is very expensive here) and also just practice with all the different options?

Why flux covered brazing rod? I've been using soldering paste with a tooth brush on the few things I've brazed and it "tinned" and stuck fine. Been genuinely surprised at how strong brazed joints are.

Would brazing like this be strong enough for butt joints on utility shelves? This tubing isn't hot dipped galvanized, it's like the thinner zinc anodized coating and welds fine with no extra prep. Does anyone know if bronze will stick to it also?

Thanks!

Hey everbuddy,

So I gotta build some generic metal storage shelves. Probably 1" square by 1/16" thick wall tubing. If I wanted it done fast and right (like for a client) I'd just stick weld it. But I'm still trying to learn how to use my new torch kit better and I can get a lot of good practice doing non-critical jobs like this.

Sooo, for those with oxy torch experience, should I just keep welding it using acetylene and concrete tie wire as filler rod? Or should I consider brazing it with bronze and perhaps hook up a propane tank to save money on acetylene (acetylene is very expensive here) and also just practice with all the different options?

Why flux covered brazing rod? I've been using soldering paste with a tooth brush on the few things I've brazed and it "tinned" and stuck fine. Been genuinely surprised at how strong brazed joints are.

Would brazing like this be strong enough for butt joints on utility shelves? This tubing isn't hot dipped galvanized, it's like the thinner zinc anodized coating and welds fine with no extra prep. Does anyone know if bronze will stick to it also?

Thanks!

Well, since you apparently did a pretty good job brazing your last job, even adding an extra steel piece to replace the cast iron that went away I'm thinking your brazing ability is probably OK. However, I think maybe a little more education might help regarding brazing. First of all, there are several fluxes you can use for brazing. Some of these fluxes uses water as the medium to carry the actual flux. Others use alcohol. Then there are dry fluxes. These can be in powder form or can be a coating on the brazing rod itself. Any of these fluxes can be used for brazing. I, myself, like to use the powdered type of flux that is used with hot rods. The rod is heated and dipped into the flux. This causes the flux to stick to the brazing rod. The flux can also be sprinkled onto the work once it's hot and it will stick and start to melt and so cover the area to be brazed. The important thing is for the flux to melt and cover the work, and then the brazing must be done as fast as possible so that the flux can do its job of absorbing oxygen and cleaning the area to be brazed of oxides and other dirt.
Let's talk now about terminology. You have mentioned more than once about using bronze for your brazing. Most common brazing rod is not bronze. It is brass. Even though the designations between the copper alloys of brass and bronze can be ambiguous, when it comes to brazing the differences are pretty clear. Brazing alloys are predominantly copper and zinc. This makes them BRASS. When the copper is mixed with other elements it becomes BRONZE. When you are using a bronze alloy for brazing then you are bronze brazing. Clear as mud, right? Because the boiling point of the zinc in BRASS brazing rod is so low it is usually only used with a flame. The BRONZE brazing alloys usually have elements with much higher boiling points and so they can be used with a TIG torch. You don't care, you are using a torch. I'm just being didactic. The most common BRONZE brazing alloy is silicon bronze. It is about 97% copper and 3% silicon. And it is about as strong as mild steel. There are many bronze alloys used for brazing. Aluminum bronze and silver bronze are common alloys. They are quite strong, over twice the tensile strength of mild steel. I think, from the color of the pictures you posted in your cast iron repair thread, that you were using brass brazing rods, not bronze.
Maybe, finally, to the meat of the matter. Your brazing right now seems to be at least sufficient because your cast part repair seems to be working. Welding. If your gas welding looks bad then you need to practice no matter what acetylene costs. Regarding your filler metal of choice, hmm. When I was learning to gas weld I was 13. I went through rod fast. I figured out, as have countless others, that the steel coat hangers of the day made good welding rod for welding mild steel. I weld repaired many lawn mower handles in our nneighborhood. Decks too. With coat hangers. I cannot speak to how good your particular filler wire choice is. You will need to evaluate it. Make some welds. Break these welds. Understand how they broke. Were the breaks brittle? Did they instead stretch a bunch before they broke?
I spent many years of night school learning how to weld. I mostly did this because I wanted to learn about and understand welding. I got good at it. I made money with my learned skill. I never had a job returned for a bad weld. None of my welds failed in the field. With practice you too can do this because good welding on most stuff is achievable by most people. With enough practice.
Cheers,
Eric

 

[rScotty]

Hey everbuddy,

So I gotta build some generic metal storage shelves. Probably 1" square by 1/16" thick wall tubing. If I wanted it done fast and right (like for a client) I'd just stick weld it. But I'm still trying to learn how to use my new torch kit better and I can get a lot of good practice doing non-critical jobs like this.

Sooo, for those with oxy torch experience, should I just keep welding it using acetylene and concrete tie wire as filler rod? Or should I consider brazing it with bronze and perhaps hook up a propane tank to save money on acetylene (acetylene is very expensive here) and also just practice with all the different options?

Why flux covered brazing rod? I've been using soldering paste with a tooth brush on the few things I've brazed and it "tinned" and stuck fine. Been genuinely surprised at how strong brazed joints are.

Would brazing like this be strong enough for butt joints on utility shelves? This tubing isn't hot dipped galvanized, it's like the thinner zinc anodized coating and welds fine with no extra prep. Does anyone know if bronze will stick to it also?

Thanks!

The bronze will be more than strong enough and with a little practice will make beautiful joints. I'd prefer bronze brazing for 1/16" tubing. It will flow over some thin zinc, but it is always better to file or sand back a ways. Give the bronze 1/8 to 3/16" inch for it to allow to steel without any zinc in the way. That applies to welding as well.

Brazing uses very little acetylene compared to torch welding. A tank used for brazing lasts about forever. I run 5 to 7 psi acet. for small brazing & about 10 to 12 psi oxy. You don't need a big flame. A small hot flame works best for brazing. If you can hear it, it's borderline too large of a flame. You want a small enough tip orfice to keep the gas velocity up at those low pressure so that the flame doesn't pop and back burn in the tip.
You can resize brazing tip orfices somwhat by putting in the next size smaller drill bit shank and gently hammering on the sides of the tip. If too much, you can drill them out larger again.

One of the things that makes torch welding and brazing so nice is that the light is not so intense. You can watch the alloys form and even reposition them if necessary.

Welding and brazing are just practice. Good brazing is nearly as strong as a weld, and can be even stronger than welding if you shape the joint to include more flats so it an take advantage of the way brass flows between surfaces. Also, once you put in the practice learning about brazing, you will find that it is the best way for joining cast and some alloys.

Brazing on the flat is the way to learn. So I recommend you do first projects flat on the bench if you can. If you have wire feed or TIG, You can also tack weld something in place and then move it to the bench for final brazing. You will eventually learn to to braze up and down or overhead against gravity - but TIG or Wire feed tacks are good positioning in place. You can braze right over the tack.

BTW, hi-nickle or bronze brazing rods make much stronger joints on more materials than the low cost old-fashioned brass rods and are easier to use doing uphill or vertical work.

I hate pre-fluxed rods. That's also about 100 times more flux than you need to be using unless you are doing rusty oily metal. That much flux only causes problems. Pre-fluxed rods are a huge impediment to learning to braze properly. The other impediment is not using the right flame, pressure, and too much heat. You want a light red heat in the steel - just enough to make the bronze flow smoothly. DO NOT SCALD THE BRONZE! If it gets too hot the surface of the braze joint will begin to look fizzy. You can fix that by adding more flux and bronze rod until the surface smooths out again

If pre-fluxed rod is all you can get, you can hammer the flux off. It's a pain, but worth doing.
Flux is necessary, but in very smaller amounts. For fluxing I lightly heat the rod or joint and then sprinkle on minimum flux using an old salt shaker.

That's about it. Take the time to learn brazing. It's an art, and very versatile. It's a great way to practice your fine brazing and torch control.
Best of luck,
rScotty