Weld vs braze

[pminmo]

I'd like to be able to join metal. In college (30 years ago) I had a process class where we did some arc welding and brazing. I remember from that experience that my hands were not steady enough to arc weld. I seem to recall brazing ok. I do solder copper, insluding small electonics... My question is, maybe the biggest material I might want to join would be 1/4" x 2" square tubing. 1) Is that in the realm of brazing? 2) Is wire welding less forgiving to the unsteady hand than arc welding? Is there something else?

Thanks,
Phil

[murphy625]

Brazing will work..
Mig welding is faster and better..
A tig welder will do it all. (almost)

Mig is cheaper than Tig but tig can do aluminium where as its a hassle to use a mig..

Plasma cutter and tig welder and you can build anything.. (just about)

Mig is easier to learn than all others..

[mxtras]

I equate brazing to soldering. It works but you are killing the structure of the base metals - the joint is the weak link. It has it's place but not to join steel tubing or plate and especially not for any kind of structure.

I would personally suggest MIG for almost all steel and TIG for aluminum - period. If you had to choose only one, then go with MIG for economy or TIG for efficiency and versatility. MIG is very forgiving, but there is still some stuff you will have to learn to stick stuff together properly.

Some will say that TIG is slower but I strongly disagree. There is a difference in operating costs and weld time but the benefits outweigh the drawbacks for almost all odd-job kind of work. There is no post-weld clean up required with TIG. This can kill you with MIG.

MIG will get you sticking stuff together quickly for less money - aluminum, too depending on the machine. Like murphy said - MIG kinda sucks on small to medium thickness aluminum but is hard to beat on steel or thick aluminum (lots of variables - hard to come up with a one-liner on how to weld).

Sounds to me like you would be best served by a MIG wire feed welder. It is forgiving, economical and versatile.

Scott

[fyffe555]

Originally Posted by mxtras I equate brazing to soldering. It works but you are killing the structure of the base metals.

You sure about that? Brazing is at a much lower temperature than , say OA welding and while there's some detrimental effect from heating the base metal while brazing it's far less than OA welding and even more so than electric arc. Welding causes a region of material with a different structure immediately around the weld that can be a failure point if not considered or treated.

Originally Posted by mxtras - the joint is the weak link. It has it's place but not to join steel tubing or plate and especially not for any kind of structure.

Brazing doesn't have the ultimate strength of a weld, true, but its still plenty strong and entirely suitable for many steel tube or plate joints. In fact, because of the issue of brittle failure brazing used to be and occasionally still is the joint of choice where there might be flex or vibration stress, such as bicycle frames, chrome moly car or bike chassis, and aircraft structures.

Having said all that I entirely agree with your comments and suggestions on choosing MIG! By the time you get set up for OA, bottles, supplies etc a decent MIG is not much more.

Just don't anyone waste time and money as I did on a cheaper HF or name clone machine. Especially if you're thinking of AL as well.

Andrew

[pminmo]

If I limit my angle to 1/8" will this do a decent job to get me started?

http://www.mylincolnelectric.com/Cat...eet.asp?p=8957

[mxtras]

Yeah - I'll stick to my story.



Scott

[mxtras]

OH -NO!!! Don't limit yourself!!!

jk - budgets suck, huh?

If that machine maxes out on 1/8" and you plan to weld 1/8", then I would suggest you get a slightly larger machine - it would be like running your car near redline on the way to the grocery store...it will go, but what's going to fail? Watch out for the duty cycle rating, also. ...and make sure you have a circuit in your shop that can supply it with enough electrons to keep it happy.

There is a company that sells brand new Miller equipment on Ebay - free shipping and their prices are really, really good for machines - I would suggest that you dig into that before you commit. You can probably find Lincoln on there, too. Just a thought. I paid over $4400 for my Synchrowave locally and this Ebay outfit had it for $4100 with free shipping....I found it too late.

Scott

[jderou]

Brazing might be at a much lower temperature than welding, but for this reason your heat affected zone (HAZ) is MUCH larger. High rate of heat input = small HAZ, low rate = large HAZ. the larger the haz, the more you have weakened the base metal.

[ynneb]

The many advantages with mig welding are,

What you see is what you get. ( No slag covering up a bad weld)
Much more setting controls , variable voltage, feed rate, variable current, different gas sheilds to suit different metals.

I only own an rod arc welder, but when I did a mig welding course I got to use a mig welder. There was one time when I accidently put a tack weld on the join but it was in the wrong place so I had to break the weld and move the piece. I literally did a 2 second tack weld, but it was almost impossible to break off by hand. If I had done the same thing with a rod welder I know from past experience it would have been very easy to break the same sized weld.

Rod welders are notorious for burning through thin materials if you are in experienced. Mig welders can be much better to tune for the materal thickness you are welding.

The biggest thing, and I know I have already said it, is no slag, no need to clean the weld.

[mxtras]

MIG is relatively clean and fast - and the easiest to learn for welding steel IMO.
TIG is the cleanest and most versatile with a slight welding speed disadvantage.

I have been MIG'ing and TIG'ing structural aluminum (6061) for the past 5 years and I can say that for fillet welds on thicker material (1/8"+) MIG does fine but the learning curve is substantial. It took about 8 months for me to be able to lay down a good quality, good looking MIG weld consistently - and I purchased a top of the line, industrial sized, dual gun Miller MIG and I have more than adequate training and experience. If everything is right it is possible to lay down a brite, shiny fillet weld with very limited spatter, but there is always some and the starts are ALWAYS cold with the MIG. MIG sucks for butt joints in this aluminum - period - it sucks. If you are considering welding aluminum, consider TIG.

....sorry - I am just bored, guys.

PMINMO -

Did you select your machine yet????

Scott

[OCNC]

Originally Posted by pminmo If I limit my angle to 1/8" will this do a decent job to get me started? http://www.mylincolnelectric.com/Cat...eet.asp?p=8957

I've got the 125 amp version of this Lincoln unit and use it exclusuively with flux core. (My machine runs on 230v and looks exactly like the 135 model.) I had it set up to run MIG but found that it was somewhat 'toy' like compared to larger MIG machines so I went back to flux core. For me the machine really shines as an 'always ready to go' flux core machine. (I don't mind the slag. If you get the current and feed set correctly and the metal is clean the slag is hardly an issue as it comes off easily. You do have more fumes to deal with using flux core.) I regularly weld 3/16" structural tubing without maxing out the amperage. Having a steady hand is probably a matter of practice and technique. I like to think of the weld puddle as a crucible of molten metal that I keep filled and move ahead as it starts to overflow. If it isn't about to overflow I don't move it ahead. At these low amperages you can go bare handed or wear a light leather glove on the torch hand and use a long gauntlet weldors glove on the other hand. You can use the heavily gloved hand to guide torch tip without a risk of getting burned. Use a helmet that has an automatic darkening lense and use a magnifying insert. It's important to be able to see what you're doing. As you get experienced you'll realize that you can also tell a lot about the weld by the sound that is being generated by the arc. Don't forget that the arc produces strong UV. Protect your skin. The other thing to remember is that welding is similar to painting in that preparation is key. Clean metal is a must so get a small 4" grinder and an assortment of abrasives.

Chris

[CNC Pro]

I own a hand made Italian bicycle, all brazed. Why would they braze rather than weld?