35 years ago before everyone and their brother had a wire feed welder and I became a master craftsman () a friend of mine brazed up the turn signal holes on another buddies VW bug then slathered them in mud. even then with no knowledge whatsoever about metalwork I knew that was just plain wrong. with affordable welders and everything you ever wanted to know about anything on the interweb with photos and video there is no reason for people to continue to braze anything on a car. doesn't matter that they did it like that in the old days, doesn't matter that you have 50 year old brazing on your car that has not failed yet.
Yep! Concentrate the heat on the flange more than the tube (pretty much necessary anyway) and the filler will flow to fill any gaps between the tube and the flange, top it off with a nice fillet on the surface and not much chance of the tube vibrating at that point. Roo
Nope, A Brazed joint has a tensile strength of about 34,000 psi while a TIG welded steel joint is about 85,000 psi Now that doesn't mean the joint isn't strong enough for the job, but is does refute your statement. Not true, Brazing is a process of joining generally applied to metal in which, during or after heating, molten metal is drawn into the space between adjacent surface of the 2 parts to joining by capillary attraction.The melting point of the filler metal is above from the parent metal. Braze Welding:- This process is similar to fusion welding. In this process have no capillary action. The melting point of the filler metal is below from the parent metal. This is the way the aforementioned Bicycle frames and Louts chassis were constructed. As a side note, not all Lotus frames were braze Welded. On the Lotus 7, Chapman used two suppliers ; Arch Motor did Braze weld the frames they built, but Universal Radiator Oxy Acetylene welded the ones they built for Lotus.
Horses for courses mate! Sometimes brazing is the best solution, more often TIG or MIG and sometimes good old oxy acetylene fusion welding. Roo
What's not true ? Braze vs braze welding? Maybe it a semantics issue where the term capillary is most associated with sweating pipes and the lead flows into the joint by capillary action. The bond between the lead and copper is a capillary bond. " Fusion welding" uses no filler or filler cut directly from the parent metal not rods and certainly not a dissimilar metal such as brass. IF you were to melt the steel and pool together with brass it will be very very weak. You see the tacks of brass in the op post? Those brass tacks stuck solely because of capillary bond. ( Dont confuse that with capillary action) At the surface area of the steel, the brass flowed in between the nooks and crannies of the steel. If it were a tight fit sleeved pipe and a fillet of brass were there, the bond between the steel and brass would be a capillary bond. If it were a loose fitting joint and brass flowed thru the joint because of capillary action the bond is still a capillary bond.
the hood of several old tractors ( AC WD's ) we had on the farm we brazed to repair them castings and the sheetmetal on the hoods , its where I learned the dip method ( and gas welding and how to heat shrink metal with a torch ) , and I still prefer to do this vs precoated rods , and I know the repairs are still good 35 years later on one of them and it was a user not a yard ornamant up till 2 years ago , and no cracks or paint pops , but when I was taught my grandfather made me use very diluted hydrochloric acid solution as a post wipe to remove the flux . since I have a mig I do not braze my panels in , but for other repairs like blocks ( welding on broken off tabs or fixing fins or cracks on small engines ) and the neighborhood kids bikes get brazed ( most bikes I have seen are resistance flash welded ( schwinns are known for this ) most are tigged now ( or psdo tigged ( migged to look like tig ,as I have found mig wire in the broken joints and the weld was Cold ) , only had one failure and that was way beyond the expectations of use , the bike was run over by a truck and broke the gooseneck
Don mentions the difference in bond strength between tig and brazed joints. In the early solar electric car tube chassis the MIT group used brazing. The reason I heard, was the area of the 'joint' was much larger, and it was far less likely to fail. (Even at 34K psi, when you've got more sq. inches to transfer the load, the brazed joint could be stronger.)
If you re-read, i said that the process was similar to fusion welding I did not say it was the same. I was attempting to distinguish it from the more common Brazing. The American Welding Society definitions for ”brazing” and ”braze welding” both stipulate that the filler metal must have a melting point above 4250C (8000F). However, the definitions state that in brazing the filler metal is drawn into a tight-fitting joint by capillary attraction; in braze welding the filler metal is deposited on the joint by other than capillary attraction. The basis for the braze welding process is that both brass or bronze will flow onto properly prepared surfaces of higher-melting-point metals or alloys to form a bond or molecular union which has excellent strength. The base metal is never melted. It is merely raised to the temperature at which the filler metal will tin– form a smooth film – on the surface of the joint. Although the temperatures involved are much lower than those required for the fusion welding of steel, braze welding is primarily an oxy-acetylene process. The intense heat of the oxy-acetylene flame quickly raises the base metal to the proper temperature for tinning.
Please show me one metal that has a melting point of - above 4250C (8000F). Just one will be good. Actually how about you just post a link to where your info is coming from. There's obviously at least a mistake or two- Maybe completely full of shit. It sure is written with weird word choice and structure. American Welding Society definitions for ”brazing” and ”braze welding” both stipulate that the filler metal must have a melting point above 4250C (8000F). Maybe you might want to re-read your postS Not true, Brazing is a process of joining generally applied to metal in which, during or after heating, molten metal is drawn into the space between adjacent surface of the 2 parts to joining by capillary attraction.The melting point of the filler metal is above from the parent metal. Braze Welding:- This process is similar to fusion welding. In this process have no capillary action. The melting point of the filler metal is below from the parent metal. This is the way the aforementioned Bicycle frames and Louts chassis were constructed. The Brazing process (slightly different from braze welding formerly known as bronze welding) is a similar connection to that of solder, the difference is the temperature required to do it. It is NOT a bond on a molecular level, its a surface bond. Its strong but there's no mixing of molecules, there's no blending of metals, theres no new alloys created in the joint! An easier to understand example of the mechanics of this bond is to take 2 pieces of steel or glass or styrofoam , hell try some rags too and wet them with water. Put them together in a lap configuration and They will stick but come apart easily. The water sticks to both and the water to itself. Now put them in the freezer so the water freezes together and try to get them apart now HA !!! Post a video The Braze welding process formerly known as bronze welding differs from brazing in the design of the joint only. The temperatures are the same, the fillers are the same the melt points are the same and the bond is the same. Again No molecular involvement. A lapped joint would be brazed while an open butt joint would be braze welded. Picture the lap plates 1/2" thick or 19 gauge- Build A fillet joint on the lap you just brazed and that would be braze welded. The transfer of filler into areas that you can't see or control are "brazed" and the build up of filler that you can see are "braze welded" If the term "braze" is in the connection description that gives you a definitive temperature range and the type of filler metal. there will be no melting of base metal. "Braze" has a higher temp range than solder and lower than welding, don't confuse "braze welding" with welding, remember why "braze" is added - to denote the temp range and "welding" because of the type of joint.
I remember working in a Chevy dealership body shop, while in high school, just before MIG and TIG machines were common, and we brazed everything, this was in the late 60's. So there is a lot of muscle cars with panels, holes, and rips that are not welded but brazed. I think the main reason was no-one could weld without warping the panel. The big thing was everything had to be real clean. I would just press the metal together and melt the rod on, while at the same time, with any luck having the surface metal hot enough to take on the filler. I think that most of the brazing problems came from dirty metal and guys just melting the rod onto the surface metal. Bondo would not really stick to the brass, but would stick together due to the amount we were using. I remember we only had one guy who could really weld and lead, the rest were just like me, no much in the way of skills. also the rod was flex coated.
i believe its not a about brazing method lasting,brazing has a place for the correct applications and is used today.Hacks used brazing back in the day for poorly joining panels together,it still joined the overlapped panels together,did it give the desirable finish?to some yes ,to most no.It's still is going to last as long as the method is done correctly.
Pretty much my point. In practical terms for the sort of work we are talking about (hot rods etc) there is very little chance of a properly executed brazed joint (nickel, not regular brass) failing. A long time ago a friend of mine had an off track excursion in his mild steel framed, nickel bronze welded dragster. In the process he ran over a rock sticking up out of the infield and tore every cross member in the bottom of the chassis in two but not a single weld junction failed. Just over 20 years ago I repaired the front frame section from a D type Jaguar that had crashed. Again there was a lot of tubing damage and distortion but not a single instance of failure at the brazed joints. Note that I said "properly executed". As with any form of welding some degree of operator skill is required. As with MIG welding, too little heat will leave the filler material sitting on the surface without sufficient bonding while too much heat can scale up the parent metal surface with the same result. Electric resistance welding (Stick, MIG and TIG) should be pretty much moron proof but in my business I see plenty of chicken shit welds with either no penetration (mainly MIG) or way too much heat (TIG) that has killed the molecular structure of the parent metal in the HAZ. Roo
This post sure did take a turn....All I was doing was showing you all that sometimes shit just does it's job, like keeping two panels together. Unsupported, with no bracing, and a ton of bondo (another thing you "just won't work") this Deuce 5 window has been on the road for at least 40 years like that. It was probably done in a dirt floor one stall garage somewhere in Iowa, or Wisconsin...far from where all the "experts" live, but it worked and held up well. No witness lines anywhere. I explained why it was cut out. I will guarantee if you were to grind or chisel, like I did, all the bondo out of many of these old time builds, you would find more work just like this. Will some of the modern welds still be holding up as well in 40 years?
I agree 100% with the OP. Brazing is old school and it works. I took welding in high school and had to learn brazing before welding. We used bare rods with the can of flux. I still braze stuff sometimes because I can. Something about making shit with fire.
Its the individual and their grasp of what they are doing. It's not the location or the environment they are working in
Not true, Brazing is a process of joining generally applied to metal in which, during or after heating, molten metal is drawn into the space between adjacent surface of the 2 parts to joining by capillary attraction.The melting point of the filler metal is above from the parent metal So according to this definition the filler material melts at a higher temp than the parent material. Therefore the filler material will be joining two blobs of parent material since the parent material will melt before the filler material reaches its melting point? I would LOVE to see that!
Beaner don't you think the exhaust thing might be more from temperature than vibration. Brazing is a lower temp process and exhaust systems can glow red.
Brazing has its place. Consider furnace brazing. The early Crosley blocks were sheet metal, furnace brazed. Mercedes mid 50s GP straight 8 had furnaced brazed cylinders and Desmo valve gear. I believe they had pressed together crankshafts.
look at / google MIG brazing @49ratfink it is becoming the new and required way to weld panels on new vehicles that have been in a collision. weren't most cars quarter panel joints at the roof brazed at the factory then leaded over in the 70's?
I have an O/T Mazda pickup truck (circa 1991) that has the roof panel brazed on from the factory. There are a LOT of things on that truck that have "failed", but the roof joints are perfect, just as they left the factory...
Yes they were, long after the 70's I might add. Silicon bronze for the most part. Most just in the outermost corners.
modern collision bodyman here. A couple years ago they switched the manufacturer recommended panel sectioning procedure from butt weld with a backing plate to MIG brazed with silicon bronze. less panel distortion (less bondo/material cost) and less corrosion protection burn off. Heres a photo of the joint. grind it off with 36 grit and bondo right over it....
From 1939 on Schwinn racing frames and Super Sport and Paramount frames were made of chrome moly tubing, butted together and brazed (no lugs). Thousands of air frames were made the same way. Not because it was cheapest but because it was the best and strongest with the technology of the times.
Repairing old cast iron exhaust manifolds (where the carbon may have been burned out of it, and the silicon oxidized, producing "burnt" cast iron that breaks rather than melts, more or less making it impossible to weld).
If you mean a well controlled TIG, O/A, or MIG with S-2 (E-Z grind) wire, metal finished and proper corrosion protection inside and out, final finished in current urethane paint, then cared for like nearly everything on this board? No. It will be holding up better for over 50 years Like some of the far out Kustoms of the 60s, just because you can doesn't have to mean you should. And as to some of those kustoms still looking good well past their heydays, their slang name of "leadsled" should explain it. Tinned brass holding solder is a no-brainer, lead gives and takes where gobs of good 'ol bondo does not. Exceptions to the norm are everywhere, and the norm is that welded steel joints are superior.
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