Brazing: Flux coated orf bare rod?

For bikes, (your name is familiar) paint a thin coat of paste flux on the joint and don't put any on the rod. I recommend GasFlux Type B (Blue) flux from

Soaks right off in hot water.

Hank also carries GasFlux C0-4 brazing rod, which is what most framebuilders use for fillet brazing.

You will get an idea of how much you need with experience. You can see the molten glass appearance of the flux when you are brazing, When you can't get a wetting action it is time to add a bit more on the end of your rod. I prefer flux in a can and bare rods. Coated rods seem to be so much more common. Randy

I tried a bare rod with a little flux from a pot and it flowed nicely and was much cleaner. Cheaper too!

My question: How much, if any, flux must be used to braze succcessfully?

If you do not use any flux, are you giving up strength for cleanliness?

BoyntonStu

I've got the Blues.

I have observed wetting on clean joints, no flux!

Have you?

BoyntonStu

BTW At this point, I trust my brazing far more than my stick welding. It is my method of choice for mild steel tubing. The beautiful fillets give me confidence.

Stu, I assume you are still building bikes, and are therefore using tubes.

Because fillet brazing of tubing joints requires repositioning the work many times, a tube is no place to be learning how to lay down a fillet.

So before anyone starts on tubes, they should do a few of these, at different angles.

I recently put on a brazing demo/class for my bike club. One fellow had never even held a torch before. After doing a few of the test pieces above and watching me do a fillet joint he produced a structurally sound, if not to pretty fillet. His is on the left and mine on the right in I use a large neutral flame, but once I start to build the fillet, I only have the flame on the work part of the time. As soon as I add filler, I turn the flame away and let the puddle solidify before bringing the flame back to re-melt the leading edge of the puddle. Reorient the work often so that you are always working slightly uphill.

I am working on hybrid trikes.

At the moment this is what I am thinking about building:

A 2F1R (2 Front wheels and 1 Rear wheel) hybrid 2 seater which in Florida is considered a motorcycle.

(BTW see

for a 3 wheeled Buick and a Fox)

Not quite a Trihawk.

A 2 seater with about 10 cu ft of cargo space. Not a short micro car but about 105" wheelbase.

500-600 pounds of batteries up front. 65/35 weight ratio No power steering. Disk brakes. The jackshaft to mount the 3 drive sprockets will go through a hollow swing arm pivot. Regen (possibility) and disk braking in rear. Weight under 1,500lb (hoping for 1,200) Roll cage protection using square 1018 1-1/2" .095 tubing. Frame/roll cage designed to force the batteries and the engine/motor to go underneath in a head-on collision. Fabric or other lightweight body panels. Engine/tranny is from a 1981 Kawasaki 550 GPZ. Engine on right side with chain to jackshaft going forward. Front end and manual steering from a Nissan compact pickup truck. 10-20 HP ADC motor on left side.

For the dimensions given, square is 1.7 times stronger in bending, has

1.7 times less deflection in bending and is 1.3 times stiffer in torsion. It also weighs 1.3 times as much per foot. Note: Contrary to "popular" opinion, round is *not* stronger for it's weight.

A 1.5" OD square tube of the same metal area of its cross section as a

1.5" x 0.125" round tube would have a wall thickness of 0.09616". This

would then be the same weight per foot as the round tube and be 1.4 times stronger and stiffer in bending but only 0.96 times (4% less) as stiff in torsion.

BoyntonStu

Three wheelers are considered motorcycles in almost all (if not all) states in the US. I've been riding motorcycles for 40 years. I know a little bit about them.

-- Jack