O/A welding aluminum

[Stodtmeister]

I've recently decided that I needed to add O/A aluminum welding to my skill set and I'm having some issues I'm hoping someone can walk me through. First of all, I'm using the Cobra DHC-2000. O/A are both set at 4lbs and I'm using a .5 tip with a neutral flame. I'm practicing on .063 5052 aluminum and have been trying some 1100 wire, some 4043 tig rod, and even some thin strips of the 5052 as filler rod. My flux is the super premium aluminum flux for gas welding sold by tinmantech.

The coupons I'm using are new aluminum, but still I'm cleaning them with a new stainless brush and rubbing alcohol and applying a healthy amount of flux to both coupons and the filler rod. My problem is that as the metal starts to pool, it is almost repelled by any other molten aluminum it comes into contact with. My filler rod tends to just bead up on the coupons and not actually intermix with the pool. I'm assuming it's a flux issue, (operator induced obviously) but when I introduce a flame, the flux just kind of dries out and never really liquefies like I think it should. Not sure if it's a heat issue, but clearly I'm doing something wrong. Any advice you could send my way would be a big help.

Regards,

Scott

[Ltbadd]

Scott, welcome to the forum.This may be a good question to ask the flux supplier if no one here can answer, I would guess using o/a to weld aluminum isn't very common.

[aametalmaster]

I see guys using Hydrogen/Oxygen rigs. The blue lens glasses is the critical part...Bob

[piniongear]

When I was a 17 year old motorcycle racer I worked at a BSA motorcycle shop in Houston Texas.
I broke a rod in my BSA Spitfire scrambler at a race and the rod punched a hole in the bottom end cast aluminum crankcase.
The hole was about the diameter of a golf ball.
The owner of the shop (Bruce Bristol) told me to go in the back of the shop and find the old set of Golden Flash crankcases.
He showed me how to drill a series of 1/8 inch holes in the same area of the GF case and then knock the plug out with a small cold chisel.

Having done that he then told me to sand the plug smooth and shape it as close to the hole size as I could.
I got it pretty close and it stuck in place in the Spitfire case.
Bruce said, now we are going to weld it up.
He then said..... 'Not we... you are going to weld it up.
I had never done any welding in my life at that point.

Bruce told me the aluminum would melt through without warning if I got it too hot. He cautioned me several times about this.
He told me to clean the pieces completely and then to scrub them with a stainless steel brush.
He fired up the torch and handed me the liquid flux to paint on the surface and the filler rod.
He adjusted the torch flame with excess acetylene and as I recall the outer flame was about 1.5 times longer that the inner flame.
He told me to keep the torch flame about a 30° angle to the work and don't let the inner blue flame touch the metal.
He then walked away and said.... 'Watch getting too much heat on it".

The weld turned out perfect and did not even seep any oil 5 years later.
This was my first welding experience and I still remember the details like it was 2 years ago and not the actual 56 years.

So I would recommend you use the same methods Bruce showed me, keeping the excess acetylene flame.
In later years, Mig and Tig came along, and today all my welding of aluminum is using with Tig.

I had my share of problems learning Tig because it was difficult for me to get the hang of it.
But I often stop and think back to that shop experience with Bruce Bristol and chuckle at the thought..... Don;t tell a 17 year old he cannot do something.. He will prove you wrong every time.
Perry