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Old 01-11-2018, 03:44 PM
elavir elavir is offline
MetalShaper of the Month May '17
 
Join Date: Dec 2014
Location: Holland
Posts: 157
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Quote:
Originally Posted by Stretch View Post
Hi Richard.

For aluminium (16 gauge) I would highly recommend trying either a no5 or no7 BOC style (UK) welding nozzle and, most importantly, turn the gas pressure down to 2-3 psi max. You want a soft, fat flame. A lot of beginners make the mistake of running a too narrow flame cone, with higher than necessary flame pressure, which inputs too much heat into a thin weld zone causing burn through. Also, you have to weld aluminium at a very quick pace with oxy-acetylene. We are talking almost feet per minute as opposed to inches per minute a la steel. This is where the true art to gas welding ali comes in to form. Fast, fast, faster!

I seldom add rod to the puddle on ali body panels - for me the rod is there literally to start the weld then finish the last 1/4" of weld.

Also, I was taught to oscillate the torch in continuous circles to the width of approximately 1/4" - 3/8" around the weld zone as you move the torch along its path. This, apparently, was the norm during WW2 era to decrease the intensity of the heat affected zone according to my mentor. It is said to even out the h.a.z. a little, which reduces stress. This method, with good practice, should produce a lovely, flat bead with perfect penetration: A weld that needs no filing and only planishing or wheeling to make the weld virtually disappear.

Don't get me wrong, there are many ways of gas welding aluminium, but this is what I was taught and I find it works fantastically well.

On a side note... and this is one that's sure to raise eyebrows: I only flux the edges of the metal and not the full width of the weld bead. I find there is more than enough flux on just the edges to facilitate a perfect weld. The advantage is that flux glare is massively reduced and you have a more even temperature distribution. Again, a nugget that was passed down to me during my apprenticeship in the 1980's.

Regards, Matt

Hi Matt, thanks for your explanation and tips.
One thing that I don't understand is the oscilating of the weld. Is this done after welding?

Cheers Richard.
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Richard
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