Reshaping an aluminum drain pan - anneal first? Suggestions please

I need to modify a round AL drain pan as used under a hot water tank for my rent house (code requirement). Due to space limitations (the entire house is only 600 sq ft), I need something that is oval shaped

- I am unable to move either the chimney or the furnace to gain more space for a larger dia. pan. My local sheet metal place can make a square one out of steel but because of a serious lack of room that will not clear the hot and cold supply lines. If I could find a round one in steel I could easily cut, bend and braze it. I have looking in Grainger and McMaster-Carr. As reference, a typical steel automotive oil drain pan is 16 inches in dia.

What I have found is an aluminum pan intended for use as a hot water tank drain pan, about 3.5 inches deep, that is 20 inches in dia. at the base and flairng out to about 21 inches in dia. at the lip. I need to make it have two flats, such that the width across the flats is 19.3 inches.

After I do the relief cuts, would there be any benifit in trying to anneal it prior to trying to rework the part? I do not know anything about the alloy used - I assume that it is something like 3003 (strictly a guess based on reading the various alloy descriptions in my metals catalog). The aluminum mics 0.031 thick. For annealing, all I have available is either a brazing or cutting torch. I have used the cutting torch with an acetaline rich flame to heat and soften similiar thickness steel that I was hammering to shape.

Then I still need to resolve how I am going to rejoin the cut pcs. I no longer have access to a TIG. I could give it to a welder - I hate to outsource something that is tangentially hobby related. I could buy the super duper $100 special lenses and try to gas weld it but I wonder if I would need a mini torch - I have an old Victor J100 w/ a

000 tip. Ideas/suggestions?
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Sure, don't weld it at all. Since it's not going to hold water(you hope) for any length of time, why not just make your cuts and bends and plaster the area with another chunk of aluminum and JB Weld? I suppose you could pop rivet them if you wanted, too. Should give you enough water-tightness for the job with the epoxy. It's not like it's going to have public exposure like a car fender does.


Reply to
Stan Schaefer

The rule of thumb for annealing aluminium in the back yard is to place soap marks on the piece with ordinary household soap. A couple of crosses will do. Heat the piece evenly with your torch from the opposite side to the soap marks and heat until the soap goes black. Quench immediately by total immersion.

Don't know why you want "relief cuts" it will move a long way. Make a wooden pattern (form block) of the shape you want. Clamp it inside the pan (use a backing piece where it already fits) and hammer it up to the form block starting where the the material touches the pan. Avoid wrinkles in the material if you can. You may need to anneal it a couple of times.


Reply to
Glenn Cramond (Glenn Cramond) wrote in response:

Make a

Thanks Glen. Using soap as a temp indicator is something I have never heard about and is just the kind of advice I need. Also I would never have thought that I would need to quench to anneal - I would have simply let the part air cool. I like your suggestion of "hammer" forming over a buck. My thought was to cut the verticle sides of teh pan where the flats will join the round sides, flatten that protion, bend straight across between the cuts and weld the seams. I like your suggestion better. And if I mangle things too much I simply cut away the area and weld in a flat piece. Once again, thanks.

To Stan, I am afraid your suggestion, though it would work might not pass the somewhat anal plumbing inspector. If up to me, I would skip the drain pan altogether. Considering that this 70+ year old Depression era shack (built with a lot of salvaged lumber) is still around, I'm not too worried about the need of a drain pan. Thanks for posting.

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