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Tomorrow I am picking up a vintage satellite dish 7' diameter free from a friend.  He claims it is 1/4+ thick aluminum mesh.  I plan on using a reciprocal saw to cut with a 9 teeth carbide blade using wd40 as a lubricant.  I have bent plenty of sheet metal but never aluminum.  I plan on bending it into a cone with 1' top diameter and 4' bottom diameter, then drilling and bolting together seam.  I understand aluminum cracks and do not want breaking to happen.  I want to bend the cone first and then cut out removable doors later.  Please share tips on bending without cracking?

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  I have no idea about cracking, the web may hold some insight to that but I wouldn't think it would be too big of a problem even if it did crack a little bit.  I am curious how you plan to bend it.  Around a form of some sort?  Are you going to flatten it first?  I wonder about too much stuff sometimes.  :)

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So no idea about the alloy?  Makes Annealing difficult.  Will you have scrap pieces you can experiment with and have you read up on torch annealing Al?  I would expect that for that usage they have left it pretty stiff to avoid sagging and incidental denting.  Further cold work may be an issue.

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Thanks for responding folks, progress as follows.  Picked up dish this morning.  Plenty of tin foil hat jokes with it transported on top of my truck.  Real thickness is 1/8” and 9’ diameter.  If you step on it it dents but springs back ito shape.  Center aluminum cover was welded to mesh; used angle grinder to weaken weld then hammered chisel through,  hard one hour of deafening pounding but only mesh left now.  Edges rolled for strength.  Have a brush burning torch to heat and bend maybe over log to get cone.  So once cone is achieved heat up over fire pit then cool quickly with water, is that annealing?image.thumb.jpeg.b0ed9959e0ef976f27eb3dde8a11ae8c.jpeg

 

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Will:  I have a similar dish lying in my yard and I have been trying to figure out a use for it.  I thought about a solar forge or a death ray but decided that either would have unfortunate side effects.  I am planning to cut it up and see if the local scrap yard will swap it pound for pound for carbon steel springs, etc..  My concern is whether it is too porous to direct the smoke over your fire pit.  Also, if the cutouts in the sides are high enough for you to easily access the fire.

Since the alloy is unknown you will probably have to experiment with how hot you have to get it, how long to hold it at that temperature, an how to cool it.  I suggest you cut up some small test pieces and treat them differently and see how they work.

"By hammer and hand all arts do stand."

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Will make cone first and then cut out one door and add the other two as pass trough.  Will smear fire clay and attach 12” pipe.  Will help with general smokiness.  Tips on bending with torch?

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Not sure on type of aluminum alloy.  When I used angle grinder to weaken welds to remove aluminum cap, had to be careful not to cut through mesh.  Seems soft when heated with angle grinder.  Mesh is strong but flexes with 20lb pressure.  Will use reciprocal saw and try to bend by hand /with torch heating.  Here’s a good laugh, wife said I am taking this tin foil hat thing a little too serious, pic.

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Aluminum comes in many different grades. T-0 can be bent almost like aluminum foil while T-6 is almost impossible to bend. I am not sure of the alloy being used right now but we are bending 3" x 1/4"  cold to make telegraph bases out of at work right now. (yes there is surprisingly still a market for telegraphs) 

The place of most concern will be the top with the smaller radius. That is kind of a no-brainer there. You can anneal the metal with a torch but keep in mind aluminum does not change color with heat, it melts from the inside out, and  aluminum oxide has a higher melting point than aluminum. That is important becuase all aluminum has a natural coat of it left on to protect the underlying metal from the elements. A quick look at my pocket reference says 500*F to anneal, but that is just a general rule and does not apply to all types of aluminum. 

When bending aluminum try and go diagonal of the grain, this will also help with preventing cracking. 

Now, i would have left it strapped down to the truck, taken it to the scrap yard and exchanged for the equivalent in sheet steel. 

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As already said, there's no telling what the alloy you have is, though you can try contacting the maker and asking. 

The old school not sure what the right temp is annealing method was to soot the aluminum and slowly heat it till the soot is gone. Just let it air cool, chilling it with water doesn't make the anneal, it's really more to get to work faster. It doesn't hurt but doesn't help.

Do you have a cable come along? If so you can wrap the pattern and use it to pull it into a cone. Just wrap the cable around the large radius, maybe use U bolts through the holes in the dish LOOSELY to act as guides. It'll probably most take something or the cable will slip off. Clip the cable to the come along and start winching. 

I wouldn't do any hammering, it work hardens aluminum quickly. 

It'll be pretty cool if it works out the way you think. Best of luck on it.

Frosty The Lucky.

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I asked the guy at work who deals with the purchasing and the like of the materials at work today. He told me that the aluminum we are using for the telegraphs is 3003 . He also told me that is the most common alloy you will will find for manufacturing of aluminum parts. He went on about ease of machining and the like, he is older and likes to talk, so i can not rememnber all the reasons, in all honesty i only about half listened after he answered me, but basically it is easy to work and machines very well. So it being the most common also means it is most likely the cheapest you can get. And being the cheapest...

Try taking a small piece and see how far you can bend it before it cracks. That should give you some kind of idea of if you can do his or not. 

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Worked all day in shop.  Reciprocal saw cut aluminum easily, then split dish in equal sections then cut off curled ring off bottom shroud.  Bent by stepping on inside and pushing, didn’t need come along.  Anealed over fire pit then moved outside and bent again by body weight.   Micro fit around fire pit and bent edges.  Added cutoff curl too.  Made fire much hotter.  Forged without gloves but still got too hot a few times.  Worked ambidextrous both sides of anvil, moving material constantly.  Ball pien hammer is fun.  Made point on poker, worked tongs, shattered aluminum motorcycle bonz, chainsaw carved djembe drum and drummed a little too.  Hands sore a good day.  Aluminum fumes?

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Sounds like you're having way too much fun in your shop. Glad that dish turned out to be easy to work. You might want to take a file to the cut edges before you or someone else brushes into it and christens it in blood.

You're going to use it to support a stone chimney right? I seem to recall you planning on using fire clay for mortar. It won't work, it'll dry and crumble unless you can fire it. You CAN however use it as component of proper mortar. What you want to do is what mortar is for. 

I used to remember the mortar mixes I had to mix and carry when I was 22 and carrying hod. I'd have to do a web search and I'm going to leave that to you. You want a fireplace or fire pit mortar recipe, some contain a little fire clay. Fire place mortars usually carry more sand than regular brick mortar does. I'm not going to try and remember more, it's been almost 50 years since I mixed mud. (YAY!:D)

Frosty The Lucky.

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Only on IFI would you find folk who not only know what a hod is but have carried one.  It would be better if your name was O'Frost since hod carrying is a traditional Irish-American occupation.

"By hammer and hand all arts do stand."

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On the east porch, I built a chiminea.  Took 55 gal drum, sawed top to cone wrapped in chain link fence.  Cut arch door added pipe and covered in mud.  The mix was 1/3 fire clay, 1/3 sand (filtered subsoil), and 1/3 Portland cement.  Still used today but has some cracks.

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I'm part Irish, just not the name part. 

I'll bet there are plenty of IFI members who'd think OyFrost would be more accurate. 

I see we're typing at the same time Will. Sounds like your mix is lasting well. If you add about 1/2 tsp of Elmer's white glue per 3gal to the water you use to make your mud it'll adhere better. We put it in the buckets of butter water too.

Frosty The Lucky.

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I didn't carry A hod, I carried mud in a bucket and packed cinder block up ladders two on each arm. I finally convinced the boss to load the scaffolding with the fork lift by just doing it. The masons called me the "hoddy" and the mud and block hod. One of them would yell, "HEY HODDY, MUD!" and I'd take off at a run. I did my best to stay ahead of them and occasionally scrape their mortar boards so their mud would stay smooth. 

I enjoyed the job but it beat heck out of my back, knees and arms at 22yro. Most of the masons had back problems. I looked for another career line.

Is that song a good drinking song? I'd kind of dig being in a drinking song. 

Frosty The Lucky.

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The song is "Finnegan's Wake", i have lifted more than one pint to in my time. Named after the Joyce novel. The song is about an Irish brick layer who falls from a ladder and breaks his skull. They have a wake where a fight breaks out and Tim Finnegan is revived when a barrel of whiskey is dumped on him. It has been recorded by like Goerge said the Clnacy Brothers, more traditional Irish music, to the Dropkick Murphy's , heavy metal Irish music. The Dubliners do a fun version of it where the audience participates. Another song the Dubliners also cover that mentions a hod is "The Sick Note". If you do not know that one look it up, it will put a smile on your face and giggle in your belly. 

I have listened to Irish music most of my life. I am one of the odd folks in the world that likes the sound of bagpipes. 

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Just ordered some refractory cement to trowel over the aluminum mesh.  This stuff should work until I can cover with rock.  Just need to use cinch straps to tighten up the top and add extra mesh to fill in transition to 12" pipe and bolt together by march 1st when cement arrives in mail.  Dries in one day.

Rutland Castable Refractory Fireplace Cement - 12.5 Pound Tub
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Billy, you are not alone in liking bagpipes.  I have had pipers at both my weddings and hope they will be at my funeral.  One of the things I like about Celtic festivals is that all day, near or far, you can hear bagpipes.  Sometimes it is a full pipe band performing or practicing and sometimes just a lone piper.

Bagpipes are used not just in Ireland and Scotland or even just Celtic regions.  They show up in traditional music in places like Lithuania, Germany, Greece, and various other places.  One of the legacies of the British Empire is that various miitaries around the world use bagpipes.  The Ghurka regiments in the Indian Army march to bagpipes.

"By hammer and hand (and bagpipes) all arts do stand." 

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