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13th Mar 2018, 08:11 PM #16Most Valued Member
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I have no idea what that is supposed to mean, other than a troll, and I stated outright I wasn't meaning to be pedantic. My point is that there is no such thing as "normal" aluminium (although some grades are much more common than others), nor is "pure" aluminium all that common from a machining/fabricating/engineering point of view. All will fall under a specific grade which almost certainly contain some form of alloy. What that alloy is will affect how suitable it is for the task, some for example are unweldable so if that's what your intentions were you're going to be SOL.
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14th Mar 2018, 10:39 AM #17Golden Member
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I have adjustment on the radius bar/fingers to move them back and forth so I have some control over the bend radius, in doing this chassis I did make the bend as tight as I could so that it would look the same as a steel chassis which is traditionally 1.6mm thick, the chassis will be and truly our of sight so in the interest of good metal work I probably should increase the bend radius, just a matter of bending a few annealed test pieces. Thanks Pete for the PDF link - reading it I see that 5052 can be annealed by heating to 345 deg it's not that high so I might even get away with using a map gas torch.
For those interested the amp is for guitar, and a copy of an early 60's Vox AC15 combo for my son, 50 yrs of messing around with electronics means I should be able to build it and not have to buy a single item. I was an aspiring guitar god in the late 60's the only problem was I had no talent, that did not stop me from blowing all of my school holiday casual factory earnings on a secondhand Les Paul custom, my parents hit the roof when they found I had spent the whole $110, the guitar ended up languishing under the bed as they do in situations like this. I tried to sell it few times when I was short of money and at one time I was even desperate enough to offer it for $20, luckily the guy knocked it back saying he was suspicious of the low price. It's now with my son and I believe worth close to $10k, he has the talent that I never had.
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14th Mar 2018, 11:23 AM #18Most Valued Member
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Wow, I'll give you 20 bucks for it, no problem
Let us know how you go with the annealing, I've never tried it on aluminium only read about it. The temperature range is definitely within a domestic oven's, though the sheet it probably too large to fit.
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14th Mar 2018, 02:31 PM #19Senior Member
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As well as setting the fingers back from the bend, you can place a sheet of thinner material on top of the aluminium sheet you are folding. This can be steel or aluminium, or even plastic. This will have the result of increasing the bend radius of the aluminium you are trying to fold.
Year's ago, when I built a few aircraft, I made a series of radiused spacers that went between the fingers and the sheet to be folded. They had defined radii so that parts met minimum bend radii stipulated in the relevant aircraft standards. But you can produce a similar result using the thin sheet metal trick mentioned above.
Graham.
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18th Mar 2018, 10:08 AM #20Golden Member
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More on the bending stress lines.
Needing a small bracket for my amp project I first annealed the aluminium (with a map gas torch) and bent it used the same settings on the bender, as you can see no stress/crack lines on the outside of the bend, however the bend has a slightly larger radius, not sure what others think but my explanation is that the material that was not annealed has started to fracture giving a tighter but probably weaker bend due to the stress/fracture lines, whereas the softer annealed material has actually bent.
I took a small piece of annealed aluminium and bent it back and forward just using my hands, just as it is with annealed copper I could feel it stiffening with each bend. I think from now on I'll be annealing any Al that needs to be bent
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