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Would re heat the alloy after beating make it less likely to crack? Can't be bothered now it's re sprayed...
It's only preventing the rack from pivoting backwards, most effort is in the legs so of be surprised if it ends up breaking... If it does, the rack comes with two struts so I'll have to start again...
Thanks for the tip!(Note: it looks red on the picture, but that's only the discoloration of the epoxy paint, the alloy didn't get that hot)
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My mistake - I thought you'd got close to a red heat!
If it hasn't cracked already, it should be ok - you'd see cracks starting as you beat the ends to shape, by which time it's probably too late. I was trying to add a bit more information to your idea if anyone else wants to try this - what you've done looks fine and I'm very much in favour of making things fit properly.
Re-heating at this stage will result in a 'softer' material - less likely to suffer brittle failure but more likely to distort under load. This might be a good thing (compliance / accommodation of variations in thickness / better alignment when bolted up) or not so good (elongated holes, bolts becoming loose) - very much a case of try it and see.
By heating it, you're annealing the metal - it will then work harden as you beat it to shape, and may need re-annealing part way through the process to reduce the possibility of cracks forming.
Many aluminium alloys melt before they reach red heat - old school / low tech metalworking would have you polish the surface and smear it with household (bar) soap before heating, and remove from the heat as soon as the soap turns black. Polish again before shaping - it's easier to clean if you haven't beaten burned soap into the surface...