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Posted: 5/27/2009 4:32:54 AM EDT
| Ok, so I had a build with a Vltor VIS that the barrel was not fitting so I did the ol' heat and cool process. Except, this time things did not fit together after 5 minutes at 250 in the oven, and after a long conversation with my father who is an engineer and designs and fabricates instruments with aluminum I was convinced to bake at 350 for around 7 minutes (he wanted longer). Things went together, but after thinking about it today, he works mostly with barstock aluminum, and most of his metullurgy knowledge is not with aluminum. I think I am ok, but what do you guys think? This is not my first build (7th), but its the first one with fitting issues. |
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7075 will not begin to anneal until 775F.
However, 250F would have been the correct choice for simply softening it. 350F is too high. T6 hardening is done by heating at 250F for 24 hours and then left to air cool. Annealing is done by heating to 775F for three hours and then lowering the temp 50F an hour until the temp is 500F then air cooled the rest of the way. You should be fine though since your time was fairly low at these temperatures that the gun will most likely see anyway. I would be more worried about the finish on the aluminum being damaged. |
| You're worried that you harmed your receiver by heating it to 350 degrees for 7 minutes? Lots and lots of people paint their receivers with Norrell's/Brownell's/GunKote's/DuraCoat's bake on finishes and then bake them at 300 - 350 degrees for an hour or two or three without any problems. |
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Quoted:
You're worried that you harmed your receiver by heating it to 350 degrees for 7 minutes? Lots and lots of people paint their receivers with Norrell's/Brownell's/GunKote's/DuraCoat's bake on finishes and then bake them at 300 - 350 degrees for an hour or two or three without any problems. thats true, I too have done a few frames with GunKote. I didn't think of that, but I was getting some flak on another forum and began to worry. I also tried it 2x at lower temps, 200 and 250. |
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