6061-T6511 - Dimensional and Flatness Tolerance

I've bought 6061 T6511 from several vendors. Is there a spec I can look up for what what should be considered acceptable?
1. One consistently provides out of flat stock. Sometimes more than .015 across a piece of 1/2x6 flat bar. (ACROSS)
2. One has certain sizes that are from 0.003 to 0.050+ over size, but mixed. Some a little over. Some a lot over. I can't grab two bars and cut them to length and use them together even for rough work unless I also size them on all dimensions.
3. Another sent me some stock that is from .005 to .01 under size on all dimensions.
I mentioned the problem to number 1 and they said its within spec and sent me a spec number. That was a long time ago, and it was easier to just stop buying from them at the time. Other vendors did not provide stock in the same sizes warped to the same degree.
I also asked about the huge stock size variance from number 2, and they said I should just machine it to size. They are partially right, but I due a fair amount of work that doesn't need all six sides machined if the stock is nominally close to the same size. I didn't quit buying from, but I don't buy much from them due to price. Also instead of stocking or bringing in a requested size stock for me they want me to buy larger more expensive stock and just machine off and throw away the rest. "Bring in the right size stock? No just buy bigger and throw away 25% of it."
I have not said anything to number 3, but I recently tried to run some stock in a pre-made fixture plates and found myself having to add shims to my edge clamps to hold the stock. They are an order of magnitude better price than number 1 or 2 and have the best overall selection. All of the stock I have gotten from them has decent flatness. I still would like to continue buying stock from them on a regular basis, but I'd like to know what the spec is for 6061-T6511 acceptable dimensional accuracy before I say anything. O/+ seems like it would be acceptable, but (-) I would not think should be at all. Its shaving pennies off value to increase profits.
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"Bob La Londe" wrote in message
I've bought 6061 T6511 from several vendors. Is there a spec I can look up for what what should be considered acceptable? ------------------
Does this help? https://www.mkmetal.net/images/uploads/Alum%20Extrusion%20Standard%20Tolerance.pdf
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On 2/21/2021 1:25 PM, Jim Wilkins wrote:


It could. Thank you.
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On 2/21/21 1:11 PM, Bob La Londe wrote:











Just as one comparison point McMaster Carr shows a thickness tolerance of +/- 0.009" for 1/2" x 6" x length extruded 6061-T6511 in both sheets and bars. No mention of flatness, just "all other tolerances ASTM B221".
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Regards,
Carl

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On 2/21/2021 3:13 PM, Carl wrote:













I always forget McMaster Carr for stuff like that. They are a great information resource.
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