Will it mill? (or material Mystery)

I have recently inherited a block of aluminum from my father in law (no need for condolences, he is downsizing). He has carted this beast around for something like 50 years. It is pristine except for an attempt by his brother to cut a corner off it for a door stop. (This was the start or a years long feud).

It reads “9772 T6” on the end of it. It weighs about 150+ pounds and its at least 3 inches thick, ~3 feet by 2 feet. I am hoping that the T6 is a positive thing. I can’t find any reference to a 9772 type of aluminum anywhere. No idea where he got it, what it is worth or what I might even ever do with it. I may have to finish the job on the corner and see if I can cut it.

Anybody have any ideas what I am working with here or what I can do to figure it out?


:thinking: If you can get an accurate weight measurement then you could look for materials with a similar mass.
As an example, how much does a similar size block of 6061 weigh?

Might help narrow down the search.

I’ll have to also get an accurate measurement of volume for it too. It is a beast to move around. Maybe send a chip out for analysis? I am going to cut that corner off and see if I can work it.

If you cut a piece you can use a pipette of water to do a water displacement measurement for the volume and then weigh it?

Unfortunately the 9xxx series of Aluminium seems to be “other stuff”

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Well, that isn’t necessarily good news, now is it? :frowning_face: It least it was free.

I think I will slice that corner off and see if I can sacrifice a couple of end mills on it.

I am not hopeful based on the reference you were pointing me to. Maybe it turns out to be the most machinable alloy ever.

Everything is machinable if you use a hard enough cutter :wink:

But seriously, you can probably machine it OK, an air blast and a bit of lubricant might be needed if it’s gummy and sticky but carbide is harder than Aluminium. Go carefully with the depth of cut and see if it makes happy or unhappy sounds, pause frequently to start with to see if the material is gumming up the cutter and if it is add some lubricant or use a coated cutter (nothing with Al in the coating name though).


This is great advice. Thank you. I’ll get a piece off and see if I can do something with it. I am looking forward to the challenge.

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