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7075-T7351 Aluminum, Gummy? How to machine?

Joined
Apr 14, 2018
Location
Airstrip One, Oceania
6269 alloy ? i shall await it with open arms... when i see that hunk of metal cross my desk , it will be
a little bit of heaven......unless
Could have been 6262 T9 ...

Aluminium 6262: Properties, Fabrication and Applications

but it was also marked "micro chip" which must be someone's trademarked additive or process. Seriously, chips flew off like snowflakes. Machined just like mag except no squeaky feeling and no fire worries.

unless it was radioactve material from a nuclear disaster. did you have it tested for micro/nano sieverts ?
it only takes a particle to get in your body and stay there forever.
Hmm. You think that's the cause of that damn root canal ?

don't accept un-known metals from fucked-up places .
Alan Steel and Supply in ... Redwood City ? Cool place. There were two on the Oakland side, too ... Continental ? and another one. A good scrap yard is hard to find now.
 

Joe Gwinn

Stainless
Joined
Nov 22, 2009
Location
Boston, MA area
You can also check the electrical resistance of aluminum. When i worked at Mcdonnel-Douglas in Long Beach they would check incoming parts with a device that would check electrical resistance between two electrodes. There is enough difference in electrical resistance to tell whether the material is 6061,2024 or 7075.

Was that a two-probe measurement, or a four-probe measurement? For that kind of precision of resistivity measurement, I'd think that four-probe is needed.

The probes are in a line. The outer two provide a constant current flowing in the material under test. Voltage is measured between the inner two probes. Doing it this way allows one to see very small voltage differences in the material without being confused by the voltage drops at the current terminals.

 

tnmgcarbide

Diamond
Joined
Jul 6, 2004
Location
N. GA- 33.992N , -83.72W usa
i don't know what russian/chinese scrap-yard you refer... but here in GA there ainn't no "scrapyard" , where
you can just waltz in and buy some materials. they'll pay you .27 cents for beer/soda cans all day,
but refuse to sell a cnc plasma'd shell of drops right next to it. isn't that "anti-recycling)
 
Joined
Apr 14, 2018
Location
Airstrip One, Oceania
i don't know what russian/chinese scrap-yard you refer ... but here in GA there ainn't no "scrapyard" where you can just waltz in and buy some materials.
SF area, I think Alan is still there, have read comments about them here. The two in the East Bay I am not sure about.

But yeah, seems like all the good stuff has been squarshed because of concerns about this, concerns about that. "Freedom", ya know ?
 
Joined
Apr 14, 2018
Location
Airstrip One, Oceania
I think I'd be careful eating anything "jail-o" that Cosby's been around...
From what he said, he gave quaaludes to girls who asked for them. I've never heard of a woman who declined that offer.

Bill got fucked over. And so did Weinstein. Why would anyone hang out with that fat ugly pig ?

To get famous. So they got famous then they snivelled about the payment. Pffffft.
 
Joined
Apr 14, 2018
Location
Airstrip One, Oceania
Why would anyone hang out with that fat ugly pig ?.......

yeahh my mom and dad... they never got famous-a sore anus and a jaill-o poop mile
Your mom and dad went to events in see-through dresses with their stuff on full display, hanging off Harvey's arm, then complained he treated them as sex objects ? I musta missed that (thank god) :D
 

tnmgcarbide

Diamond
Joined
Jul 6, 2004
Location
N. GA- 33.992N , -83.72W usa
stop insulting my parents . it wasn't their fault. my uncle said it was just going to be a fishing trip...

and my dad never wore his see-through thong around the house......just in the back yard when nobody's looking. get it straight.
 

tnmgcarbide

Diamond
Joined
Jul 6, 2004
Location
N. GA- 33.992N , -83.72W usa
we ain't going to Aintry.

Arnold Ziffel was on green acres.

ned beatty will never lose that stigma .
judge reinhold will long be remembered for the scene in fast times.
he got busted in a fantasy about the girl who opens the door for a q-tip.

ned got raped in the appalachian mountains by a toothless cracker.
 

triumph406

Titanium
Joined
Sep 14, 2008
Location
ca


Was that a two-probe measurement, or a four-probe measurement? For that kind of precision of resistivity measurement, I'd think that four-probe is needed.

The probes are in a line. The outer two provide a constant current flowing in the material under test. Voltage is measured between the inner two probes. Doing it this way allows one to see very small voltage differences in the material without being confused by the voltage drops at the current terminals.


I can't remember how many probes there were, this was back in the early 90's. I do remember the inspector being very carefull to calibrate the meter with the calibration coupons before testing parts.
It might have had only 2 probes, as a lot of parts they had to check were contoured with no flat surface for 4 probes to contact simaltaneously.

I was a contractor at McD, and the company i worked for were making parts for the Wind Tunnel shop at McD. One day I get called down and shown a part they had made, the inspector said it was supposed to be made from 7075, but the electrical conductivity showed it to be 6061 (there was only 7075 and 6061 at the shop so it was an either/or situation)

Turned out a part got scrapped out on night shift, they'd substituted the material that should have been 7075 with a piece of 6061. and being night shift did tell anybody what they had done. After that debacle every time new parts came in I'd get called down to the inspection lab so they could do an incoming inspection with me there. They were always hoping to find another part that had the wrong material. Luckily it never happened again.
 

triumph406

Titanium
Joined
Sep 14, 2008
Location
ca
mr. Engineer, no one is guessing these alloys based on density, that is about the worst option of them all

MIL-HNDBK-5 lists the density of 7075 (and 2024) at .101#/cuin, and 6061 at .098#/cuin, so a 3% difference. In other words somebody able to measure accurately, and using an accurate scale could discern the difference. Not what I would do, but it could be done.
 

PeteM

Diamond
Joined
Jan 15, 2002
Location
West Coast, USA
SF area, I think Alan is still there, have read comments about them here. The two in the East Bay I am not sure about.

But yeah, seems like all the good stuff has been squarshed because of concerns about this, concerns about that. "Freedom", ya know ?


They were in the process of closing last time I was there. Sims Metal is still around.

The Bay Area used to have dozens of surplus-anything places, particularly high tech detritus as well as some low tech stuff (e.g. Triangle Machinery). One of the last places, Excess Solutions, apparently closed its doors last year - maybe online sales remain. Mostly victims of rising land prices. I keep imagining they can't get any higher . . .
 








 
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