Re: the power of junk, Is Parallel Programming Hard, And, If So, What Can You Do About It?

On 5/24/2025 4:07 PM, MitchAlsup1 wrote:

On Sat, 24 May 2025 17:32:05 +0000, BGB wrote:
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For a lot of the CNC stuff I am doing, aluminum is one of the most
common metals used (primarily 6061, sometimes 7075 and similar),
followed by carbon steel.

 Only about 325 grades of carbon steel...
 

Yeah, though most of the time, with carbon steel we don't have reason to care as much about which carbon steel it is.
Usually it is 1018 or A36 or something though...

Sometimes stainless steel, but stainless steel is both more expensive
and a pain to work with.

 Work hardens into non-machinable stuff with a single instantaneous
wrong move. Moral:: if you start machining 303 you must continue until
it is done. with no stopping, using plenty of oil/coolant, and sharp
tooling.
 

Usually 304, but yeah, basically that.
OK with flood coolant and carbide tools, which is mostly the current setup.
Usually works better IME with lower RPMs and more aggressive cuts, but then one is also more likely to snap off the endmills, so yeah.
Preferable to not deal with stainless steel...

>
Theoretically, one could melt and recast aluminum, but less likely to be
considered as "acceptable" (as the quality and metalurgy properties are
less likely to be the same as newly bought metal).

 6061T6 is artificially aged (hardened and tempered) which you will not
get
by remelting 6061T6 and casting it. At best you get 6061T0 which is more
like
1100 aluminum than 6061T6 and especially not 6061T6 (or 6061T155 cast
version
of the extruded version of T6 after artificial aging.)
 

Yeah, it is an issue.
If melt and recast, the properties change.
Not much first-hand experience working with recast aluminum though.
Would probably be an option if one just wants something for workholding devices or similar though; where the exact mechanical properties don't matter as much.

Say, if one goes and melts down the contents of their chip buckets (and
probably getting some ambiguous mixture of 6061 and 7075 and similar).

 Mixing 6061 with 7075 is not going to give you an aluminum that has
any of the properties you want. The alloying elements are different
and incompatible.

Yeah, but this is likely what one would get by just melting down the contents of a chip bucket. Maybe some amount of steel and similar as well, but this would probably just sink to the bottom. Probably also some zinc and whatever random other stuff has gone through the machine.
...