Slotting (milling) aluminum - the answer
 

A while back I posted some questions on the subject.
In general the responses to my and prior questions were
not too good - neither was my early experience.

The 6xxx aluminum is nearly impossible to slot, as it is soft &
gummy etc. However I continued the search for the right
alloy, as I have seen it done in Russia.

And finally here's the answer: use 7xxx (aircraft alloys) -
these slot just fine, down to 1/16" end-mills in 1/8" plates.
Done it myself, on HF mini-mill with great results.

Some links (no affiliation): world's greated hobbyist sto
mcmaster.com . Excellent source for miniature carbide end-mills:
http://www.discount-tools.com/bes-200.cfm

Bought from both many time, w/o slightest problem.

"Rashid Karimov" wrote in message
om...
snip-----

The 6xxx aluminum is nearly impossible to slot, as it is soft &
gummy etc.

Not if you specify a T6 condition. That machines quite well, but requires
adequate lubrication while machining.

And finally here's the answer: use 7xxx (aircraft alloys) -
these slot just fine, down to 1/16" end-mills in 1/8" plates.
Done it myself, on HF mini-mill with great results.

You'd also enjoy machining 2024 aluminum, but it, too, just like 7075 and
6061, should be in a heat treated condition. Any of the soft condition
aluminums don't machine nearly as well as the artificially aged materials
do. Seek a T351, T4, T6, or higher condition and you'll have good luck
with any of them.

Be advised that 6061 is the only material from this group that can be
welded, and if it is, it loses the aged condition. It can be restored after
a solution heat treat, than aging once again.

Harold.

Rashid Karimov wrote:
A while back I posted some questions on the subject.
In general the responses to my and prior questions were
not too good - neither was my early experience.

The 6xxx aluminum is nearly impossible to slot, as it is soft &
gummy etc. However I continued the search for the right
alloy, as I have seen it done in Russia.

I machine 6061 all the time, with no problem. I have even had
to anneal 6061 for bending, and then machine after the bend.
If you think you can plow a slot the width of the end mill
and leave it like that, it won't work. You have to mill the slot
right down the middle with a smaller end mill, then make
cleanup passes down both sides. The end mill wanders due to
the cutting forces, leaving a wavy wall. If the material is thick,
you need to mill it quickly in several passes of successively
greater depth until you break through, then do the cleanup
passes.

Jon

On Sat, 20 Nov 2004 01:25:20 -0600, Jon Elson
wrote:

Rashid Karimov wrote:
A while back I posted some questions on the subject.
In general the responses to my and prior questions were
not too good - neither was my early experience.

The 6xxx aluminum is nearly impossible to slot, as it is soft &
gummy etc. However I continued the search for the right
alloy, as I have seen it done in Russia.

I machine 6061 all the time, with no problem. I have even had
to anneal 6061 for bending, and then machine after the bend.
If you think you can plow a slot the width of the end mill
and leave it like that, it won't work. You have to mill the slot
right down the middle with a smaller end mill, then make
cleanup passes down both sides. The end mill wanders due to
the cutting forces, leaving a wavy wall. If the material is thick,
you need to mill it quickly in several passes of successively
greater depth until you break through, then do the cleanup
passes.

Jon
What works even better than running the endmill right down the center
is to bias it a little towards the climb cut side. The conventional
cut side of the slot is the side most likely to have the cutter dig in
and ruin the finish. This is because the cutter is being pushed away
from the climb cut side.
ERS

"Harold & Susan Vordos" wrote in message ...
"Rashid Karimov" wrote in message
om...
snip-----

The 6xxx aluminum is nearly impossible to slot, as it is soft &
gummy etc.

Not if you specify a T6 condition. That machines quite well, but requires
adequate lubrication while machining.


Tried that one too - to no avail. My application requires milling
hundreds of
slots (going metric for a sec): 50 to 12 mm longs, 6 to 2mm wide.
Doing it
in a single pass-per-slot is the best way to go.

Working with 7xxx allows plunge cut through 1/8 of material and then
moving the mill table to cut around perimiter. 2-flute endmills work
the best I found, 4fl get clogged up. I do use cutting oil.

Of course when using 1/16" end mill you can not crank up the feed
handle,
have to do it in .002-0.004 micro-steps. However with 1/8 endmill you
can
feed as fast as you can crank it




And finally here's the answer: use 7xxx (aircraft alloys) -
these slot just fine, down to 1/16" end-mills in 1/8" plates.
Done it myself, on HF mini-mill with great results.

You'd also enjoy machining 2024 aluminum, but it, too, just like 7075 and
6061, should be in a heat treated condition. Any of the soft condition
aluminums don't machine nearly as well as the artificially aged materials
do. Seek a T351, T4, T6, or higher condition and you'll have good luck
with any of them.

Be advised that 6061 is the only material from this group that can be
welded, and if it is, it loses the aged condition. It can be restored after
a solution heat treat, than aging once again.

Harold.

Huh?

6000 series Al slots just fine. You take about 0.005 inches vertical per pass.
You don't hog full depth.

The clearance on the end tooth is better than the side tooth, you see, so the
metal doesn't stick.


I tolerance everything and tolerate everyone.
I love: Dona, Jeff, Kim, Kimmie, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.
I fight terrorism by: Using less gasoline.

Actually if you just set it and run it expecting perfection full depth, what
happens is the cutter and work both deflect such that the climb side is tight
and the conventional side loose. This is caused by the more or less massive cut
forces right at center, and cutter rotation. The cut is deepest at center.

I know this because I mill on a cross vise with *no feed screws* frequently,
and have explored the feel of the cutter deflection both by opposing deflection
with my hand and by setting the gibs to lock with various friction settings.
For me this is true pleasure, and if I had a ball way cross vise with locks,
I'd be even happier exploring this relationship, looking for the stable path
between success and chaos.

It's like a freakin' tent revival. Pre-feedscrew milling technology. Ancient
knowledge.


I tolerance everything and tolerate everyone.
I love: Dona, Jeff, Kim, Kimmie, Mom, Neelix, Tasha, and Teri, alphabetically.
I drive: A double-step Thunderbolt with 657% range.
I fight terrorism by: Using less gasoline.

In article , Doug Goncz says...

It's like a freakin' tent revival. Pre-feedscrew milling technology. Ancient
knowledge.

Well there's still a motor driving the spindle. In *most*
cases. g

Jim


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Rashid Karimov wrote:

Working with 7xxx allows plunge cut through 1/8 of material and then
moving the mill table to cut around perimiter. 2-flute endmills work
the best I found, 4fl get clogged up. I do use cutting oil.

Which cutting oil? Try the citrus based stuff.

Ted