Aluminum materials related questions

[nondem]

I've started on my plane!!!!

I have a couple of questions that should be easy for you guys to
answer...

The first one is almost stupid but I'm anal about these things: What
grit of sand paper is ideal for sanding/deburring the cuts I've made in
6061-T6? The saw/blade I used really did a good job to the point that
it almost doesn't need sanding but like I said - I'm anal about this
stuff.

The second question is more technical: I'd planned to use 6061-T6 plate
in .125" thickness for my gussets. I've found a source for plate in the
same sizes but in 5052 w/no "-" number listed.
I looked up the numbers and 5052 appears to have very similar strength
to 6061. Can someone advise me if using 5052 is advisable and if I need
to look for a specific "-" number?
The 5052 is only slightly cheaper but much easier to find...I'm
interested in doing the job right.

BTW: Here is where I'm at on the build...

http://68.35.241.46/plane/index.htm

[John T[_1_]]

5052 is very soft compared to 6061. 5052 is often used for fuel tanks.

Stick to 6061, or whatever the designer specifies.

John

[Orval Fairbairn]

In article >, John T >
wrote:

> 5052 is very soft compared to 6061. 5052 is often used for fuel tanks.
>
> Stick to 6061, or whatever the designer specifies.
>
> John

Not only that -- but it is potentially fatal to use something in a
structural location if you don't know its temper.

[[email protected]]

nondem wrote:
> I've started on my plane!!!!
>
> I have a couple of questions that should be easy for you guys to
> answer...
>
> The first one is almost stupid but I'm anal about these things: What
> grit of sand paper is ideal for sanding/deburring the cuts I've made in
> 6061-T6? The saw/blade I used really did a good job to the point that
> it almost doesn't need sanding but like I said - I'm anal about this
> stuff.
>
> The second question is more technical: I'd planned to use 6061-T6 plate
> in .125" thickness for my gussets. I've found a source for plate in the
> same sizes but in 5052 w/no "-" number listed.
> I looked up the numbers and 5052 appears to have very similar strength
> to 6061. Can someone advise me if using 5052 is advisable and if I need
> to look for a specific "-" number?
> The 5052 is only slightly cheaper but much easier to find...I'm
> interested in doing the job right.
>

The *-* number is commmonly referred to as 'the temper', it tells
you how the material has been heat-treated. That is really important
as the strength depends on it. If you buy the material in the
annealed state, which is the softest state, you'll need to get it
hardened. That in turn, is non-trivial.

6061 has good corrosion resistance, I dunno about 5052. Electrolytic
Corrosion is always a consideration when mixing alloys.

Respectfully, you should be at least as anal about material choice
as about finishing the cut edges. Speaking of that, I suggest
you get a 'multipack' of sandpapers and work your way down
through the grits until the edge is shiny without visible scratches.
Then you can guage how much of what grits you'll need to buy.

> BTW: Here is where I'm at on the build...
>
> http://68.35.241.46/plane/index.htm

Looks good. Thanks for putting up your pages.

--

FF

[Jim Carriere]

nondem wrote:
> I've started on my plane!!!!
>
> I have a couple of questions that should be easy for you guys to
> answer...
>
> The first one is almost stupid but I'm anal about these things: What
> grit of sand paper is ideal for sanding/deburring the cuts I've made in
> 6061-T6? The saw/blade I used really did a good job to the point that
> it almost doesn't need sanding but like I said - I'm anal about this
> stuff.
>
> The second question is more technical: I'd planned to use 6061-T6 plate
> in .125" thickness for my gussets. I've found a source for plate in the
> same sizes but in 5052 w/no "-" number listed.
> I looked up the numbers and 5052 appears to have very similar strength
> to 6061. Can someone advise me if using 5052 is advisable and if I need
> to look for a specific "-" number?
> The 5052 is only slightly cheaper but much easier to find...I'm
> interested in doing the job right.

http://www.aircraftspruce.com/catalog/mepages/aluminfo.php

is a very good explanation.

5052 isn't considered heat treatable, that is mostly why there is a "-".
This also makes it a good choice of alloy for welding (it is popular
for fuel tanks). The heat from welding usually results in a heat
treatable alloy (such as 6061, for example) not being tempered anymore
(starts out as -T6 but becomes O after welding, for example).

I would use a file to clean up the edges and burrs. I wouldn't use
sandpaper because bits of the abrasive material may become embedded in
the workpiece and create a corrosion problem later on. For similar
reasons, I've been told not to use a pencil for marking aluminum
(measurements, notes), although a Sharpie pen is acceptable. Then
again, the designer may have taken these issues into account.

The other responses address the question of substituting one for the other.

Nice webpages :)

[Lou]

Really, you couldn't find any? Try these,
http://www.metalsdepot.com/products/alum2.phtml?page=sheet&LimAcc=$LimAcc&aident=

http://www.onlinemetals.com/merchant.cfm?pid=1246&step=4&showunits=inches

[[email protected]]

Jim Carriere wrote:
> nondem wrote:
> > ... What
> > grit of sand paper is ideal for sanding/deburring the cuts I've made in
> > 6061-T6? The saw/blade I used really did a good job to the point that
> > it almost doesn't need sanding but like I said - I'm anal about this
> > stuff.
> >
> >...
>
> I would use a file to clean up the edges and burrs. I wouldn't use
> sandpaper because bits of the abrasive material may become embedded in
> the workpiece and create a corrosion problem later on. For similar
> reasons, I've been told not to use a pencil for marking aluminum
> (measurements, notes), although a Sharpie pen is acceptable.

WIth pencils, the issue is the graphite. There is a similar problem
if steel wool is used on aluminum.

A lot of sandpapers use Aluminum Oxide (Alundum) grit. That is
the same oxide that forms naturally on aluminum so that should not
be a problem. But most of the wet/dry papers use silicon carbide,
(carborundum) which may be a problem.

--

FF

[cavelamb]

wrote:


>
> WIth pencils, the issue is the graphite. There is a similar problem
> if steel wool is used on aluminum.
>
> A lot of sandpapers use Aluminum Oxide (Alundum) grit. That is
> the same oxide that forms naturally on aluminum so that should not
> be a problem. But most of the wet/dry papers use silicon carbide,
> (carborundum) which may be a problem.
>

You don't sandpaper the edges - you file them...

The trick to good looking parts is finishing the edges.

Are they smooth, flat, free of nicks and scratches?

Sandpaper alone won't do that...

Richard

[Bob E.]

To deburr use a deburring tool which will take the sharp edge off the
inside of the tubing and the edges of sheet, finish with scotchbrite
pads. Use the 6061-T6.

Bob

[Peter Dohm]

> To deburr use a deburring tool which will take the sharp edge off the
> inside of the tubing and the edges of sheet, finish with scotchbrite
> pads. Use the 6061-T6.
>
> Bob
>
There is also a rotary version of the scotchbrite pad(s) that is really
slick.

Peter

[[email protected]]

cavelamb wrote:
> wrote:
>
>
> >
> > WIth pencils, the issue is the graphite. There is a similar problem
> > if steel wool is used on aluminum.
> >
> > A lot of sandpapers use Aluminum Oxide (Alundum) grit. That is
> > the same oxide that forms naturally on aluminum so that should not
> > be a problem. But most of the wet/dry papers use silicon carbide,
> > (carborundum) which may be a problem.
> >
>
> You don't sandpaper the edges - you file them...
>
> The trick to good looking parts is finishing the edges.
>
> Are they smooth, flat, free of nicks and scratches?
>
> Sandpaper alone won't do that...
>

I agree that file would be better. Consider 'draw filing', which
is done by holding the file like drawknife which reduces the
angle of attack of the teeth and produces a finer finish.
Do you load a file with soap or something to keep soft
metals like aluminum from sticking in the teeth?

Sandpaper on a rigid sanding block would work too. I
personally _hate_ sanding so would much rather use
files, scrapers, stones, or burnishing tools.

Would you ever use sandpaper to prepare Aluminum for
epoxy, or rely entirely on chemical pre-treatment?

--

FF

[Dan Horton]

>>Do you load a file with soap or something to keep soft
metals like aluminum from sticking in the teeth?>>

You could, but unless you want to work yorself to death, get a vixen
file, 10 or 12 inches long. Aluminum won't clog a vixen, and it
removes material quickly.

Dan

[john smith]

In article . com>,
"Dan Horton" > wrote:

> You could, but unless you want to work yorself to death, get a vixen

Whoa! Just a quick glance at that first line will get ones attention!
I go to read the next line...

> 10 or 12 inches long.

Makes ones heart bounce again.
Then I start to wonder if I missed a Hangar Queen thread?

Please think about carefully wording your sentences to reduce the risk
of heart attack to the speed readers.

[Jim Carriere]

wrote:
> Would you ever use sandpaper to prepare Aluminum for
> epoxy, or rely entirely on chemical pre-treatment?

3M Scotchbrite pads nicely scuff up the surface for bonding or
prime/paint. Maroon is finer than green, either works fine (just don't
go nuts with the green since it is coarser). You can find the green
just about anywhere, but I've only found the maroon (7447) in a few
stores or online.

Also, since you're basically putting tiny imperfections in the surface,
consider metal fatigue and the load on the workpiece when it is in
service. Better put, for example, when prepping a wing spar, it is
preferable to sand along the length (in the direction from wingtip to
wingtip, back and forth) rather than across/around it. Did I mention to
go light on the sanding pressure? You want to remove some oxides and
lightly scuff up the surface.

I find that after scuffing (on steel too) there is a very fine dust that
takes a few wipes to clean off. My favorite to clean this is denatured
alcohol on paper towel.

Oh... since I brought up steel, it initially takes some serious cleaning
up that is way beyond what I have the patience to do by hand.

[Ernest Christley]

Peter Dohm wrote:
>>To deburr use a deburring tool which will take the sharp edge off the
>>inside of the tubing and the edges of sheet, finish with scotchbrite
>>pads. Use the 6061-T6.
>>
>>Bob
>>
>
> There is also a rotary version of the scotchbrite pad(s) that is really
> slick.
>
> Peter
>
>

And of what use is slick sandpaper, my good man 8*)

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

[Anthony W]

john smith wrote:

>
> Makes ones heart bounce again.
> Then I start to wonder if I missed a Hangar Queen thread?
>
> Please think about carefully wording your sentences to reduce the risk
> of heart attack to the speed readers.


I dunno, a hanger queen sounds like something to be avoided. ;o)

Tony

[cavelamb]

Ernest Christley wrote:
> Peter Dohm wrote:
>
>>> To deburr use a deburring tool which will take the sharp edge off the
>>> inside of the tubing and the edges of sheet, finish with scotchbrite
>>> pads. Use the 6061-T6.
>>>
>>> Bob
>>>
>>
>> There is also a rotary version of the scotchbrite pad(s) that is really
>> slick.
>>
>> Peter
>>
>>
>
> And of what use is slick sandpaper, my good man 8*)
>

Polishing!

[Peter Dohm]

"cavelamb" > wrote in message
ink.net...
> Ernest Christley wrote:
> > Peter Dohm wrote:
> >
> >>> To deburr use a deburring tool which will take the sharp edge off the
> >>> inside of the tubing and the edges of sheet, finish with scotchbrite
> >>> pads. Use the 6061-T6.
> >>>
> >>> Bob
> >>>
> >>
> >> There is also a rotary version of the scotchbrite pad(s) that is really
> >> slick.
> >>
> >> Peter
> >>
> >>
> >
> > And of what use is slick sandpaper, my good man 8*)
> >
>
> Polishing!

A better answer that I had when I got back to the computer.

Scotchbrite will definitely polish aluminum.

[Peter Dohm]

"Peter Dohm" > wrote in message
...
>
> "cavelamb" > wrote in message
> ink.net...
> > Ernest Christley wrote:
> > > Peter Dohm wrote:
> > >
> > >>> To deburr use a deburring tool which will take the sharp edge off
the
> > >>> inside of the tubing and the edges of sheet, finish with scotchbrite
> > >>> pads. Use the 6061-T6.
> > >>>
> > >>> Bob
> > >>>
> > >>
> > >> There is also a rotary version of the scotchbrite pad(s) that is
really
> > >> slick.
> > >>
> > >> Peter
> > >>
> > >>
> > >
> > > And of what use is slick sandpaper, my good man 8*)
> > >
> >
> > Polishing!
>
> A better answer that I had when I got back to the computer.
>
> Scotchbrite will definitely polish aluminum.
>
>
>
Grrr! I used to have a little 4 line poem with 12 errors,
and a spelling checker wouldn't catch any of them!

I was trying to say that Rchard gave a better answer THAN mine.

Peter

[cavelamb]

Peter Dohm wrote:
> "Peter Dohm" > wrote in message
> ...
>
>>"cavelamb" > wrote in message
ink.net...
>>
>>>Ernest Christley wrote:
>>>
>>>>Peter Dohm wrote:
>>>>
>>>>
>>>>>>To deburr use a deburring tool which will take the sharp edge off
>
> the
>
>>>>>>inside of the tubing and the edges of sheet, finish with scotchbrite
>>>>>>pads. Use the 6061-T6.
>>>>>>
>>>>>>Bob
>>>>>>
>>>>>
>>>>>There is also a rotary version of the scotchbrite pad(s) that is
>
> really
>
>>>>>slick.
>>>>>
>>>>>Peter
>>>>>
>>>>>
>>>>
>>>>And of what use is slick sandpaper, my good man 8*)
>>>>
>>>
>>>Polishing!
>>
>>A better answer that I had when I got back to the computer.
>>
>>Scotchbrite will definitely polish aluminum.
>>
>>
>>
>
> Grrr! I used to have a little 4 line poem with 12 errors,
> and a spelling checker wouldn't catch any of them!
>
> I was trying to say that Rchard gave a better answer THAN mine.
>
> Peter
>
>

S'ok Peter.