Your simplest solution would be to grind a moderate bevel on the loose
piece, get it welded to the extent possible, and then caulk the whole seam
with 5200. Don't go hi tech. - Bill
wrote in message
...
My outboard, 20hp Honda, jumped off my transom yesterday and hit the
pavement at 20-25mph. No critical damage but knocked a gapping hole,
the size of a golf ball, in the cast aluminum lower pan, the one below
the power head, next to the tiller handle. Fortunately, I have the
knocked out piece and it fits back in the hole perfectly. My first
thought was to have it tig welded. But it's in a really tight place
and I doubt I'd get a good weld without removing the pan which means
taking the whole power head off. I could tack weld it but that'd leave
a crack that could leak splashing water, not to mention look kinda bad
(as if it doesn't look bad enough).
So now I'm thinking about just using epoxy to glue it in. Mind you,
it doesn't need to be terribly strong. On the other hand, I don't want
it to fall out by just jostling either.
Anybody ever tried epoxy to glue cast aluminum parts back together?
How well will it hold? And for how long?
Thanks in advance,
Phantman

"Bill Kreamer" wrote:
Your simplest solution would be to grind a moderate bevel on the loose
piece

Actually, all the jagged edges match up perfectly and the piece fits
back together like a jig saw puzzle. Held in place, you can barely see
the seam where it fits together. I was thinking it'd be better to glue
it back just the way it is. Am I wrong for a reason I'm unaware?

get it welded to the extent possible, and then caulk the whole seam
with 5200.

In fact, I'd received that very advice at the coffee shop this
morning. Except in reverse order. Stick it together with 5200 (I was
told it's a Urethane based product) to bond and seal it, then
tack/spot weld it where possible for added strength.

Don't go hi tech

..... uh.... I dunno Bill, around here, 3M 5200 IS high tech lol!

Thanks :-)

PhantMan

On Wed, 12 Oct 2005 20:04:34 -0500, lid wrote:

My outboard, 20hp Honda, jumped off my transom yesterday and hit the
pavement at 20-25mph. No critical damage but knocked a gapping hole,
the size of a golf ball, in the cast aluminum lower pan, the one below
the power head, next to the tiller handle. Fortunately, I have the
knocked out piece and it fits back in the hole perfectly. My first
thought was to have it tig welded. But it's in a really tight place
and I doubt I'd get a good weld without removing the pan which means
taking the whole power head off. I could tack weld it but that'd leave
a crack that could leak splashing water, not to mention look kinda bad
(as if it doesn't look bad enough).
So now I'm thinking about just using epoxy to glue it in.

Check out JB Weld. The stuff is absolutely phenominal. I've heard of
people bonding pieces of engine block back on with it and running the
engine for years.

Corky Scott

--For grins you might post this problem over at
sci.engr.joining.welding Maybe you'll get lucky and have a hotshot from
that group within driving distance..

--
"Steamboat Ed" Haas : A greasy donut, a cup of
Hacking the Trailing Edge! : coffee and thou...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

steamer wrote:
For grins you might post this problem over at
sci.engr.joining.welding

My news server doesn't carry it. I put in a request for it though.
We'll see what happens.
Thanks. Didn't know it even existed.

West Systems 860 Aluminum Etch Kit
A two-part treatment for preparation of aluminum surfaces for bonding
with epoxy. Our research shows adhesion to aluminum is significantly
improved with this process. Also improves paint adhesion.
860-8 Two 1/4 pint bottles (treats about 50 sq. ft.)
860 Two 1-pint bottles (treats about 200 sq. ft.).

http://www.westsystem.com/

I didn't know aluminum oxidized within minutes so I did a test.

Part of a piece of aluminum was scraped removing any oxidation and making
the scraped part bright and shiny. Two hours later the scraped part was
still just as bright and shiny. Eighteen hours later the scraped part was
not as bright and shiny. Part of the surface which had been scraped the
day before was rescraped and the difference was noticeable, the newly
scraped surface was brighter than the surface scraped the day before, but
both scraped surfaces were still a lot brighter than the part of the
surface which had not been scraped at all.

I would conclude that there is some oxidation in the first 24 hours.



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On 15 Oct 2005 14:53:26 GMT, (William R.
Watt) wrote:


I didn't know aluminum oxidized within minutes so I did a test.

Part of a piece of aluminum was scraped removing any oxidation and making
the scraped part bright and shiny. Two hours later the scraped part was
still just as bright and shiny. Eighteen hours later the scraped part was
not as bright and shiny. Part of the surface which had been scraped the
day before was rescraped and the difference was noticeable, the newly
scraped surface was brighter than the surface scraped the day before, but
both scraped surfaces were still a lot brighter than the part of the
surface which had not been scraped at all.

I would conclude that there is some oxidation in the first 24 hours.


If you can't see the film, doesn't mean it's not there.
Astro mirrors are aluminized, these days.
In a vacuum chamber, a small aluminum sample is vaporized off a
filament onto the glass.
Then they let the air back in. That mirror surface looks good for
years. And if they hard coat it, it lasts even longer.

Brian W

William R. Watt wrote:
I didn't know aluminum oxidized within minutes so I did a test.

Part of a piece of aluminum was scraped removing any oxidation and making
the scraped part bright and shiny. Two hours later the scraped part was
still just as bright and shiny. Eighteen hours later the scraped part was
not as bright and shiny. Part of the surface which had been scraped the
day before was rescraped and the difference was noticeable, the newly
scraped surface was brighter than the surface scraped the day before, but
both scraped surfaces were still a lot brighter than the part of the
surface which had not been scraped at all.

I would conclude that there is some oxidation in the first 24 hours.



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William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
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THe thin layer of oxide that forms in the first seconds is nearly
transparent. Try again, this time using a white piece of cloth. Polish
until the area seems as "bright and shiny" as you want. Notice the
black stuff on the cloth. That is aluminum oxide. Wait 30 seconds and
use a clean portion of the rag to polish the "bright and shiny" part you
just polished. Notice the black stuff? That is more aluminum oxide.

Aluminum is like silver. It oxidizes almost instantaneously.

It is this thin layer that fails when gluing parts. The adhesive bonds
to the oxide layer and the oxide fails, not the glue.



--
“The darkest places in hell are reserved for those who maintain their
neutrality in times of moral crisis.”

dazed and confuzzed wrote:


Aluminum is like silver. It oxidizes almost instantaneously.

It is this thin layer that fails when gluing parts. The adhesive bonds
to the oxide layer and the oxide fails, not the glue.

I wonder how the Lotus Elise stays together then? It has an aluminium
tub-chassis, constructed from aluminium extrusions bonded together with
epoxy resin.

--

Geoff