Alt-BEAM Archive

Message #04848



To: beam@sgiblab.sgi.com
From: Robert McIntosh robmc@acay.com.au
Date: Thu, 24 Jun 1999 22:01:42 +1000
Subject: [alt-beam] Re: glue for metals...



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Bruce Robinson wrote:

> "G.R.Reddy" wrote:
> >
> > I am having problems sticking two 1mm thick sheets of aluminum. I tried
> > araldite and other general purpose epoxy glues, but its not strong
> > enough. I would really appreciate if some one can suggest me some sure
> > shot glue to stick aluminium.
>
> Aluminum just doesn't seem to want to "stick", does it. Actually, it's
> possible to do all those things you "can't do" with aluminum -- solder
> it, weld it, glue it. The catch is, you need lots of special knowledge,
> skill, and experience. Even professional welders hate the stuff.
>
> As for gluing -- some epoxies work, although I'm not sure how they will
> stand up to vibration. The key points are:
>
> 1) VERY clean surface. Aluminum oxidizes quickly, and the oxides aren't
> visible. You need to clean it JUST before gluing.
> 2) The glue needs to get a bite -- dead smooth surfaces are a problem.
> 3) You need a THIN glue joint.
>
> Points 1 & 2 suggest you abrade the surface just before gluing. Points 2
> & 3 suggest the abrasions should be very fine -- NOT coarse sandpaper. I
> use really fine emery cloth. Point three is critical go all glues
> (except those specifically made to fill gaps). In other words, CLAMP the
> surfaces.
>
> I've also found that not all epoxies work as well with aluminum -- I
> haven't had much luck with 5 minute epoxies, or any of the ones sold in
> tubes -- they're too thick.
>
> Finally, the nature of the forces acting on your glue joint make a
> differences. Because aluminum alloys are often soft and ductile, you can
> sometimes get a "peeling apart" effect. I've found in most of my failed
> attempts to glue aluminum, it was the physical arrangement of the joint
> that was the real problem.
>
> I've had quite a bit of success with a combination of thin, liquid
> epoxies and one or two small pop-rivets. The rivets clamp the surfaces
> very tightly (making a thin joint), and stop the "peeling apart" forces.
> The glue provides added strength and prevents any loosening around the
> rivets.
>
> Good luck,
> Bruce

There is a solder for aluminium which can be used to weld it using a small
gas torch. http://www.farnell.com



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Bruce Robinson wrote:
"G.R.Reddy" wrote:

>

> I am having problems sticking two 1mm thick sheets of aluminum. I
tried

> araldite and other general purpose epoxy glues, but its not strong

> enough. I would really appreciate if some one can suggest me some
sure

> shot glue to stick aluminium.

Aluminum just doesn't seem to want to "stick", does it. Actually, it's

possible to do all those things you "can't do" with aluminum -- solder

it, weld it, glue it. The catch is, you need lots of special knowledge,

skill, and experience. Even professional welders hate the stuff.

As for gluing -- some epoxies work, although I'm not sure how they will

stand up to vibration. The key points are:

 1) VERY clean surface. Aluminum oxidizes quickly, and the oxides
aren't

    visible. You need to clean it JUST before gluing.

 2) The glue needs to get a bite -- dead smooth surfaces are a
problem.

 3) You need a THIN glue joint.

Points 1 & 2 suggest you abrade the surface just before gluing.
Points 2

& 3 suggest the abrasions should be very fine -- NOT coarse sandpaper.
I

use really fine emery cloth. Point three is critical go all glues

(except those specifically made to fill gaps). In other words, CLAMP
the

surfaces.

I've also found that not all epoxies work as well with aluminum -- I

haven't had much luck with 5 minute epoxies, or any of the ones sold
in

tubes -- they're too thick.

Finally, the nature of the forces acting on your glue joint make a

differences. Because aluminum alloys are often soft and ductile, you
can

sometimes get a "peeling apart" effect. I've found in most of my failed

attempts to glue aluminum, it was the physical arrangement of the joint

that was the real problem.

I've had quite a bit of success with a combination of thin, liquid

epoxies and one or two small pop-rivets. The rivets clamp the surfaces

very tightly (making a thin joint), and stop the "peeling apart" forces.

The glue provides added strength and prevents any loosening around
the

rivets.

Good luck,

Bruce




There is a solder for aluminium which can be used to weld
it using a small gas torch.  http://www.farnell.com">http://www.farnell.com">http://www.farnell.com

 






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4849 Thu, 24 Jun 1999 08:24:14 -0400 [alt-beam] Re: hello "Jesse Merritt" I just built a small 'bot with the capabilities that you mentioned. I just
used the touch sensors from Ian's site and a 556 monostable multivibrator to
control the motors (differential drive). When a sensor detects an object it
triggers 1/2 of the 556. The output pulse of the 556 is connected to the
motor drive H-bridge and reverses the motor OPPOSITE of the collision. The
556 was used instead of the 555 because I needed 2 timers.

All of the parts used are readily available at the Shack, except for the
base which was an old AOL Compact Disk. Works great.

I'll write more on this type of system if anyone is interested.

Jes


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