Author Topic: Does solder provide mechanical strength? (Read 4368 times)

Charlie1138 · « **on:** March 08, 2008, 11:55:18 PM »

I am making a small rectangular metal box with some scrap metal -- some sheet metal from an old computer case and some aluminum angle iron...

I want to join this scrap metal into a box and am wondering if I could use solder to to join it. because it's so small screws are kinf of problematic and get in the way.

The thing is that I am trying to do this in a samll apartment so brazing seesm kind of extreme to try in here.. I am wondering if I could just solder the edges to hold it together. It's not a structural component.. I really just need it to be held together and keep light out because there will be a camera sensor in there.

If you don't heat all the metal of the box will the solder form a structural bond? So can you spot weld with solder?

Maybe some superglue would be enough for this project? Does anyone know of a glue that will bond metal reliably?

I just read the section on bonding materials on this site and
"steel cement" is mentioned.. but when I do a google search for steel cement I can't find anything.. are they refering to "Goop"?

ed1380 · « **Reply #1 on:** March 09, 2008, 12:27:35 AM »

I've brazed with solder. does that count? it was a pretty strong bond. it was a steel cable to a connector

Charlie1138 · « **Reply #2 on:** March 09, 2008, 12:47:01 AM »

Thanks for the response, ed.

Did you have to heat all the metal involved or did you just melt the solder to join them like wlelding?

Soldering is like welding with material that melts easily right? But brazing involves heating all the material to be joined rather than the mateiral to join them right?

Maybe you could just tell me the equipment and process you used and I could try that?

dunk · « **Reply #3 on:** March 09, 2008, 07:29:15 AM »

Quote

Soldering is like welding with material that melts easily right? But brazing involves heating all the material to be joined rather than the material to join them right?

nope.
welding is for joining 2 pieces of the same king of metal. the filler must also be of the same metal type.
brazing uses a different metal type as the filler and works between differing metal types.
by this definition soldering is a kind of brazing. you are joining a component lead (typically soft steel) to a PCB track (typically copper) using lead solder as a filler metal.

aluminium is a difficult material to glue or paint because an oxide layer forms on the outside surface as soon as it is cut. this oxide layer does not allow paint or glues to stick very well.
i think i read somewhere brazing aluminium doesn't work for the same reason but i can't remember for sure.

dunk.

Charlie1138 · « **Reply #4 on:** March 09, 2008, 07:49:29 AM »

That's a bummer..

Thanks for the inofo theough

I guess I'll have to try to use some little screws then.

Trumpkin · « **Reply #5 on:** March 09, 2008, 07:50:30 AM »

check out the brazing tutorial.

Charlie1138 · « **Reply #6 on:** March 09, 2008, 08:13:18 AM »

I was looking at the brazing tutorial.. but I feel like that is too extreme to try in an apartment. Do you think so? Or is it no worse that soldering?

I just dont' have anywhere to work.. maybe I could try it outside.. but that seems problematic, too.

ScorpIon · « **Reply #7 on:** March 09, 2008, 08:14:18 AM »

Do you have a balcony? Or could you like... have stuff on a board you stick out the window? xD

Charlie1138 · « **Reply #8 on:** March 09, 2008, 08:57:30 AM »

I could try the balconey.. does that seem feasible to anyone who has done it?

kd5kfl · « **Reply #9 on:** March 09, 2008, 10:40:50 AM »

Pop rivets

paulstreats · « **Reply #10 on:** March 09, 2008, 10:47:55 AM »

You can do spot soldering. Plumbers use 60w soldering irons and plumbers solder to spot solder pipe joints and sometimes temporarily repair burst pipes, There is plumbers solder available which provides a stronger mechanical joint but needs heating up more hence the 60w iron

Charlie1138 · « **Reply #11 on:** March 09, 2008, 01:01:32 PM »

Lots of great alternatives, thanks everyone! The pop rivets and plumber's solder sound like they could work well, I will start researching those.

Trumpkin · « **Reply #12 on:** March 09, 2008, 06:30:44 PM »

yeah definently don't do brazing in your apartment. Solder doesn't stick well to certain metals

bukowski · « **Reply #13 on:** March 10, 2008, 11:23:53 AM »

http://www.societyofrobots.com/robotforum/index.php?topic=2876.msg20646#msg20646

Soeren · « **Reply #14 on:** March 10, 2008, 02:53:24 PM »

Hi,

Aluminum can be soldered quite easily, it just takes the right solder (and that might be a bit hard to get for a hobbyist).
It can also be glued reliably with eg. supper glue or epoxy - as long as the areas to be bonded is CLEAN (the oxide doesn't prevent gluing).
It can be welded as well.

That said, I'd like to second the poster suggesting pop-rivets (or just use plain old rivets), if screws are a no-no. Personally I'd go with the kind of self tapping screws made for thin plate - they don't have to be much longer thanthe material to be joined.

Charlie1138 · « **Reply #15 on:** March 10, 2008, 09:07:43 PM »

Thanks for the information Bukowski and Soeren. Decisions decisions! heh

I think I might try the epoxy/super glue first then if that isn't strong enough I will try something else. Does anyone have a brand they would recommend.

ed1380 · « **Reply #16 on:** March 10, 2008, 09:34:14 PM »

jbweld? never used it on aluminum, but their website says it'll work. but it looks like the marine version is better for alum.

Charlie1138 · « **Reply #17 on:** March 10, 2008, 11:23:55 PM »

Thanks so much, ed. The "weld" part sounds very promising. That's good marketing.

bukowski · « **Reply #18 on:** March 14, 2008, 01:05:58 PM »

Wow, that's some neat stuff.

Tensile Strength: 3960
Adhesion: 1800
Flex Strength: 7320
Tensile Lap Shear: 1040
Shrinkage: 0.0%
Resistant to: 500° F

Gonna have to keep that in mind.

ed1380 · « **Reply #19 on:** March 14, 2008, 01:42:49 PM »

Quote from: bukowski on March 14, 2008, 01:05:58 PM

Wow, that's some neat stuff.

Tensile Strength: 3960
Adhesion: 1800
Flex Strength: 7320
Tensile Lap Shear: 1040
Shrinkage: 0.0%
Resistant to: 500° F

Gonna have to keep that in mind.

is that solder or jbweld? also what units are they measuring in?

bukowski · « **Reply #20 on:** March 14, 2008, 02:03:46 PM »

jbweld.
Tensile Strength is KSI, Im guessing Flex Strength and Shear are the same.
Adhesion I have no idea... dont know that much about adhesives.

superchiku · « **Reply #21 on:** March 15, 2008, 04:48:44 AM »

solders may not be dependable go with welding or just screwing them up better and more reliable

lkik · « **Reply #22 on:** March 29, 2008, 06:06:26 AM »

why dont you get a bit of metal that has a 90degree angle in it an just bolt it on
alot simpler

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Author Topic: Does solder provide mechanical strength? (Read 4368 times)

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