Case welding fail

[Zap]

Instead of doing another case mod, I decided to make a case out of scratch! Well, it didn't quite work out as planned.

First, I started with some raw materials, mainly some aluminum diamond plate, aluminum strap and aluminum angle. I don't have it all in the picture, but I have 32 square feet of diamond plate in two different thicknesses, and probably 30 linear feet of various size aluminum strap/angle.

After a few cuts, I used clamps to mock up a portion of the case. The diamond plate has a film over it (in case it looks funny). The case would have been 13"x13"x5.5" or so and would have held my mini ITX gaming rig (currently a pile of parts).

I could have riveted it together but since I purchased the gear already, I decided to braze it together. Brazing is kind of a low temperature welding method between true welding and soldering in temperature and strength. The rod is "Alumiweld" but similar stuff is sold under various trade names. Basically they are an aluminum alloy that melts a couple hundred degrees below the melting temperature of aluminum. The theory is that you heat up the aluminum with a cheap propane torch (like you would use for soldering pipes) and it becomes hot enough to melt the brazing rod, but not melt the aluminum. So, I peeled off the protective sheet from the diamond plate, beveled some edges and scuffed surfaces with a stainless steel brush (supposedly helps temporarily remove oxidation allowing for easier brazing). Then, I clamped the pieces together...

It didn't turn out like I had hoped. First thing was that initially I didn't heat the metal enough so while the brazing held to the aluminum angle, it did not bond with the diamond plate because the bigger piece didn't get hot enough. This is evident mostly to the left in the following three pics. I tried again, this time heating up the diamond plate more, and ended up with a nice smooth bead that bonded well on both sides, mostly evident in the center section.

UNFORTUNATELY the pieces warped, probably from the heat. First picture shows a smaller piece of aluminum angle held up against it. Second picture shows it sitting on a flat countertop. The aluminum angle actually warped! The diamond plate sorta pulls away from the aluminum angle towards the ends as if it were trying to stay flat. Heh, I used the aluminum angle because it is supposed to be rigid.

Well, I guess I'll stick to riveting pieces together until I can figure out how to do this without warping stuff.

I guess I won't be using my new rig at the next few LAN parties.

Anyone have any tips on brazing?

Oh yeah, I also tried doing some bends using a rigged up bending brake, but alas 0.060" plate is tough to bend without the proper tools.

 

[Hyperlite]

Maybe try a hotter gas? Like mapp gas? Might give you a bit more finite control over the situation.

Yeah, the diamond plate is going to be hard to bend...maybe if you have a benchtop vice, you can stick in in there with a couple 2x4s and bend along that edge?

 

[Rubycon]

You need to practice welding aluminum on some scraps. It's nowhere near as easy as brazing copper and welding steel by far!

A propane torch is a poor choice. An acetylene turbo torch with medium tip would be better. Best is a Henrob Dillon if you go oxyacetylene route. Still need lots of practice as control of heat is essential for proper fillet and damage control! Aluminum is an excellent conductor so you need LOTS of heat FAST but you have to be careful not to get any area too hot or the workpiece is ruined.

Alternatively a shop with a TIG welder can do this for you at a reasonable cost.

 

[v8envy]

One more vote for an IG welder. MIG with 100% argon is the way to fly. It's the only way to do aluminum, IMO -- aluminum oxidizes way too fast for oxyacetalyne. TIG sounds like it'd be great too.

My last try was using a thicker diamond plate to make a bumpers for my mini monster truck back in the 90s. Even with much thicker metal I had a hell of a time until I got some MIG welding tips from some pros.

Hmm. Wife's jeep could use some diamond plate bodywork for that all important Mad Max attitude. Time to rent a MIG welder.

 

[Tattare]

Mig spool gun is nice and quick but it leaves pits and dosnt look the best.
Tig you can get amazing looking welds but your looking at alot of money to get setup.

If it was me id go with a metal epoxy by 3m or devcon and some aluminum angle. Id use that for making the tabs instead of bending the treadplate and epoxy everything together.
Rivets will work but such a pain drilling all those holes and riviting them together.

 

[Fallen Kell]

When I first started reading I thought the original poster knew a little of what s/he was getting into when dealing with aluminium... It is quite frankly one of the hardest metals to try and weld together without making it look like crap. It's melt point is so low and its heat conduction co-efficient so good that it is really a nightmare situation without months of practice.

 

[Zap]

Rivets will work but such a pain drilling all those holes and riviting them together.

Rivets might work for me though, because I'm familiar with using them.

When I first started reading I thought the original poster knew a little of what s/he was getting into when dealing with aluminium...

Heh, so you thought...

Well, I did have some idea of the pitfalls, but I didn't think that the aluminum angle would warp as much as it did, plus it was my first time working with aluminum in this way.

I've done metal work in the past, but it was with mild steel (MIG, arc & oxy/acetylene).