Aluminum Alloy and thickness?

[pure_rock_fury]

I have been itching to get this project underway. I am still in the planning phase right now. Waiting on my press brake to get here and a few other tools and supplies. I am going to be building a case from square one. I guess my first question is what alloy should I go with for aluminum? I have done a bit of reading and it seems the most commonly available is 3003 and 5052. From the reading I have done, which was little, it seems that the 3003 forms a little easier while the 5052 is a little stiffer. I guess my question here is the difference enough to really matter in this kind of application?

Lastly I have noticed that Tribaloverkill, for instance, is using 0.125". How heavy is this stuff? I am going aluminum for two reasons... First is it's lighter weight, second is it's relative malability compared to steel. I have a small sheet of steel right now and that stuff is a huge hassle. I don't have any experience in metal work and am in a bit over my head here. Is .125" going to be too thick to be easily managed with out specialty tools considering the sheer amount of raw fabrication that I am going to have to be doing? I will probably end up mixing the thicknesses for internal/external parts and such, but I was curious what the more experienced thought of all this.

Thanks for your help everyone.

[Slug Toy]

ok, my first reaction is HOLY #$!?... .125" is equivalent to about 3 millimeters, which is very thick for sheet metal. my last check for pricing got me about $200 for a 4'x8' bit of 2 millimeter thick aluminum. ill bet you 3 millimeters will be half that again for a sheet.

i really dont think you need sheet metal that is so thick. at most i would say one millimeter, or .04" thickness is good for a case. if you do some smart shaping, you could even get away with thinner stuff.. but you need complex shapes that are probably out of your league since you said you have no experience.

in terms of 3003 versus 5052, that shouldnt really concern you. if you plan on using your case as a chair as well, or a ladder, then you would want 5052. for normal purposes though, 3003 will serve well. i dont see how you could be putting a vertical load on the case that is high enough to warrant extra structural strength. what you should worry about is cost.

in terms of weight, aluminum isnt bad at all. ive got some 3" width, .25" thick aluminum bars sitting around, and id say ten feet of that stuff may weigh about 8 pounds at most. for .125" or even .04" sheet metal, weight will not be a concern unless your case is the size of your house.

ill sum up here. go for .04" (1mm) thick aluminum or .08" (2mm) if you want to go overboard. use 3003 because strength shouldnt be an issue and it may be cheaper. dont worry about weight.

now go find some pricing and let me know. im always curious about that stuff.

[Aero]

hmm, I didn't know there were different alloys to choose from. I usualy just go with the scraps I can get from cases/junkyard/side of the road. :p

[pure_rock_fury]

I knew that there were different alloys, but I never really knew what the difference was until yesterday when I was researching prices online. I was seeing all these different numbers and didn't know what they meant. Basically the first number in the series is the "other" metal the is mixed in with the alum. 3003 has magnesium while 5052 has manganese. Exactly what this means and what it does to change the alloy I couldn't tell you. But the alloy number directly corresponds to what other metals are mixed in with the alum.

Not that it has a huge deal to do with the topic, just thought you may be curious. I think I am going to take your approach though. I called a few scrap yards around and will probably be checking them out soon to see what they have. After pricing this stuff out online, it would deffinately be nice to find some scrap in decent shape and size.

Thanks also to Slug Toy for the insight on thickness. There are a few pieces I would like heavy duty, but you are probably right that 0.125 is a bit more then necessary. Thanks again.

[Slug Toy]

so you dont know what the difference between magnesium and manganese is eh? well just for the sake of knowledge, ill tell you. the big difference is that magnesium is soft, manganese is pretty damn hard and durable.

if you've ever seen one of those big crushing wheels with the teeth on them, those are whats called manganese "hammer". i dont know why they're called hammers, but all you need to know is they are metal teeth and they are manganese because it lasts longer. manganese is also relatively weather resistant too. aluminum and magnesium and iron all oxidize, but manganese has a tendency to resist oxidation. so alloying with mangnese makes metals harder, last longer, and more weather resistant. id hazard a guess that manganese alloys would be more expensive as well seeming as they come with their various advantages.

the magnesium alloying usually makes metals more workable. magnesium is softer than aluminum, though not by much. ive also heard that magnesium alloys also hold a polished finish better, and that may be true because sterling silver has magnesium as a (relatively) large alloy in it and sterling silver definitely shines up better than regular silver.

as far as scavenging goes, thats a good way to save a lot of money. i personally wouldnt go to scrap yards because i like to know that what im getting is new and hasnt been sitting around for months outside. granted, you probably will find some good pieces that are either pretty cheap or free, but like i said, i like working with new stuff.

heres one hint ive picked up from experience with various metals. every metal has its own distinct smell believe it or not. aluminum actually smells kind of like a cross between a beach and sulfur. good aluminum shouldnt smell like that until you start working with it. bad aluminum will smell like that all the time. so if it smells odd as soon as you pick it up, its been sitting way to long and has had a chance to really stagnate.

if you want to know what other metals should smell like, just ask.

now go find some aluminum.

[crazybillybob]

The 3003 Is very soft. In fact that softness makes it had to work with. It gums up cutoff wheels and saw blades. I've used 2 types of Aluminum on R2 6061 and 3003....I will not be using the 3003 again. I really like working with the 6061 It cuts nice and shapes easy (I used .25" and .125" on R2). If your going to to do smooth bends the 3003 would be a good choice for the bent section but keep it's use to a minimum, as it sucks to work with. The 5051 is usale more expensive then 6061 and harder so it's a little tougher to work.


You can get sheets of all three type at a desent price. There's a metal shop close to where I work and I pick up "Scrap" or mistakes they have a big section of it in the front of the store with prices on each peice. Check out their website for regular prices but to save some cash give them a call they will ship the odds and ends that they sell too. Here's a link to their website www.asapsource.com (http://www.asapsource.com/public/index.asp)

They Sell Plex in all sizes and colors too.

Good luck,
Crazybillybob

[pure_rock_fury]

Thanks for the info guys.
Billybob, I actually was checking that site out and will deffinately give them a call about scrap / mistakes if I can't find anything local. Thanks also on the tip about the 3003. I plan on making rounded edges Lian Li style. Maybe I can use the 3003 for the front and top skins and the 6061 for the structural frame and internals.
Thanks alot guys, my knowledge on aluminum has increased 100 fold already lol. Boy this is gonna be a touch and go project, but you never learn until you get in there and F%^& it up a few times :D