Chassis material

[Vlada]

Hi there guys, I am going to build jmp50 soon and I have a question about what chassis should I use. I have read a lot topics, but never found an answer. I think its personal preference, aluminium is easier for driling and steel is easier to bend etc etc. But there is one thing that bothers me most: can aluminium in contact with other metals corode overtime and cause shorts in ground path? I am asking about that because hey, we all use chassis as ground path.

[TIMBO]

Hey mate, As much as alli is good to work with, I think steel is better.
If you are custom making a chassis 1.2-1.6mm is good for heavy transformers.

I use Zinc Anneal, paints well.

[pompeiisneaks]

I've used aluminum and steel and hate working with steel.  Aluminum does need  you to drill holes and create a screwed connection to ensure a solid earth and ground connection, you can't solder to it like you can with steel, but those connections, if made and tightened enough, won't go bad over time. 

I do think it's just personal preference.

~Phil

[PRR]

Dry Aluminum hardly rusts.

Wet anything rusts/rots/molds.

The utility power system, from the dam generator to your cellar fusebox, is 99% Aluminum. Much of it in the rain or the damp ground, places you should not leave your amp.

Back when radios were MUCH more expensive than later, you would see copper-plated steel and even chrome over copper on steel. Copper-plate persisted in some military gear. If you are going to camp in a swamp for a year it may make sense. But not for a one-off.

> I think its personal preference

I think you DID find The Answer.

[Willabe]

I am asking about that because hey, we all use chassis as ground path.

Some guys don't, I don't, and some limit the chassis grounds. I only have 2 chassis grounds and 1 is for the 3rd power wire safety ground.

Here's link on grounding that explains 'wired grounds' that don't use the chassis for random grounding. 

http://www.valvewizard.co.uk/Grounding.html

[Vlada]

Wow, great answers. Thank you guys. I have three options for chassis:
1. Aluminium - I used on two last builds and had very good results
2. Steel - done only one amp on steel chassis for my friend(his father in law made it), also very good just a little harder material for drilling, but I used small drill press and was drilling slowly so that wasnt a big problem
3. Stainless steel - havent tried this one, and I think its a bad idea because the heat dissipation
I have never done Larrys grounding and thought about trying it in this amp, so I am that sceptycal about chassis as ground point. Anyway, I am sure that I am overthinking and should go with good old steel or aluminium

[Joel]

I used to have access to a variety of aircraft grade sheet metal and had a friend bend up some chassis for me.  Rated from best to worst;

1. Aluminium - easy to work with
2. Stainless Steel - difficult to work with
3. Titanium - impossible to work with

[shooter]

Titanium - impossible to work with

If you do build with T, I have a set of Titanium tools you can buy, IIRC the #2 Philips was ~$80 

[davidwpack]

Titanium chassis? Don't aliens use that for space ships and such?

[PRR]

Stainless steel is not a heat dissipation problem. The worst metal is 100X better than the air the heat goes to.

The problem with SS in the average workshop is that it (most grades) hardens in drilling/sawing, harder than even good drill-metal, and you don't get anywhere. Also it is hard from the start so will not bend as easy as most steels and aluminums. And VERY expensive.

FeC vs Al:

Steel is cheaper per ton. Once you have the tooling, you can make a million in steel cheaper than any other structural metal.

Aluminum is cheaper "per hole". You can bang it out with a wood-chisel, and do holes up to pot-size with an egg-beater. If you do a million, the power and bit-wear will be much lower than steel holes.

Steel corners can be welded at the auto-body shop. Aluminum is trickier. (It happens I was just wondering this now that Ford is making mostly-Aluminum trucks-- are the sharp body-shops doing Al weld now? Or just buying whole fenders?)