Metal conductivity, at a glance

[duc916]

I pulled the data from here: Mechanical Charts - Relative Conductivity of Different Metals and graphed it.

Take from it what you will. There's the argument that brass and SS mods are more durable and corrosion/oxidation resistant, and that the large surface area and short length of distance that current has to travel minimizes any conductivity advantages of different metals. Still, the differences are more startling than I expected, and definitely makes me lean more toward copper mods these days.

 

[Norrin]

Nice find, copper is a pain though because it tarnishes so quickly. Would be interesting to know the values for SS although they won't be much different from normal steel am wondering if higher or lower

 

[Sgt.Rock]

The thing about those numbers though is how they translate into actual real life experiences with mech mods.

For example, that graph shows Copper at "100" and Brass at "25" (4 to 1 ratio) -- however that does not translate to 4 volts in a copper mod and 1 in a brass mod.

Actual testing showing voltage drop would be far more interesting.

JMHO...your opinion may vary

 

[KiLLeRr KeN]

Nice find, copper is a pain though because it tarnishes so quickly. Would be interesting to know the values for SS although they won't be much different from normal steel am wondering if higher or lower

If you want the copper to maintain is shinyness then as soon as you get it, put a couple of coats of clearcoat on it and it will shine for a while with no patina.. or you can patina it at first then apply clearcoat.

 

[MoonReef]

Its not a 4:1 ratio in volts but a 4:1 ratio in ohms

Just gonna do some quick math here

The resistivity of copper is 1.68×10^−8 Ω·m

Considering a mech mod thats 100mm long, 22mm OD and 20mm ID, which is pretty long and thin.

resistance = resistivity*length/area which works out to around 0.0000255Ω

That is negligible in a mech mod setup even with a resistivity thats 10 times of copper.

So it doesn't really matter if the tube is stainless steel or copper or brass.

Its all about the threads and the button.

 

[Papa Lazarou]

Here is something I did using data from Matweb for resistivity of some selected materials

My personal experience of mechanicals is that there is a detectable difference between using say an all copper mod and an all stainless steel mod. However, I don't have the same model of mod in both materials, so other things could be at play.. But I think in general there is a difference.

 

[Steamix]

zero point zero zero zero zero ...

...splitting hairs is coarse work compared to that.

A few stray electrons ...

Material itself don't matter much in that respect - they way it's put together very much so.
Shoddy craftsmanship, sloppy wiring. Best material won't do much if it's haphazardly cobbled together...

 

[duc916]

What about thermal conductivity as it relates to our mods? I notice my copper mods definitely pull heat away from my Orchid tanks much more efficiently. Not many people really care whether their juices are sitting in a hot bath, but I'm inclined to think the flavor would benefit from staying cool.

 

[Norrin]

If you want the copper to maintain is shinyness then as soon as you get it, put a couple of coats of clearcoat on it and it will shine for a while with no patina.. or you can patina it at first then apply clearcoat.

I was actually talking about the contacts rather than the outside, there is no way to stop the contacts degrading and with copper this is relatively quick. I would think the best mod would be copper with gold contacts. Yes I know silver is the best conductor but I think gold is the best conductor with the slowest oxidation. Could be wrong and don't think it is worth the extra expense.

 

[Sgt.Rock]

Now there's useful math MoonReef.

Thanks for the input.

 

[johndoe1027]

First of all, posting because a super useful thread wasn't automatically closed due to age... for once.

Secondly, I want to know more. A HUGE thanks to all that have posted and contributed to this thread. I have layman-level knowledge when it comes to conductivity. I have been an A/V installer for a decade now. I have always gravitated to copper mods as a result (since I can't afford silver). I assumed the mega-pricey gold mods conducted better... I feel sorry for anyone that bought one thinking the same.

I have bought copper mods (save a Sentinel) because they have to have less VD than SS. Part of my brain wonders though... how much difference can there be when the "conductor" is a big ol chunk of metal that's only a few inches long?

I know this example is 'apples to oranges' but stick with me. A couple years ago I put a subwoofer in my car. Not my first, maybe my 20th. I decided that, this time, the wire was NOT going to be the weak link. I used 0ga (yes, zero gauge) for the amp power wire (and vehicle grounds) and I used 8ga for the speaker wire from the amp to the sub (the wire that 'normal' people use to power the amp). Later on I did some more research and realized that 12ga speaker wire was more than ample at 10 FEET to carry the measly 1kW of power. Again, apple and oranges with the 1kW reference.

Where am I headed with all of that nonsense? I'm not 1000% sure at this point but if two small(ish) pieces of copper can carry enough current to do that job, TEN FEET AWAY, what about a chunk of stainless steel that will fit in the palm of my hand?

I need the help of someone with a SERIOUS voltmeter.

 

[NC Dripper]

Some good info in this thread. I've always wondered if it was worth buying a copper mod over SS for conductivity, but then having to deal with tarnish. I've spoken to people that swear there's a giant difference between SS and copper mechs and I've spoken to people that say as long as the contacts are copper based the tube material makes no difference.

 

[Munnin42]

I stayed away from copper for a long time because I have a serious allergy to it, but when my SS mod broke, my brother lent me a copper mod, and I have to say I am rather impressed by the difference in conductivity. I also have the bonus in that it doesn't seem to be triggering my allergy where I hold it in my hand

 

[Thrasher]

Some good info in this thread. I've always wondered if it was worth buying a copper mod over SS for conductivity, but then having to deal with tarnish. I've spoken to people that swear there's a giant difference between SS and copper mechs and I've spoken to people that say as long as the contacts are copper based the tube material makes no difference.

Like others has stated just an overall conductivity chart while useful is very lacking, something's like springs and spring materials, how much surface area inside the button actually makes contact with the surrounding channel, sloppy thread tolerances, size of pins etc.

One of the best metals to come alone for maintenance free contacts is rhodium. While slightly lower then silver it absolutely will not tarnish.

Another thing to do is to actually test the mod with a meter, after a few simple changes my brass nemi shows .01 ohms from pos post to neg threads when I press the button and a battery that gets pulled at 3.55 in my steel mod will last to around 3.36 in my nemi with the same Atty on it.

Same goes for an Atty many people check the coil build with a meter but then I will check from thread to pin as well (I don't trust the Atty meters)

 

[johndoe1027]

Like others has stated just an overall conductivity chart while useful is very lacking, something's like springs and spring materials, how much surface area inside the button actually makes contact with the surrounding channel, sloppy thread tolerances, size of pins etc.

One of the best metals to come alone for maintenance free contacts is rhodium. While slightly lower then silver it absolutely will not tarnish.

Another thing to do is to actually test the mod with a meter, after a few simple changes my brass nemi shows .01 ohms from pos post to neg threads when I press the button and a battery that gets pulled at 3.55 in my steel mod will last to around 3.36 in my nemi with the same Atty on it.

Same goes for an Atty many people check the coil build with a meter but then I will check from thread to pin as well (I don't trust the Atty meters)

My short time with a SS 4nine clone taught me the importance of surface area of the contacts, no matter the material. Never had a mod visibly arc on me before then.