copper tube mod, aluminum cap. bad idea?

[Lance_Wallen]

I know different metals = bad news usually when acting as a conducting path, is it that big a deal though? I'm building a copper tube mod and was considering turning my own aluminum caps instead of using plumbing fixture caps on it. Would it be ok? would using some noalox resolve the issue if its not? Or should i just not do that

 

[altoids]

you know I saw somewhere they used an aluminum pipe that was threaded already then they found caps that fit on it to. how do you plan on matching those up screw on or wedge

 

[noc]

Might want to be careful with two relatively soft metals , so the threads dont gall. If your going to use aluminum end caps you might want to look at a aluminum called dural , one the strongest aluminum that is hardened with copper which will help with conductivity problem and the possible galling effect. Dural I think is the English version it might go by another name or just a grade here in the states.

 

[altoids]

Aluminum Pipe Fitting, Nipple, Schedule 40, 3/4" NPT Male X 4" Length
this is kinda off subject this is what I saw at amazon and told to buy and then find the screw caps to go on that are brass that might work for ya to and fits a big battery in it

 

[altoids]

GARDEN HOSE CAP 3 / 4 BRS
and these are the caps I was saying also on amazon

 

[Lance_Wallen]

I'm not threading the caps. they're going inside the tube body and being held with set screws.
I'll be turning the caps, or more accurately, plugs on my metal lathe. They'll be snug fit and held in with set screws. The body 'needs' to be copper because of part of my design. If copper on alum is just a bad idea when using the body as the ground path I could potentially make an aluminum body and put a copper sleeve on the outside but that makes it thicker than I'd like.

 

[altoids]

interesting so then the body will look all copper and top and bottom are silver looking no seams. I say whats the worst can happen a small fire or loss of power.

 

[altoids]

the only issue would the ground run through the body or a wire

 

[noc]

I dont think it will much matter , resistance would be nominal. But if you really want piece of mind you could do a copper bung and press it into the aluminum and have your set screw pass through the aluminum and tap into the copper making your connection for you.

 

[Lance_Wallen]

well, that's what testing is for I guess. Gonna make a prototype and send it around to a few people, will just see what happens after a month of heavy use.

now to the next delima, still tryin to find a good switch for the 14500 mod, so it has to fit in a 1/2inch tube O_O;;

Nothing I've found is rated for 3amp and the stuff that is rated for 3amp is too big for the tube. They barely fit in my 3/4inch tube.

 

[noc]

Or cut your copper bung a little on the loose side if a drill press isnt available and tin the entire piece in silver solder that will keep it from coming out and it will stick to the copper and not the aluminum . Making it pretty much bullet proof plus you wouldnt have to worry about oxidation

 

[Lance_Wallen]

the design has a copper body with the battery cap having a spring. I suppose I could line the alum plug with copper and make sure the set screw goes all the way through the aluminum cap to connect the copper bits. I'm probably just gonna do it alum on copper and see what happens

 

[asdaq]

You should see no electrical differences in mixing aluminum and copper. As the price of copper rises, it is quickly substituted with alu. The difference in resistance is small, and you aren't likely to notice this either. Chemically, the corrosion you get with alumina is salt based and provides a protective layer, and with patina it would eventually ' rust through', but they shouldn't interact badly with each other.

sent from my HTC genisis using Tapatalk

 

[locke2121]

Another aspect is the physical reaction two metals have with one another. Thread a steel bolt into an aluminum nut and leave it for a month...they actually bond together...the longer the tighter the bod. Sooner or later...its almost impossible to get them apart. But in this instance, i don't think copper and aluminum react that way with one another.

 

[noc]

Yes a dallop of antisieze or a graphite lubricant will save some heart ache. Even with no threads aluminum and ss love to stick to almost anything there in contact with .