[bongobill]

Hi,

I'm trying to either build or buy a resistance welder to weld a small copper rod (0.03" diameter x 1" long) to a piece of brass sheet. The weld would be at the end of the copper rod.

My research suggests that a capacitivedischarge welder would be what I need.

If anyone has any idea on what power range I should be looking for?

I have seen these battery tab welders on ebay but I'm not sure they would be what I need. - Updated Hand Held Spot Welder Welding Machine Laptop Mobilephone Battery 220V | eBay

Any suggestions appreciated! =) Thank you.

[Al_The_Man]

Resistance welding generally refers to high current low voltage for Ferrous metal.
A capacitive discharge is similar but stores a high DC voltage in a capacitor bank for a stud welding etc. I have not seen it used with two dissimilar non-ferrous metals however.
I believe what you need for bonding copper to brass is either braze or silver solder and a small flame source.
Al.

[awerby]

I don't think that will work either. Drill the brass sheet to a press-fit for the rods and drive them in. If it needs more holding power, use silver solder.

Andrew Werby
Juxtamorph.com

[DonaldE]

it's an interesting question, i will try to find answer of your question then i will surely tell you.

[sajurcaju]

I just built a resistance soldering unit. I found a 56A, 5VAC transformer at a hamfest and combined it with a Variac. If you do this, measure the primary current with the output shorted to figure out what size Variac. In my case I'm using a sharpened carbon rod to apply the voltage to the work; I don't want the electrode to weld to the jewellery.

I suspect it would work fine to weld the size rod you describe, but haven't tried that. When I short the carbon electrode to a bolt head, it gives a nice carbon arc.
What would definitely work with one of these is to use silver solder. I agree with Andrew that you will have a much better joint if you drill a hole in the brass. I don't know about press fitting a 0.03" rod, that sounds a little problematic. Just doing a butt join seems weak.

Steve