Some time ago I posted looking for info on resistance soldering. I was going to wind my own xmfrs. Because of time constraints I only got two of the three wound and couldn't get enough amperage. Then, I heard about the Harbor Freight 220 volt, made in America spot welders on sale for $149.95. I bought one of those and experimented. First, a steel welding table was used as one of the electrodes and heavy wire was run to the parts as the other electrode. The parts would not get hot. I think this is because the big steel welding table was heating up instead of the brass parts because the steel has a higher resistance. Next, I ran heavy wire from the spot welder electrodes to the brass parts. This worked. By turning the welder on and off the heat was controllable and solder flowed. Further, the brass did not become discolored like it would have if a torch was used. The parts soldered were only test pieces. Next week the real parts get soldered. Eric
resistance soldering 1/4 brass update
Sep 10, 2004
7 Replies
I probably don't know what I'm talking about, but I don't think I would turn the welder on and off *under load*. That's like switching currents while welding - also a no-no. Ken.
You don't know what you're talking about, Ken. :-)
A spot welder is normally switched hot. That's the way they work.
*However*, I'd caution Eric to mind the duty cycle limits of the spot welder. If I recall correctly, the HF spot welder has a duty cycle of only 1%. So don't leave that thing triggered for more than about 1 second at a time.Gary
Spot welders are designed to be switched under load. Switching is done on the primary side.
The 220 volt spot welder has a 50% duty cycle. Anyway, it didn't even get warm. ERS
My mistake, I was thinking of the *stud* welder they sell. Different animal.
Gary
Hello, I am curious as all get out. What are you making that you don't want to use a torch? I don't have any torch discoloration with brass soldering. Are you "silver soldering" (Brazing)?
LB
I'm not silver soldering but am using a silver bearing solder that has a fairly high melting point. It is being used because of the strength. Though the brass won't discolor like silver soldering there is some tarnishing that happens that is a little hard to polish out. These frames are made of 1/4" 2" x 2" brass angle. The main reason for the resistance soldering is to limit heating to a small area and avoid as much distortion as possible. The brass frames fit into a larger frame with only about .010" clearance. They are doors in a floor. They will each weigh about 100 lbs and are about 15" x 30". They will have marble set in to match the floor. Cosmetics are important. ERS
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