F***ing powersuply

I tried to spot weld the heatingcoil with four different powersuply's, the first one gave the best result: at 10 amp (max current) the wire welded together but they didn't fuse as much as I wanted.
Another powersuply (22 Amp) had a shortcut saffety so no current at all. With the third I was able to set the current, but when I switched it on it started smoking, without any load connected. Some internal shortcircuit or something, the suply probably hasn't been used for a couple of years so no one knows...
The last attempt was a self build suply. I found an old transformer (240 V -55 V) with coils made of thick wires. This one should be able to give me the current I need. A variac on the primairy coil should give me the ability to regulate the welding current. Unfortunately I blew the fuse...

So, I tried soldering with silver. It was tricky not to overheat the wire with the gastorch but I managed. Unfortunatley this connection broke after some fiddeling.
In other words: I walked a lot of kilometers today to get all the stuff together for nothing. Good thing the sun is shining!