Copper bar soldering problem

[ConKbot]

I was soldering copper spacers to a bussbar that was 3.5x50mm x 300mm-ish long, and ended up having to use two propane torches to get enough heat into it to melt tin/lead solder (standoffs would only be in compression, no need for something more structural) One just couldnt get enough heat into the bar to flow all the joints. On the end of the bar, the first torch would start to melt the solder, but it wouldnt wet out the joint. It wouldnt even begin to melt the solder in the middle of the bar. Once the two torches were on it, no problem. 

So yeah, copper bars can soak up and spread a ton of heat.