How are the pipes soldered? just flat against the top, or do they insert into the holes? It looks like they are just flat against it...
I wouldnt imagine that being very strong (but im very tempted to do it on my blocks as it would save a LOT of effort
What solder do you use? standard 60/40 or lead-free solder? I could use either 60/40 or 95 Sn 4 Ag 0.5 Cu solder.. dunno which is stronger...?