Weld Scripting Help?

I made a giant version of the gun I am making(for the details) and I named its surfaces to weld and it worked. I used a minimap script to shrink it down and when my character holds it it only holds the handle. The other parts are on the floor(so it can't weld). I renamed the part surfaces to weld but it still wouldn't work. I tried to find out how to weld script but the wiki confused me and so did looking at the free models. Anyone know any videos or something that will help me understand weld scripting better, like that shows you an example of how someone would build and weld script a model(like I said a link to a video would be the best answer)?