Eastwood sells some flexable copper thingies just for this. Here's a link to it.
<a href="http://www.eastwoodco.com/aspfiles/itemdy01.asp?UID=2002121215504245&T1=19108&Dep_Key1=WelDg" target="_blank">www.eastwoodco.com/aspfiles/itemdy01.asp?UID=2002121215504245&T1=19108&Dep_Key1=WelDg</a>
<a href="http://www.eastwoodco.com/aspfiles/itemdy01.asp?UID=2002121215504245&T1=19108&Dep_Key1=WelDg" target="_blank">www.eastwoodco.com/aspfiles/itemdy01.asp?UID=2002121215504245&T1=19108&Dep_Key1=WelDg</a>
