Oh oh oh! I am kind of skimming here so not sure what metallic thread you are using but I just recently posted about a project where I used for the first time myself! I bought Gutermann's metallic thread a few weeks ago when it was half off at Jo Ann's...I used a size 12 Schmetz metallica needle and 40 wt. cotton in a similar color in the bobbin. It worked REALLY well - I only had one break, and it was at the beginning of the spool so I kind of wondered if that part of the thread was weak...after that no issues. I did test it on a little test sandwich first to get the tension right, but that's all. Good luck!!!