Hi, I need to make some mitre cuts on thin sheet metal. Specifically the cornice pieces (like crown moulding) of thin gauge steel used for "tin" ceilings. I have a fine Freud Diablo blade that cuts wood beautifully smooth, but it mangled the cornice. So what do I need to set up my mitre saw to cut these? The cornices are thin gauge metal, and only around 4" wide. One time I had to cut some siding or something, and I recall needing to flip the blade to spin backwards or something. Not sure if that's the appropriate approach. Since these are joined pieces, the cuts need to be pretty exact. Thanks!