Setup to cut sheet metal

JHZR2

Staff member
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46,270
Location
New Jersey
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!
 
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36,515
Location
ME
Is there a way you can clamp the stuff between some 1/4" wood you can sacrifice in the process?
 
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258
Location
Western NY
What Trav said - try an abrasive blade. I cut aluminum Rondec-CT with one. It's kind of thick stuff, but the abrasive blade did a great job. You could also try a miter box and a hack saw, if that would work for the angles you need (and the job is small enough to make hand tools feasible).
 
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9,794
Location
Ontario, Canada
Backwards blade in the mitre saw works quite well with aluminum without mangling the profile, but probably not steel for fine work. Also I have no experience with tin ceilings, but instead of trying to make the perfect matching mitre cuts, maybe think about how you can hide one cut under the abutting piece, stuff like that might make the job look better with less aggravation.
 
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4,998
Location
Milwaukee, WI
An alternative to cutting miters would be coping. In short, run one piece all the way, then use a tin snips to cut the other to the profile. With wood trim coping is a little more forgiving in older homes (or any home) where the walls aren't perfectly straight. Recutting every miter two or three times because you can't get it tight because the walls aren't a perfect 90 degrees gets old. I assume this would also work with tin, though I've never done it.
 
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