I use a ten tooth per inch blade ( not a skip tooth)on really hard wood, brass ( I’ve cut trade gun buttplates out of old brass 7/16th door thresholds), and even Catlinite (pipestone). Some of this stuff will cause problems with the tires on the blade wheels. I replaced mine with multi wraps of friction tape years ago, and haven’t had a problem since. The Catlinite, and sawdust from Myrtle gunstocks, will do you real damage without a respirator.
Hungry Horse