IRWIN Tools Classic Series Steel Table / Miter Circular Saw Blade, 10-Inch, 80T (11670)

I have two of the Irwin Classic 7-1/4" 140 Tooth blades that are useless. The first one I used 2 or 3 yeras ago to build a work bench with OSB top and shelves. I probably cut a total of 16 feet of 7/16" OSB before it gave out. I thought I had done something wrong so I let it go at that. Then recntly I needed to cut some more 7/16 " OSB and the first 8 foot rip went great. I got about 18" into the second rip when the blade went dull and started cutting crooked. I smoked my way through the cut and looked for a reason why this happedned. I couldn't find one. I put the Makita combination blade that came with my saw and cut another 16 feet with ease. The Makita blade has cut hundeds of feet of wood. I now know that it is unnecessary to use a fine tooth blade to cut OSB for my purposes.

I purchased SIX 11170 10" steel saw blades. I am old fashioned and just like steel. The first one I opened cuts worse than the dullest blade I own. Less than a foot into some 3/4" plywood and it starting to smoke and got hard to push the piece through the cut. Tried a couple more brand new blades. Same thing. Switched over to my old used dull blade to get the job done. Something is wrong here... maybe a manufacturing error or something.