Serger cone thread and regular sewing machine are not the same thing. The serger thread isn't made as strong and is not as heat resistant. Regular SM thread is both. If your machine likes it, then use it as long it passes a breakage test. I just bought a box of thread for $1 and as a former user of of only certain brands, I can't believe I'm using these, but they passed the pulling test and my machine is happy, so what is, is.