I use to only buy Coats and Clark for my older machines it worked great, no problems after making sure I used the same weight for top thread and bobbin. In my Bernina, I have been using Signature and Gutermann, bought on sale of course, I kept breaking the Coat brand so tried others until I found the 2 that work best for my machine. I usually buy blades at Joann's but will look into Harbor Frieght and the other sites Thank you for the information.