First off I am a novice woodworker. I have a Crownshaw & Chapman 14" backsaw I purchased at a used tool store. Teeth were in bad shape so I filed them down completely. I've never attempted filing in new teeth but I took my time and filed them in at 10 tpi. They came out reasonably well. As I set them about 4 to 6 teeth broke off. Is it something I'm doing or is the steel defective or what? Any advice is appreciated.