I believe these hole saws will cut through the gates of hell. They will quickly gnaw a hole. If you are interested in finishing work or rough work, then these saws are for you. However, I need a plug, not a hole. Even with a drill with a clamped workpiece, I still have a gap. If there was a way to replace them with hole saws that make a smooth plug, I'd love to do that. It's my fault, not the tool.