Possible Clues:

• Blade used to be lifted with letter to open?
• Letter saying something sharp
• Spam served on tips of asparagus which one's teeth go around
• Flier saying something that's sharp
• Carpenter's power-driven piece of machinery noticed on flier
• *Tool whose teeth rotate
• THIS IS NOT A DRILL
• One goes round very quickly and one's teeth are on edge
• Tool with a rotary motion
• Workshop machine