When making holes to stretch the hide, I find a stone awl works wonders (a really sarp pointy knife will work too). lace the holes about 2" apart and make the slits at a 45 degree angle. Make sure there is lots of extra space on the frame as the hide will increase in size. If you are poking through when scraping, use something less sharp to get the job done (shaving the hairs is not as good as pulling them out, gently). I have found that a river cobble rubbed in a circular motion works well for taking the hair off, and it will not puncture the hide as you go (keep the stone wet, and rinse the hair off as you go). If you are brain tanning, the same rocks for the braining step can be used.