My homemade implements are very similar. I had to experiment with the hammer a lot. When I used 10lb. plates over the pvc it was breaking the PVC all the time. When I switched to 5lb. plates it wasn't breaking as much. Less circumfrance on it made it slap onto the ground a little softer I guess. It still broke sometimes but less often that way. PVC is cheap as hell though I buy 20 foot pieces of it so I have a lot of extra for when it breaks.