I replied here with this same answer.... Use a file, sandpaper and steel wool to remove the sharp edges. Worked great on mine.
I have that exact cage on now and have not had a problem like that. I was getting cut underneath and used a file, sandpaper and steel wool to...
That is an interesting way for edging, but could be the reason you are failing on day 7. How about going without any stimulation at all and just...