Sharpening a Simmons Tree Shark and other concave BH's has been quite challenging to many and was for me for quite some time. Started using a Rada Wheelie 5 years ago and have been able to easily acquire a lethal edge. The blood trails on deer associated with a 4 1/4" entry and a 2 1/2" exit are superior.
Still I wasn't satisfied with edge that I was acquiring. Some guys can consistantly get that hair popping edge with the rada wheelie, while I fall a little short and especially weak in the valley.
I have been working with $2.99 Smith's sharpening tool for a while now. The hair popping edge is easily obtained with the ceramic crock stick section the full length of the edge.
I still prefer the rada wheelie for heads that need some roughing work and then finish with the small Smith's sharpening tool. One of these tools will be in my Safari Tuff quiver.
I am no longer searching for a method to improve the edge on the Simmons Tree Shark.
Hope sharing this fragment of knowledge serves as an aid to others.