Stump and root grinder

[Frank S]

Good invention May have to build one. How many Hp do you think would be needed ? What is the Diameter of the grinding blade ?
Thanks

G.Paul,At thje time I drew it I didn't know it but after searching later I found that I had I based the design in part at least to that of the DR 16.50 stump grinder

but since the OP stated that he has a 25 HP riding mower I took that into account as well. plus the fact that limited power can be transmitted through a drive belt which will fit on the pulley of the mower.
For this I drew the model with a set of 10" diameter 16 tooth cutters 1/2" thick the DR has 3 cutters I show the 1 that I drew with 6.
I further took into account that most modern 2 cylinder lawn tractor engines have a max RPM between 3200 and 3600 I have 1 that is governed at 3200 and 3 that are governed at 3600, my lawn tractors are older and have 6" Diameter power pulleys. The target RPM I was trying to aim for in the design would be between 4500 to 5500 or more This would offer in my opinion a good start point if I were to build 1 for myself (Which I may just to prove the design)taking that into consideration I drew the cutter pulley at 4".
there are a couple more features I had thought about but did not bother to design in as of yet since this was not to be a set of plans on how to build one but a guideline of 1 man's rambling thoughts portrayed on paper to another for 1 possible way to make a stump grinder.
Additionally to the camover clutch lever I drew in I feel that` there needs to be a way to adjust the belt I did not add this since there are many way by which this can be done. As I mentioned in my first post there would probably need to be some idlers added to insure the belt stays straight near the engine since it is being twisted up to 105° out of its intended running plane I left these up to the person deciding to make one the same with safety guards which are extremely important in my opinion
Also you may want a way to swing the grinder from side to side while sitting on the lawn tractor and 2 belts may be needed to transmit enough power to the cutter