You can use a Drill for with a grinding stone ( Clogs easily) or a Die grinder bit to open up the "thumb" grooves on a "35" Yokohama or a Bridgestone.
Edges can be squared up using an angle grinder ( I normally square up the tyre with a Die grinder and bit.. And only use them on the rear.) Where the lack of edge doesnt hurt as much.
A Propper tyre groover has issues "Edging" the tyre as the half of the wire not cutting the tyre overheats and stuffs itself. You have to use a lower temp and cut slower.
You can also use an angle grinder.....Yeah, Like no one else has!
Just dont cut the tyre cords.
Yokohamas use a Different Rubber for the core and the tread so It is easy to figure out where to stop. Bridgestone Thumb grooves are higher than the surrounding tyre so cut to that level.
Dunlops and Silverstones...Me never tried...
Ill post some pictures to explain.........................
: Take your pick.... 
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