If you use that ball head on the drill press in the concave area to to get it Aprox 1/8 even or 3/16 thicknesse it bends easer depending on what you need a 0.005 tapper on the core and horn is what I'm using for a long bow style with Aprox 8 in. Of reflex ,that gemsbok horn is crazy strong in compretion , sinew backed yew would make a awsome core/back with horn you realy have to keep a lot of reflex in order to over come the mass and get the performance out of these bows I'm not sure bamboo would do the job 1/3,1/3,1/3 sinew,core,horn is the standard recepe !