Drilling For Rocket City Type Control Horns
I usually predrill my hardpoints before I install them in the wing or tail core. A V block stood on end helps to keep the dowel centered on the bit. Use a forstner bit or a piece of sharpened brass tubing to drill the dowel hole in the surface. Keep the surface taped to the shuck while you are drilling. If the hole in the surface is not perfect don't worry about it you can fill in any voids with epoxy and microballoons. You can also adjust the dowel to ensure that the horn bolt is properly aligned.