I'm trying to find a self centering counter sink bit for counter-sinking limb bolt heads in a phenolic pad, instead of using the bezels and washers. I used one I bought at Lowes on the last one, but it wasn't the right degree bevel, and it cut like crap. I need to find one that is less than 90 deg with a 5/16" guide built into the bit. The bolt head is 5/8" across, and I'm guessing the bevel needs to be around 75 degrees. Anyone know what these pros use?