not cheap but absolutely amazing Amana Tool - 55228 Carbide Tipped 82° Countersink with Adjustable Depth Stop & No- https://www.amazon.com/dp/B00ECCN37E/ref=cm_sw_r_cp_api_glt_fabc_9G800WMV28V44SF5ZVG7?_encoding=UTF8&psc=1