Combination countersink/pilot hole bits like those from Snappy are great to have around. They save time and keep the conical chamfer centered on the clearance hole. But there are two potential downsides: 1) when you need a size you don't have on hand; or 2) if you lose or break one of the pilot hole bits. Though not unheard of, if your project calls for larger clearance holes closer to 1/4", suitable combination bits are uncommon in most tool kits. Even if you have the right size, you can still misplace or break the bit. Without a backup or replacement bit compatible with the countersink portion, you must stop work. Of course, you could use a traditional dedicated (non-combination) countersink you lose the advantage of foolproof centered cones, and frequent bit changes cost you time. This is where these adjustable countersinks really shine.

Features:

• 82° Cutting Angle Carbide tips stand up to wood, composites, and non-ferrous metals like aluminum.
• 1/8" to 1/4" size range.
  
  • Actual range is slightly wider from 7/64" to 9/32"
  • Also works with metric bits from 3mm to 7.2mm
  • See the handy equivalence chart in the documents tab above
• Will work with virtually any type of drill bit within the specified size range: brad points, standard twist bits, and so on.
• Additional Uses:
  • Can be flipped upside down and used as an impromptu adjustable drill stop at no extra cost!
  • Widen existing holes by using a bit or drill rod of the same diameter as the existing hole, and use the countersink to create a perfectly centered starting recess for the next size up— no wandering or off-center boring to worry about.

Tips for Success:

• Make sure the countersink is as close as possible to perfectly center on the bit.
  • Tighten the screws gradually, switching back and forth between the two until the countersink is fully tightened.
  • Try to keep the points of the carbide tips hanging over the outer lip, as opposed to the flute, of the pilot hole bit.
  • Use the gaps at the side of the countersink as a visual cue to show how equally you've tightened the countersink.
• Mind your drill speed
  • If your drill has more than one speed, the lower end of the settings will generally improve bit and tip life.
• Using a metal cutting lubricant will significantly prolong the life of your bit when drilling in aluminum and other non-ferrous metals