What are Countersinks Used for?

A countersink is a cutting tool that cuts a conical hole into a base material and can be used for a number of different applications. The main use of countersinks is to cut a hole to allow the head of a countersunk screw or bolt, when fastened into the hole, to sit below or flush with the surface of the base material. They are also used after drilling and tapping applications to remove any burrs that are left behind.

Why Choose Champion Countersinks?

Champion Cutting Tool manufactures a wide variety of high-speed steel countersinks designed to perform a number of different applications, each with their own advantages in certain situations. Champion’s countersinks will provide users with a chatter-free performance and smooth, fast chip removal. Countersinks can be used in hand drills, drill presses, milling machines and lathes. Widely used in the glass, window and door industry, Champion countersinks will cut through metal, plastic and wood.

*It is recommended to use BruteLube to enhance the performance and extend the tool life of Champion Countersinks*

Most Popular Countersink Styles

Zero Flute Countersinks

Zero flute countersinks are a cross-hole countersink, the cone-shaped cutting tools feature a cutting edge provided by a hole that goes through the side of the cone. The cutting edge is formed from the intersection of the hole and the cone. Commonly referred to as a Weldon style countersink. Zero flute countersinks are best suited for softer materials including aluminum, wood & plastic for countersinking & deburring applications. They are offered in 2 styles:

• Piloted: Piloted countersinks are recommended for screws from 1/4″ – 1/2″ diameter
• Pilotless: Pilotless countersinks are recommended for bolt sizes from 0.073″ – 1-15/32″ & screw sizes #4 – #10 diameters

Single Flute Countersinks

Single flute countersinks are designed for use when the hole is too small for a multi-flute countersink or when multi-flute countersinks chatter. Widely used for machine and portable work at high speeds.

Three & Four Flute Countersinks

Similar to single flute countersinks, multi-flute countersinks are designed for chatter-free performance and are mostly used in portable applications.

Combo Drill & Countersinks

Combo drill and countersinks are designed to produce accurate conical holes in components that require machining between centers.

How to Choose the Right Size Countersink Diameter

You will want to choose a countersink that is larger than the bolt size of the hole. Countersink diameter = 1.5 x Bolt Size Hole Diameter.

Example: 1/4″-20 Bolt – Multiple the diameter (.250) x 1.5 = 0.375. You will want to use a 3/8″ countersink.

How to Calculate Countersink RPM Speeds

Countersinking is typically performed at 1/3 of the RPM speed of drilling. You will first want to calculate the speed by using the formula below, then you will want to divide that speed by 3 to get the countersinking speed.

Formula: SFM (surface feet/minute) x 3.82 / Cutter Diameter (decimal equivalent) / 3

Material	Surface Feet / Minute (SFM)	Sample Calculations for 1/4” Countersink Speed (RPM)
Aluminum	200 – 250	(225 (SFM) x 3.82 / .2500) /3 = 1,146 RPM
Mild Steel	100 – 110	(115 (SFM) x 3.82 / .2500) /3 = 586 RPM
Stainless Steel	30 – 100	(65 (SFM) x 3.82 / .2500) /3 = 381 RPM