# What is flat countersunk?

## What is flat countersunk?

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Also known as a flat-heat screw, a countersunk screw is a type of screw that’s designed to rest flush with the object or surface in which it’s inserted. They are called “countersunk screws” because they “sink” into objects and surfaces. They feature a flat head that tapers along the shaft.

### What is the angle of a metric countersink?

60° 82° American inch screws (UNC, UNF, UNS) 90° ISO metric.

What is the flattest screw head?

Flat Head (82 degrees) – Standard countersunk flat head screw. Allows for flat, smooth surface after installation. Flat Undercut Head (82 degrees) – Used instead of standard flat head for some short sizes. Allows for more shallow countersinking than standard 82 degree flat heads.

What’s the difference between countersunk and double countersunk?

What is a double countersunk screw head? Improved design on the countersunk head to give additional head strength and assist countersinking. Small ribs on the countersink to assist completion of countersinking. A countersunk head with a slight raised dome for an attractive finish.

## How are countersink angles measured?

Since the countersink has a 90° included angle, bisect that angle with the centerline of the hole to create two equal 45° angles. Subtract the existing hole diameter from the countersink diameter. Then divide the answer by two because ½ the difference is on each side of the hole.

### How do you specify countersink on a drawing?

Write the dimensions of the countersink, giving first the diameter of the drill hole, then the angle of the countersink, followed by the diameter symbol and the diameter of the larger hole. This dimension can be given either with a diameter symbol first, or with the word DRILL after the first diameter.

What are screws with flat bottoms called?

Countersink screws: This type of screw is preferred when the craftsperson wants a smooth, flat surface. When fully inserted, a countersink screw should be flush with the material’s surface. One of the most common types of countersink screws are drywall screws, which have bugle-shaped heads.

Why are there flat head screws?

Flat head screws are good for wood as they prevent overtightening and thus help prevent stripping.

## When should you not use countersunk screws?

When building furniture, manufacturers often use countersunk screws so that the heads don’t protrude. If the head protrudes out of a piece of furniture, such as a recliner, it will likely be uncomfortable to consumers to use. Therefore, wooden furniture is typically manufactured using countersunk screws.