Determining Best Bit Size Needed for a Tapcon Screw

bit size needed for a tapcon screwThe use of the optimal sized bit is important for getting the most effective size and shape of hole required for the Tapcon concrete screw. Hole tolerance is critical, and must be achieved in order to achieve minimum holding values. This is why determining the bit size needed for a tapcon screw is a must.

When determining the best size of a bit for tapcon screw, there are two dimensions that need to be determined: the diameter of the bit required and the length of the bit. These two dimensions should match the Tapcon size in order to achieve the required holding values.


The bit for the tapcon screw should measure slightly smaller than the designated diameter of the tapcon. The bit can be a straight shank that fits into the Jacobs style chuck. For example, a chuck that requires a chuck key, an SDS style. For the large diameter tapcon, the Spline and SDS Max can be used.

All bits used for the installation of tapcon screws must:

  • meet ANSI B212.15-1994 standards
  • have a carbide tip
  • be used in a hammer drill set in the hammer and rotation mode

The diameter of the bit chosen is determined by the diameter of the tapcon being installed:

  1. 3/16” tapcon uses a 5/32” bit
  2. 1/4” tapcon uses a 3/16” diameter bit
  3. 3/8” tapcon uses a 5/16”
  4. 1/2” tapcon uses a 7/16” bit
  5. 5/8”tapcon uses a 1/2” bit
  6. 3/4” tapcon uses a 5/8” carbide tipped bit

The length of the bit is critical. This is due to the differences in the depth of the hole in the base material, which is determined for each length and specific application of tapcon used in order to meet minimum embedment depths. Each diameter of tapcon concrete screw has a minimum embedment depth for installation in order to meet minimum embedment requirements.

There are two lengths that are of importance in a bit used for installing a tapcon screw. These are: the overall length of the bit and the usable length of the bit. When using a bit, the overall length is the length of the bit measured from end to end. The usable length is the amount of the bit that can be used after the bit is chucked into the hammer drill.

The hole must also be drilled to a depth exceeding the depth of penetration of the tapcon screw in the base material. This extra depth to the hole allows space for dust created during the installation process to fall into and out of the way.

  • For the 3/16” and 1/4” diameter tapcon, the hole must be drilled a minimum of 1/4” deeper than the tapcon screw will penetrate
  • For the 3/8”, 1/2”, 5/8” and 3/4” diameter tapcon, the hole must be a minimum of 1” deeper than the tapcon will penetrate

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