However, the bottoming tap cannot start the threading on an uncut hole, so it can only take part in the cutting process as the second or third tap. So next comes the bottoming tap that has the capacity to do this. Unfortunately, due to the shape it can’t create a thread all the way to the end of the hole. That is why it features a tapered bit, allowing the machinist to align it correctly. The intermediate, or plug tap, is used first to start cutting out material from a non-threaded hole. To create a thread properly, one would need a set of three taps that correspond to the same bit size namely the bottoming, the intermediate, and the taper tap. Therefore the tap drill chart is extremely important. The following charts show the diameter and length of the tapcon screw and the diameter and overall length of the carbide bit for the straight shank, SDS, SDS max, and spline bit.As you would expect, taps come in all forms and sizes in order to accommodate standardised screw threads. 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. There are two lengths when describing a bit used for installing a tapcon screw, the overall length of the bit and the usable length of the bit. 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 and for the 3/8”, 1/2”, 5/8” and 3/4” the hole must be a minimum of 1” deeper than the tapcon will penetrate. This extra depth to the hole allows space for any dust that is created during the installation process to fall into and out of the way to ensure proper installation. The hole must also be drilled to a depth exceeding the depth of penetration of the tapcon screw in the base material. The minimum embedment depth for each diameter of tapcon is as follows: Each diameter of tapcon concrete screw has a minimum embedment depth that it must be installed for the tapcon screw to meet minimum embedment requirements. That 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. The length of the bit that is chosen is critical.

Hole tolerance is critical and the use of the proper size bit is important to achieve the proper size and shape hole that is required for the tapcon concrete screw to achieve its minimum holding values. The 3/16” tapcon uses a 5/32” bit, the 1/4” tapcon needs a 3/16” diameter bit, the 3/8” tapcon requires a 5/16”, the 1/2” tapcon requires a 7/16” bit, a 5/8”tapcon needs a 1/2” bit and the 3/4” tapcon requires the use of a 5/8” carbide tipped bit. The diameter of the bit chosen is determined by the diameter of the tapcon being installed. a chuck that requires a chuck key, an SDS style and, for the large diameter tapcon, the Spline and SDS Max can be used. The bit can be a straight shank that fits into the Jacobs style chuck, i.e. All bits used for the installation of tapcon screws must meet ANSI B212.15-1994 standards, have a carbide tip and be used in a hammer drill that is set in the hammer and rotation mode. The required bit for the tapcon screw is slightly smaller than the designated diameter of the tapcon. These two dimensions must match the size of the tapcon being installed in order for the tapcon to achieve the holding value requirements. There are two dimensions that need to be determined: the diameter of the bit required and the length of the bit. The size of the bit is determined by the size of the Tapcon® being installed.

Pilot drill chart