

After finding the 1/4″-20 thread in the Inch Tap Drill Sizes table, we would slide over to the right-hand column of that row and discover that we need to use a #7 Tap Drill. The Machinery’s Handbook tells us that as a best practice, you should always default to the coarse thread first, unless there is a reason that you need a fine thread. The first option, 1/4″-20 is the coarse thread option (fewer threads per inch). (See Figure 1.) In the left-hand column of the table, you will see two 1/4” options. To determine what tap drill size you need, go to the “Inch Tap Drill Sizes” table in our Drill Tap Chart. Say that your drawing has a 1/4” thread call out.
#DRILL SIZE FOR 5MM TAP HOW TO#
Let’s look at an example to demonstrate how to use our chart.

PIPE THREADS (NPT) – This table lists the common NPT threads from 1/16” to 3”.METRIC TAP DRILL SIZES – This table lists the most common tap sizes, typically one coarse and one fine thread each, from M1.6 to M39.INCH TAP DRILL SIZES – This table lists the most common tap sizes, typically one coarse and one fine thread for each size, from a #0 to 1-1/2”.

#DRILL SIZE FOR 5MM TAP DOWNLOAD#
A link to download our handy Drill Tap chart is located at the bottom of this article. To create our chart, we pulled the basic numbers for the most common threads, class 2B, from the Machinery’s Handbook. To make your search easier, we have created our own Drill Tap Chart that includes only the information that you would most commonly need to properly drill and tap holes. You can also determine your tap drill size by digging into the Machinery’s Handbook, where you will find all of the different classes of threads listed. There are rules of thumb that you can use to calculate the tap drill size you need. This is usually referred to as a tapping drill for the size of the thread that needs to be produced. The most common way to produce an internal thread is to drill a hole and then use a tap to produce the thread.
