Taps are usually designed to make screws or cut thread for bolts. The tap drill is applied to the plastic, wood and metal material. If you have drilled an improper hole which is small in size, then the drill will not fit on it for further processing. In the same way, large size hole makes it tough for the tapped to hold the thread in one place. It causes a bolt to cut out the thread when it goes tighten. For more details, you can use online drill charts for the calculation of drill bit required for a specific kind of drill. However, sometimes, access to drill chart or tap chart is not feasible. It happens when you are working in professional environment. If you know the basic formula, you can easily find the bit that is fitted for your tap drill.
Here are some instructions that you must fellow in order to perform the process of tap drilling.
First, you should measure the diameter of the specific tap with the use of micrometer. In this instance, you need to drill bit size of ¼ tap that is also listed in the tap chart. This diameter tap drill should be matched with the size of the thread pitch per inch. If you do the correct measure of the taps diameter via micrometer, it should be 0.252 inches. If you do the measure in the right proportion, it will improve the overall performance and efficiency of the tap drill machine.
Here is the formula that will help you to get the correct size of the bit. It is dh=dbm_0.0130 in which DH is considered the drilled hole size in the quantity of inches while Dbm is the diameter of the thread that is also counted in 0.252 inches. It is all on your choice if you want to use desired size of the diameter. For more size information, you can review drill chart as well. However, you should select the size ranging from 70 to 85 percent based on the type of material that you are using for tap drill task. While in the formula, NI is the number of inches per thread. You should apply the formula with the use of 84 percent depth of thread. It will help you to find the nearest bit size as given in tap chart for tap drill.
The process of tapping can be performed by using a set of taps. However, the use of tap drill also proves feasible to perform tapping. It can go faster via machine and displays more accurate results because the chances of human error are eliminated here. Finally tapping is achieved via using a single tap. Although, tapping with tap drill is more good, accurate and free of tricky actions.
If you want to overcome the problems generated from tap drill process, you must get some training of it. The appliance of special tools minimizes the chances of breakage in tap drill process. These tools are listed in drill chart and classified as conventional type of items. in the tap drill chart, the drill size, decimal size, and drill equi size is mentioned. You can view the detail in the drill chart in case of any problem.