A Quick Guide for Choosing the Best Combination Drill and Tap Set and How to Use it!
If you routinely create threaded holes in sheet metal or thin metal plates, you need one of the best combination drill and tap sets available.
Cutting threads in sheet metal or thin metal plates used to be a time-consuming and tedious process. First, you have to select the correct tap drill size, chuck up the drill bit and then drill each hole. Then you have to remove the tap drill and select the correct size tap, secure it in the drill chuck and tap each hole. And, in some cases, a chamfer might need to be cut to countersink a flat-head screw which requires a different bit.
Fortunately, tool manufactures have responded to the demand and designed a combination tool that is part traditional drill bit and spiral tap. This tool allows you to simply select the size tap size for the threaded hole you want to create, chuck it in your cordless drill or driver and you are ready to go.
How to Use a Combination Drill and Tap
There is a knack to learning how to use a combination drill and tap but its actually quite easy once you get the feel for it.
First of all, be sure and spot punch the hole location and select the correct size drill tap bit. Begin drilling the hole until it breaks through the opposite side. Once that happens start backing off on the speed as the tap threads grab the material.
Once the tap threads engage the metal, allow the tap to pull the drill motor along until the bit reaches the end of the tap threads. At that point there is a short section of the bit without any threads that allows you to dwell while the bit is still spinning.
The best combination drill and tap bits feature an angled shoulder just above the threads that allow you to cut an 82° chamfer that will remove the bur created by the tap. Be careful not to cut the chamfer too deep or you will destroy the threads, especially on a piece of sheet metal.
Once you have drilled, tapped, and chamfered the hole you must reverse your drill and gradually withdraw it until the tap engages the threads while you apply just enough pull as the threads push the bit and drill motor along.
The 82° degrees is the correct angle for countersinking a piece of thin steel plate where you intend to use flat head screws.
Once you get the hang of it you can drill, tap, and chamfer holes very quickly.
I am a firm believer in buying the best quality tools my wallet will allow, especially if you rely on your tools to put food on the table. But sometimes a more budget-friendly option makes more sense such as for the DIY guy or home workshop.
Here are the 5 Best Combination Drill and Tap Sets available starting with the more expensive professional grade. These drill tap bit sets are made from industrial grade HSS (High Speed Steel) so they will stand up under high production shop conditions.