How to Use a Drill and Tap Chart

When it comes to machining, the key to a finely machined piece is all in the tap. To properly tap a hole, you’ll need to drill it out and use the corresponding tap according to a drill and tap chart.

But, it’s not quite as simple as it seems. Today, we’re going to cover how to use a drill and tap chart and take a look at some of the best drill and tap sets that are on the market today.

What is a Tap?

A tap is a tool that features a threaded midsection, just like a screw or bolt would. A tap takes a hole in the material and adds threads to it, so it’s able to mate with the appropriate fastener. Before using a tap, you need to drill a hole in the material. The size of that hole corresponds with a tap, and once you create the hole, you use a tap to add threads to the piece of metal you’re working with.

Why Tap Holes?

With machined parts, it’s often necessary to add female threads to a piece of metal so that they can mate with a screw to provide a solid assembly. In some cases, you could avoid tapping in favor of using a nut on the opposite side of the fastener. But, in most cases, tapping the hole and attaching the hardware directly to the metal you’re working on is your best bet.

What is a Drill and Tap Chart?

A drill and tap chart is a large chart that provides all the information you need to properly tap holes.

All charts include values for screw size, major and minor diameter. From there, they tell you the proper size drill bit to use to make the hole for the tap. The chart will also let you know the correct size bit to use if you plan on tapping the hole, and the correct size bit to use if you’re just drilling out a hole to attach a fastener with a nut.

This comprehensive drill and tap chart includes everything you’ll need to know. Bookmark this reference so you can recall it whenever you need to.

Drill and Tap Conversion Chart

How to Use a Drill and Tap Set

Using a drill and tap set is quite easy. The key to producing properly tapped pieces is to make sure everything you do follows the drill and tap chart.

First, identify the fastener size you’ll be using on the tap chart. From there you’ll be able to find the proper bit to use to create the hole.

Next, put the corresponding bit into your drill. A drill press is optimal for tapping holes, but if you don’t have one in your shop, a corded or cordless drill will do the trick just fine. Put on safety glasses to protect yourself from any flying debris, and drill out your hole.

Once you have your hole, you can tap the hole to add the threads.

First, secure the piece you’re working with. A bench vise is the best way to secure the part, but you can clamp it to your workbench if it’s too large for a vise. Grab the corresponding tap from your tap kit, and attach it to the tap wrench. If you don’t have enough clearance to use a tap wrench, you can use a shorter t-handle wrench.

Stand directly over your workpiece, and place the tap into the hole, ensuring that it’s perfectly straight. Now, apply gentle pressure and begin to screw the tap into the piece. Within a turn or two, you should feel the cutting threads as they bite into your workpiece.

Continue to apply gentle pressure and turn the tap. For each clockwise rotation, you make, rotate the tap back out a half turn counterclockwise. This will break off any loose metal that’s left over as the tap enters the metal, and ensure a correctly tapped hole.

Repeat this process until the tap has passed through the entirety of the workpiece, and then remove the tap. At this point, you should have a correctly tapped hole that’s ready to add a fastener to.

Best Drill and Tap Sets

Image	Product	Price
	Irwin 117-Piece Deluxe Drill and Tap Set	$89.00	CLICK HERE TO BUY
	Bosch BDT11S 11-Piece Drill and Tap Set	$34.97	CLICK HERE TO BUY
	AccusizeTools 18-Piece Drill and Tap Set	$23.12	CLICK HERE TO BUY