How to Create or Repair Threads Using Taps and Dies

Knowing these terms is important when working with tap and die sets. "Tapping" happens when you cut or re-cut the thread into a hole or nut. Most auto mechanics and metalworkers have probably dealt with this problem. It can happen in the form of stripped sleeves or cut off bolts that need to be rethreaded. Learning how to use taps and dies allows you to solve serious problems in metal that would otherwise leave you high above the ground.

You use a "die" to cut or repair threads on a bolt or piece of metal. The metal strength of these thread cutters exceeds that of most sheet metal. With the right amount of oil and care, you can quickly and consistently cut or repair the threads of machined screws and bolts.

find the right TPI

Before you start threading, you first have to determine your threads per inch (TPI). You need it to grab the correct tap and/or die for the bolt, nut or hole. Most tap and die systems include some sort of gauge. They use many different "blades" to help you match the correct TPI of a bolt or nut. Some look a bit like a pocket knife. There are many such thread checkers on the market, and you can find one that works for you.

Select the corresponding Tap or Die

After determining the TPI of the bolt, you can select the corresponding tooling. Keep in mind that these kits are available in both metric and SAE. Manufacturers also have very small and very extensive kits. Both taps and dies have tapered threads. This helps them screw in the bolt or nut easily and gently re-engraves the threads as intended. Most dies will fit special wrenches that will quickly secure them. This gives you the necessary leverage to rotate it and guide it on its cutting path.

How about a combination drilling and tapping bit?

You may have seen some new drill and tap bits. These go into an impact driver or drill, allowing you to drill and tap in one step. A little more care is needed when manually tapping the holes, it's a wonder how they work.

But they do.

These bits will provide super fast hole tapping if you stick to the recommended materials and lubricate the bit during use. We've tried them in a variety of sheet metal and steel. Lining up the holes and keeping them straight and level was the biggest challenge with these drills.

Fixing and repairing threads in bolts

Using dies to secure threads on Phillips thread bolts takes just a few steps.

Fasten the bolts with a vise

Use a vise to hold the bolt in place first. Since you don't want to further damage the threads, we recommend only clamping the head of the hex bolt. However, if you need to clamp the bolt shaft, try one of the following methods to protect the bolt threads:

• use a few pieces of wood
• Find some rubber (like a bicycle inner tube) and put it in the vise jaws
• Use two pieces of leather

Align the die and start (re)cutting threads

Once the bolts are in place, be careful to align the mold so you're not leaning down, but straight down the bolts.

When you start to retighten the bolts, it will probably start to get hot. This is unavoidable when two metals are rubbed closely together. It's more noticeable when you use longer thread lengths. We recommend using a small amount of cutting oil to lubricate the die and keep it cool during use. Most tap wrenches are open at the top. Take advantage of this by adding lubricant without dismantling the mold. This also extends the life of the tap and die set.

As you thread the die down onto the bolt, you'll quickly feel it start to seize. You may have to back the die a little every few turns to clear the threads and allow it to cut better. This is to be expected, similar to drilling wood with a big drill. You'll know you're done once the die has moved down far enough for the bolts to go through the top.

Rethread holes and nuts with taps and dies

Screwing (or re-tightening) the nut is just as easy with a tap. Start by securing the nut with a vise.

Use a gauge to find the right size faucet

If you don't have matching bolts, use a gauge to select the correct size for the nut or hole you're screwing into. For those of you making your own nuts, you may want to use actual matching bolts to set the dimensions. This saves you from trying to force the gauge into a worn bolt. Depending on its location, this might not even be possible.

Don't panic if you come across a completely broken thread. You can always drill the holes and re-tap them for slightly larger bolts. You can even fill it and re-tap it.

Secure the tap and start threading

First, place the faucet in the wrench provided and secure. Next, place the faucet in the nut and start turning it down by hand, taking care to align it perfectly straight with the hole. As with molds, oiling is a must. Empty the tap frequently to remove debris that has built up in the threads.

in conclusion

Everything here is its own. Using taps and dies can really solve some nasty situations, and not everyone needs that kind of tool. But when you do, there is no substitute! Knowing how to use taps and dies well takes time. Eventually, you start to get a feel for the process. This speeds up your workflow.