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There are two main types of systems for fixing mangled threading, and each has its advantages.

We’ve all had this happen at some point while tightening hardware: It feels like it’s snugging up nicely, and then it suddenly seems to tun too easily. Or maybe you were removing stubborn hardware and it broke off, requiring drilling out the broken bolt. Either way, your job went from “almost done” to “just getting started.” It’s a lovely feeling.

Luckily, there are two thread repair systems that put professional results within reach. Both have advantages and are applicable in many situations. We’ll show you step-by-step how each system works and recommend when you should use them.

HeliCoil makes stainless steel, spring-like thread inserts that replace the original threads. These come in kits with a number of inserts, an installation tool, and a tap to cut the threads the insert screws into. The kits do not come with the required drill bit to drill out your damaged hole. HeliCoil inserts are relatively inexpensive and are often available in a variety of popular sizes at the hardware store—which makes the likelihood of a same-day repair possible. The HeliCoil kit we used here costs $25 on Amazon. There are many companies making this type of insert now, so you’ll find them with many different names.

Time-Sert thread repair kits utilize a solid, threaded sleeve insert. The kit comes with every tool you need including a drill bit, a counterbore, a tap, an insert driver, and five inserts. The instructions are extremely thorough with helpful illustrations that clarify each step. Due to the machine-shop quality tools, Time-Sert kits are a lot more expensive than HeliCoil’s—the one we used cost $89 on Amazon. There are many other companies making similar repair kits for less money, but they often don’t include all the tools—or the ones they do are of a lower quality.

To show how each of these kits works, we bought both kits in exactly the same size and prepared identical, damaged, threaded holes to repair with them.

With the HeliCoil repair on the left and the Time-Sert on the right, you can see both have threads that look like new. On the HeliCoil insert, you can see a sharp edge in the lower left of the hole, where the spring-like insert starts. This edge, as well as the one at the bottom of the insert, are the weak points of the HeliCoil—they can occasionally get pried up in certain circumstances and provide a point for the repair to fail. The Time-Sert insert, being a solid sleeve, is a more robust solution.

While both types of inserts will repair threads in many situations very well, there are definitely times you should use one over the other. Stripped-out spark plugs are one such situation. There are Time-Sert kits designed specifically this purpose. The solid sleeve top to bottom, as well as the way the threads lock in at the bottom, ensure the spark plugs will seat and seal properly. Additionally, if you have expensive or rare steel or aluminum castings, like engine blocks and machine parts, the Time-Sert is the way to go.

One consideration is how often the threads will be used. Once it’s re-assembled, will you ever have to take apart the repaired item again? Or does it hold a cover on a piece of equipment that gets cleaned frequently? In the first case, definitely consider the less expensive HeliCoil, but in the second, I’d recommend the Time-Sert. Lastly, how quickly do you need to get the repair done? Today? In that case, head to the hardware store—they might have what you need on hand in a HeliCoil kit or even just the inserts. If you can only find the insert, you can look up what size drill and tap are required—and if you’re careful, you can make an installation tool out of a bolt.