Repairing Guides

how to repair a bolt thread

by Jared Wilkinson Published 2 years ago Updated 2 years ago
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How to Repair Stripped Bolt Hole Threads

  • Partially Stripped Threads. Partially stripped bolt-hole threads often vibrate loose or let go before applying maximum torque. ...
  • Badly Damaged Threads. Symptoms of a badly damaged bolt-hole range from a bolt that loses grip when applying moderate torque, to one that spins freely.
  • Thread-Repair Insert. ...
  • Install Bolts Correctly. ...
  • Thru-Hole Repairs Using a Nut. ...

Part of a video titled How to Repair Damaged Threads on a Bolt - Kevin Caron
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You can't get down in there and be able to have enough room to spin that thing around down in a holeMoreYou can't get down in there and be able to have enough room to spin that thing around down in a hole someplace trying to fix like a stud on a motor. There's another way these are called thread files.

Full Answer

How do you re- thread a bolt?

To rethread a bolt, you will need:

  • A bolt thread repair tool/kit
  • Lubricating oil to reduce the friction caused by rusting
  • A vise to help secure the bolt in place when working on it
  • A wrench

How to repair damaged threads without a special tool?

How to Fix a Stripped Screw Thread with Inserts

  • Remove the Bolt. The first thing you will need to do is remove the bolt. ...
  • Clean the Remaining Threads. Once you have removed the bolt, use a clean rag, some compressed air, and penetrating oil to cleanse the remaining threads.
  • Find the Right Drill Size. ...
  • Screw the Thread Insert onto the Installation Tool. ...
  • Screw in the Thread Insert

How to restore bolt threads?

Whether your bolt is cross-threaded or has threads that are flat, there’s a fix. The first tool you could use is a thread file, or thread restoring file. This tool actually has 8 different sizes of thread pitch on it, everything from 11 up to 24. Taking the flat threads and running them over the file will get rid of them.

How can you loosen a bolt that has been welded?

What to Do When a Frozen Bolt Tosses a Wrench in Your Plans

  • Rusty Stuff. I’ve been fixing old rusty stuff since I was a kid. ...
  • Best Way to Loosen Rusted Parts. Patience alone may be the best way to loosen rusted parts since no matter what method you want to use, you need to use ...
  • Planning Ahead. ...
  • Let it Soak. ...
  • Leverage is King. ...
  • Cheater. ...
  • Downside of Cheating. ...
  • Broken Bolts. ...
  • Welder to the Rescue. ...
  • Drill and Tap. ...

More items...

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Can you fix damaged threads?

Damaged threads on a screw or bolt can often be fixed by running a die over it, and if a thread's damage is minimal, it may be possible to reform the threads by running a nut up and down them, though that runs the risk of the nut fusing to the thread (galling).

Can you Rethread a stripped bolt?

Restore stripped threads quickly with a rethreading kit A rethreading kit is an important part of any automotive toolbox. Use it to restore stripped threads on old, rusty nuts and bolts when you don't have time to search the stores for a replacement.

How do you fix a stripped out bolt hole?

In most cases, a threaded insert kit is the easiest way to fix a stripped bolt hole. The kit comes with a specialized drill bit, which allows you to enlarge the bolt hole. From there, you can insert the threaded insert. Once it's flush with the engine block, you can screw the bolt in.

How do you repair a bolt without a Rethreader?

0:111:34How to repair damaged threads without a special tool - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd what you can do is try to come in the bolt hole from the opposite direction like this. And thenMoreAnd what you can do is try to come in the bolt hole from the opposite direction like this. And then you drive this on it will correct those bent threads as it punches back out through the backside.

How do you fix a stripped thread in metal?

0:2916:18How to repair stripped threads in aluminium or steel - YouTubeYouTubeStart of suggested clipEnd of suggested clipYou can actually drill the hole out larger. And tap it to the next tapping sighs OH. So on thisMoreYou can actually drill the hole out larger. And tap it to the next tapping sighs OH. So on this component we've got three good screw holes. And one of them is stripped completely which is that one.

Can you Retap a hole the same size?

This is done in a similar manner as a tap, but the shaft of the part threads through the die as it cuts the threads. In most cases, parts like these can be re-threaded, but they must be done with the same size threads, you can't cut the next size smaller threads.

Can you Retap a threaded hole the same size?

This is done in a similar manner as a tap, but the shaft of the part threads through the die as it cuts the threads. In most cases, parts like these can be re-threaded, but they must be done with the same size threads, you can't cut the next size smaller threads.

How do you use a tap to rethread?

1:047:07How to Rethread a Hole Using a Tap and Die Set - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo to begin just grab the bit that you need in this case we need or use an m6 size bit and you haveMoreSo to begin just grab the bit that you need in this case we need or use an m6 size bit and you have two options on how you want to turn this bit and tap your hole.

Why does my thread get damaged?

Typically, thread damage on a a male thread (a screw or a bolt for instance) is caused when incorrect bolt torque is used, when thread fretting occurs as a result of prolonged vibration during machining applications, or when the threads become worn after extended use over time.

Does a gage edge fit into the remaining threads?

The gage edge will fit perfectly into the remaining threads when you have the correct gage blade selected (there will be no gaps between the gage's teeth and the edge of the screw's or bolt's remaining threads).

How do threaded parts work?

They are twisted by hand, and slowly work their way into hole being tapped. Threaded parts such as bolts, shafts, and other similar parts use dies to cut the threads. This is done in a similar manner as a tap, but the shaft of the part threads through the die as it cuts the threads.

What happens when you strip a bolt?

When you strip one out or break a bolt inside the hole, the threads are damaged. In some cases you can re-tap the threads with good results, but if the fastener is under high load or critical, then you will likely have to go to the next size up. These holes use taps, which cut threads into the metal.

What is a taper tap?

The taper tap is the most common tap design. This is the style used for creating new threaded holes. The first 8 to 10 cutting flutes of the tap are not full, they gradually build up to the full thread size. The taper is there to guide the tap in the hole and to slowly cut the threads in fresh material.

Why do taps have tapered flutes?

The tapered flutes help ensure that the tap is centered and vertical. We ran the tap all the way through the part, so that the bottom threads were touched by the full flutes of the tap. The chips in the relief grooves of the tap are called swarf, they should be cleaned off before putting the tap away.

How many flutes does a plug tap have?

The plug tap is in the middle, it uses 3-5 gradual flutes. Each tap style serves a different purpose. From the left- taper, plug, and bottoming. If you are repairing damaged threads, either of these taps will usually work, unless it is a blind hole, in which you need to use a bottoming tap.

What happens if threads don't match?

Some pitches overlap different sizes, so you have to use the chart to determine what size fastener you have. Thread size and pitch is critical to this type of repair. Using this style of pitch gauge, you can determine exactly what you have.

Can you use a nut to check threads?

In most cases, you can use a nut or bolt to check the threads. If that is not an option, you can use a thread pitch gauge, such as the ones that are included in this Gearwrench tap and die set. You need the gauge and a chart (seen here) to match the thread pitch on the gauge.

What is thread repair insert?

Thread-repair inserts come in a variety of materials and in a myriad of designs from domestic and overseas manufacturers. Timed thread body inserts, wire coil inserts and keyed inserted make up the three major families of thread inserts you’ll likely encounter.

What size drill do I use for a M10x1.25?

First, you would drill the hole with a 10.25mm drill (a standard M10x1.25 thread would use a much smaller 8.75mm drill). Then you would use an M10x1.25-S.T.I. tap. This S.T.I. version of the tap will have a major diameter of up to 11.787mm, whereas a standard M10x1.25 tap is about 1.5mm less in diameter.

Can you have a thread failure in the same hole again?

Done right, you’ll never have a thread failure in the same hole again.

Is stripper thread more common than ever?

As a result, it’s no surprise that strippers are more common than ever before. Since most of the threads on today’s vehicles are made of materials with just one-third to one-half the hardness of grey cast iron, it’s no wonder that more threaded holes experience thread damage than ever before.

Can Keensert be threaded?

That’s a much bigger hole which can be beneficial in some application where severe corrosion is prevalent in the original threads. The Keensert would then be threaded into the drilled, tapped and cleaned hole with the Keensert installation tool. Thread locking compounds can be used due to its solid body design.

Is threading harder than fasteners?

While the materials where threads live have become softer, the materials used for fasteners have in many cases become harder. In fact, some of the super-alloys used in high-performance head studs and rod bolts have hardness levels approaching that of tap (every try to drill out a broken tap?). As a result, it’s no surprise that strippers are more common than ever before. Since most of the threads on today’s vehicles are made of materials with just one-third to one-half the hardness of grey cast iron, it’s no wonder that more threaded holes experience thread damage than ever before. It’s been said, “If a threaded hole in a softer metal uses a fastener that is installed and removed on a regular basis, a harder-material insert is a must.” Unfortunately, the cost and time involved with installing inserts at an OEM level means that it will never happen on a large scale. There may be a few key, high-stress locations in an engine block or suspension component, but 99 percent of all the threaded holes will not come from the factory reinforced with an insert.

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