Thread Inserts

[Billh50]

I have used the type shown in the past and they work real well for applications where there could be a chance of the bolt seizing slightly. The 4 pins keep the insert from turning when applying torque to remove a bolt. I now use heli-coils as I have a full set of taps and insert tools as well as a lot of inserts that a friend gave me.

 

[Terrywerm]

Helicoils are good also, but a full set of taps for them can get expensive. The nice thing about the locking inserts is that all you really need is standard taps to prep the hole for them. BUT Helicoils definitely are the winner when there is a limited amount of material available to work with.

 

[royesses]

When I worked for caterpillar the Keenserts as Nels shows were standard thread repair inserts. They are very strong but quite large in diameter. For aftercooler boxes and front covers,etc. the standard Heli-coils were the only ones that would work. I lucked out at Harbor freight one day, found both SAE and metric master thread repair kits at a parking lot sale stuffed under the back of a table. No price listed. I asked the manager and he said how about $20.00 each. I swooped them up at supersonic speed. They use standard heli-coil inserts and have the drills, taps, installation tools and thread inserts. They are excellent quality. I have used them many times. One time I can say that HF has a quality tool at a bargain basement price.
They are also sold at many places on the internet for quit a bit more.