Thread repair inserts

[DiscoDan]

 

[Firebrick43]

I am reading alot of stuff these days throwing rocks at Helicoil. Especially spark plug threads in aluminum heads.
I ain't done a bunch, but I have been using Helicoil for my whole life for lots of applications. So far, so good.

Helicoils are absolutely terrible for holes that have bolts removed/installed every day such in a fixture of an industrial machine that is changed over to different part types. Other than being cheap, there are much better solutions and have been for 30 years.

The best inserts bar none are timeserts. They are wonderful in every physical way, thin walled, strong, durable, just not cheap due to the tooling.

Ez-lok have a lot of knock offs, many that are of softer metal, beware of that, even the name brand ones seem to be of a grade 5 metal compared to other inserts being grade 8

Keenserts(AKA CatSerts as they are caterpillars prefered method) are the best solution imho for strength to cost ratio. If you have the space, they are as durable as timeserts, lock in place mechanically, and use standard taps/drills for install. You don't need the special tool even to drive in the locking pins if you are careful/talented with a punch. They are even used in aircraft and spacecraft.

As to the op worrying about the modified 60 degree thread? Rounded crest/roots make for a stronger thread. What is the issue with it?

Guardserts are absolute trash.

 

[Batmanacw]

Helicoils are absolutely terrible for holes that have bolts removed/installed every day such in a fixture of an industrial machine that is changed over to different part types. Other than being cheap, there are much better solutions and have been for 30 years.

The best inserts bar none are timeserts. They are wonderful in every physical way, thin walled, strong, durable, just not cheap due to the tooling.

Ez-lok have a lot of knock offs, many that are of softer metal, beware of that

Keenserts(AKA CatSerts as they are caterpillars prefered method) are the best solution imho for strength to cost ratio. If you have the space, they are as durable as timeserts, lock in place mechanically, and use standard taps/drills for install. You don't need the special tool even to drive in the locking pins if you are careful/talented with a punch.

I don't like the non-standard thread form on the outside of the Keenserts. It cannot be as strong as the full 60⁰ thread on the E-Z Lok. I'd plan to drill the hole a few thou tighter on the E-Z Lok OD for greater thread contact rather than less.

I could be wrong.....

 

[pontiac428]

Whatever you do, spend the extra in order to get the name-brand kits. I suckered for a nifty metric helicoil knockoff kit that came with all sorts of goodies in a fancy steel box. The taps look like they were ground by a 6-year old using a dremel, with burrs of mostly-hardened steel the size of caterpillars packed in the flutes. I was questioning if they were to be used in lieu of drill bits. The install and tang tools were fine, and the inserts were decent, but I only ever used them for minor repairs.

I'll have to look into some of these others, thanks for the info.

 

[Firebrick43]

I don't like the non-standard thread form on the outside of the Keenserts. It cannot be as strong as the full 60⁰ thread on the E-Z Lok. I'd plan to drill the hole a few thou tighter on the E-Z Lok OD for greater thread contact rather than less.

I could be wrong.....

I think your tilting at windmills. The crest and root of most SAE threads are done for production, not strength A rounded crest and root eliminates stress risers. Removing the tip is inconsequential as its mostly a stress riser anyway. Look at whitworth or Unified J threads how they round over the crest and root for improved strength.

In addition, the thickness of the wall and the larger thread contact of the outside threads of the inserts are so much larger than original fastener size that again its inconsequential. The superior heat treatment and quality of keenserts is apparent to the ezlok.

Do you really think that FAA/US military/NASA would approve keenserts for flight above others if they were inferior? Or Caterpillar only recommend them for critical repairs in 5000 hp marine engines?

 

[Jake M]

I spent a good deal of time looking into thread repair inserts today. I don't like the idea of needing lots of special taps to use Helicoil type inserts so I'm leaning toward the solid inserts like the E-Z lock type. I know the Helicoil type inserts are quite strong.

First off, what are you doing with them? What material, what job will they be doing? There really isn't one fix for everything.... If you don't have that answer..... STIs / Heli Coils. They're the most versatile, most forgiving of mediocre hand installation or damaged materials (Unless you HAVE to remove too much material for some reason...). Plus Heli Coils can be cut short for thin materials without compromise, they can be "stacked" without compromise should you not want to order out for the correct length, They're just the most universal, and when put into reasonable joints in reasonable materials, they still exceed the strenth of the parent material, and the strength of the bolt, which is about all you can hope for, right? Yeah, it's extra taps to buy... one set does 99 percent of anything that needs threads. And when you really want another type of insert, Plastics, Wood, Plywood..... Well, you won't exceed any bolt strengths probably, and there are yet more special inserts for that, but you'd be surprised how well a heli-coil can do there too. So if you're just making up a kit to be ready for the unexpected, STI is my recommendation.

Another similar video on the subject- Crazy strong bolts though, testing the inserts in cast iron.

 

[Batmanacw]

First off, what are you doing with them? What material, what job will they be doing? There really isn't one fix for everything.... If you don't have that answer..... STIs / Heli Coils. They're the most versatile, most forgiving of mediocre hand installation or damaged materials (Unless you HAVE to remove too much material for some reason...). Plus Heli Coils can be cut short for thin materials without compromise, they can be "stacked" without compromise should you not want to order out for the correct length, They're just the most universal, and when put into reasonable joints in reasonable materials, they still exceed the strenth of the parent material, and the strength of the bolt, which is about all you can hope for, right? Yeah, it's extra taps to buy... one set does 99 percent of anything that needs threads. And when you really want another type of insert, Plastics, Wood, Plywood..... Well, you won't exceed any bolt strengths probably, and there are yet more special inserts for that, but you'd be surprised how well a heli-coil can do there too. So if you're just making up a kit to be ready for the unexpected, STI is my recommendation.

Another similar video on the subject- Crazy strong bolts though, testing the inserts in cast iron.

I simply want to but a few sets of inserts to put on the shelf for general use without needing special tools. I think that is a pretty easy request.

Will I find a situation where I might need something else? Sure.

For $71 I can buy a E-Z Lok kit covering 3mm to 8mm and cover most repairs I might come across with no individual size kits required or special taps. For $50 I can cover #10 to 1/2.

As a hobby guy trying to cover most basic repairs the local Amish farmers and my family farm, I really don't know what they will drag in next. I'd like to be prepared.

If wall thickness is critical I can order thin wall E-Z lock or buy a Helicoil kit.

 

[Batmanacw]

I think your tilting at windmills. The crest and root of most SAE threads are done for production, not strength A rounded crest and root eliminates stress risers. Removing the tip is inconsequential as its mostly a stress riser anyway. Look at whitworth or Unified J threads how they round over the crest and root for improved strength.

In addition, the thickness of the wall and the larger thread contact of the outside threads of the inserts are so much larger than original fastener size that again its inconsequential. The superior heat treatment and quality of keenserts is apparent to the ezlok.

Do you really think that FAA/US military/NASA would approve keenserts for flight above others if they were inferior? Or Caterpillar only recommend them for critical repairs in 5000 hp marine engines?

I'm not NASA and I'm not fixing 5000 hp engines. I'm repairing farm equipment and goofing off in my garage. $10+ each is ridiculous for the repairs I would need them for.

The extra thickness would also be a nightmare on lots of stuff I'd actually do. I don't know what will come in but some things don't have much wall thickness.

Finally I can't afford to have several of each on hand for the next time an Amish farmer drags in a part that he needs to finish feeding his cows before he can go to bed.

 

[projectnut]

Another believer in Keenserts. They were the insert of choice for the company I worked for. They're a little more expensive than some other brands, but there's no doubt about the quality. We used up to the 1" size when building side plates for large production machines. A typical large machine aluminum side plate would have a dozen or more to mount motors, gear boxes, and spreader bars. At nearly $60.00 each we weren't buying them from McMaster.

There are situations where the original Helicoil is a better choice. More because of their physical size than anything else. Over the years I've used them to repair threaded mounting holes in various brands of small engines. The most recent was a stripped out mounting hole in an older Kohler 14 hp K series engine. The Keensert just took up too much room. I was afraid there wouldn't be enough material left to withstand the torque and vibration when the engine was working.

 

[Firebrick43]

I'm not NASA and I'm not fixing 5000 hp engines. I'm repairing farm equipment and goofing off in my garage. $10+ each is ridiculous for the repairs I would need them for.

The extra thickness would also be a nightmare on lots of stuff I'd actually do. I don't know what will come in but some things don't have much wall thickness.

Finally I can't afford to have several of each on hand for the next time an Amish farmer drags in a part that he needs to finish feeding his cows before he can go to bed.

First, I am sorry, yes keenserts are about 2-2.5 times more expensive than EZ Lok inserts, and yes, on moderate and low load repairs, they are sufficient.

I wasn't trying to infer that you were doing repairs to equipment that is critical of life/obscenely expensive equipment by quoting military aircraft, NASA and Cat equipment. I was trying to make the point that those organizations have spent 10s of thousands of dollars minimum testing different thread repair techniques, and your insistence on a weaker OD thread of keenserts would of been brought to the forefront if it was an issue. In many applications in these organizations Keenserts are the only allowed repair.

Your statement in the regard to the thread strength had me assuming that you were doing something of high strength. I am sorry for assuming that.

I really am trying not to be argumentative, just provide factual info, but EZ lok thinwalls and Keensert Thin walls mostly have the same wall thickness in a lot of the sizes. Keenserts do have a thickwall version as well that you may have been looking at.