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bodged thread repair

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Bill Phinn02/03/2023 22:11:31
1076 forum posts
129 photos
Posted by Bdog507 on 02/03/2023 09:42:58:
Posted by Pete Rimmer on 01/03/2023 19:06:47:
Posted by Bdog507 on 01/03/2023 16:36:22:

However, Timeserts are stronger. So for stripped sump plugs, & wheel spindle threads in fork lowers etc I use Timeserts.

Stewart.

There was a fairly well done comparison video some while back that found the opposite to be true.

It would be interesting to see that. I'll have to see if I can find it.

Stewart

This is one video that certainly doesn't find Timeserts to be stronger than coil inserts, although one flaw in the video as I see it is that the demonstrator is tapping all the samples by hand; as a result, some threaded holes will no doubt end up closer to perpendicular than others, and this may influence the holding strength of the female threads under test.

samuel heywood02/03/2023 22:46:06
125 forum posts
14 photos

I see the problem has been solved thankfully.

Just a thought~ shouldn't be beyond the realms of possibility for a home engineer to manufacture there own inserts of any material of their choice?

Not familiar with "Timeserts" but my impression of" helicoils" from my biking days was they do the job but always seem a sloppy fit on the bolt.

Many moons ago (maybe 30years?) my local friendly Yamaha dealer repaired a monkey metal cylinder head for me with various solid steel inserts~

He must have had some engineering experience as he did the job himself & did it well.

These were definitely the dogs danglies & much better than helicoil though to this day i've no idea as to the trade name.

Bdog50703/03/2023 07:23:31
38 forum posts
Posted by Bill Phinn on 02/03/2023 22:11:31:
Posted by Bdog507 on 02/03/2023 09:42:58:
Posted by Pete Rimmer on 01/03/2023 19:06:47:
Posted by Bdog507 on 01/03/2023 16:36:22:

This is one video that certainly doesn't find Timeserts to be stronger than coil inserts, although one flaw in the video as I see it is that the demonstrator is tapping all the samples by hand; as a result, some threaded holes will no doubt end up closer to perpendicular than others, and this may influence the holding strength of the female threads under test.

Good morning all.

That was an interesting video, but as you say there could have been variations in the angle of the thread. However, as most inserts are fitted in situ it follows that most threads would be cut by hand with consequent variations in the angle of the thread and the drilled hole.

I spent the best part of a day fitting dozens of 10mm Recoil inserts to some engine mounting plates from some class of Go Kart.. Being flat I drilled and tapped them on my pillar drill. It's the only time that I can recall where I didn't drill and tap by hand.

Also, if I recall correctly I was told that Timeserts are only for use in Aluminium. I may be wrong, but it was about 30 years ago when I bought my initial Timesert kit. What's more, as I said earlier the insertion tool has to be wound fully through the insert, and it didn't look as if the chap in the video did that. It's certainly more than the lower threads of the insert that have to be expanded, for the expansion tool will only just screw into the insert by a couple of turns if one uses just fingers.

I'd like to see a similar test done in aluminum with the drilling and tapping done by machine, and at least 10 of each would give a better indication as opposed to a one off.

As I said, I've yet to have either type fail when I've done the fastener up. I have had Helicoils fail when the owner has been fiddling with something I've Helicoiled in the past, but that could be ham fistedness on the part of the owner. I suspect that they cross threaded the fastener and dislodged the upper coil of the insert.

Either way, both types have their uses, and applications.

Cheers.

Stewart.

Mick Bailey03/03/2023 09:01:49
61 forum posts

Posted by samuel heywood on 02/03/2023 22:46:06

:....my impression of" helicoils" from my biking days was they do the job but always seem a sloppy fit on the bolt.

I've also found the same and in some cases had to machine up a better fitting bolt or stud rather than use a commercial one. Typically a commercial M6 thread will be between 5.75mm and 5.85mm in diameter. Making a screw with the die opened up and the thread cut to finish at 6mm results in a better fit. Annoyingly, Chinese-made Clarke kits with their rather inaccurate rounded thread profile are a better fit than the more accurately formed Recoil or Helicoil inserts.

duncan webster03/03/2023 10:58:27
5307 forum posts
83 photos

When I worked on aircraft gas turbines, all holes in ally were helicoiled from new. Bolts were not a sloppy fit. Helicoiled hole is stronger than direct tapped as the shear area is bigger, and the helicoil itself adjusts a bit to spread the load over more threads. I never did understand the last bit, it worked, so as an engineer I didn't worry about it.

A Smith03/03/2023 11:53:15
104 forum posts
4 photos

I'd go to a specialist motor/ motorcycle engineering firm that employs a good welder. They would have all the options and could select the most appropriate repair technique. There's a very good one near Bedford with which I have no connection other than as a satisfied customer.

mark costello 103/03/2023 21:06:40
avatar
800 forum posts
16 photos

When much Younger I spent My excess time lollygagging in an old time auto parts store. One day a customer came in carrying a very bent up piece of wire. He said that They were fishing many miles down river. They shut off their motor to fish and it would not restart. When peering down the spark plug They spied with Their little eye a piece of metal across the hole. They decided that after many miles use of the running motor the siece of metal was stopping the spark from reaching the fuel and shorting out. So they got in there and unwound the piece of metal. Do You see where this is going? Upon trying to put the spark plug back in They discovered the hole was now much too big. They had to row home with only 1 oar. Bought the wire in the shop among the public to find out what it was.

Many more stories like that.

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