How do I remove helicoil

Drive something like a short straight scriber into the metal 'behind' the Helicoil. At an angle, so the top of it is unseated. then a small screwdriver or the 'scriber' can be used to bend it enough to grab it with a pair of snipe nosed pliers, so it can be unscrewed. It will damage the thread for the Helicoil slightly, but if your're careful the small area of lost thread will not be enough to make any significant difference to the strength, once a new Helicoil is fitted. I've had to do this quite a few times over years of fitting Helicoils so I know the results are satisfactory. Don't forget of course to run the Helicoil tap down again before fitting a new insert, and if it is a small diameter Helicoil, you may have to grind the pliers in order to grip the new 'tang' Mike.

A proper helicoil remover is rather like a pointed spade that you push into the insert and unscrew.

Then you swear, prise the end out with a scriper, and remove with pliers as above!

Ian

Never seen or heard of one, and I can't see how it would work, unless it uses the same principle as I use with a 'scriber' Mike.

They "cut" into the insert itself.

Snag is they don't stop the tip of the helicoil digging in, so you still end up hooking it out with the pliers.

IMO there's a very slight chance that they might work with some of the cheaper inserts, which are very lightly sprung and are easily fitted, but Helicoil inserts need to be reduced in diameter considerably before fitting, hence the special insertion tool. No way are they going to be unscrewed using a tapered tool, that's supposed to drive from a cut to the inside of the thread.

Maybe there is a better way than the way I suggest. If there is I'd like to hear it. Mike.

The removal tools form part of original Helicoil kits, so they are 'supposed' to work with the genuine article. As I suggested though, unless you are lucky and have good access you will probably sruggle.

Yes and it's the springing out when the driving tool releases the tang that means they grip to the new thread, in fact there seems to be more danger of a bolt driving them further in than pulling them out.

That's what I think, it would cause them to bite the wall better, I've only ever removed them by prising the first thread and then winding them around some thin nosed pliers and pulling them away from their thread.

AJH

Sorry but you must be thinking of some other makers kit. Genuine Armstrong Helicoil kits contain the two part insertion tool. A Helicoil tap. A short plain rod for removing the driving tang, and 5 or 10 inserts according to the size. With larger sizes, you get fewer inserts. There is also a card with tapping drill sizes etc. That's it. I have about a dozen Helicoil kits, bought over the last few years, but have been using them for over 40 years. None have ever contained a removal tool, and AFAIK their kits have never contained one.

so they are

TBH I can't see any special tool that could be designed to successfully remove a Helicoil from the top without damaging the Helicoil thread in some way. If such a tool existed I'd certainly buy one. Mike.

Yup. IME that's the only way to do it. Mike.

Thanks Mike. I tried that but as I screwed it in a bit far I was afraid I'd damage the thread. The top of the helicoil is in two or three turns of the thread. I suppose I'll have to pick at it even if I damage part of the thread and then retap. I wonder would using the bolt to remove the tang work better than trying to break it off with a hammer and punch.

John

You can normally snap it off with pliers. If you've got the right sized punch that'll work better than a bolt.

That wont work if as you say in your OP that the bolt binds on the insert if you screw it all the way in. This is probably because the tang end of the insert is engaging on the unfinished thread, created by the small 'lead' on the tap. IOW the insert is too deep in the hole. If it is, you'd be more successful in using a small screwdriver to simply lever the tang towards the outside of the hole until it snaps off. Not towards the middle, because it'll probably just spring away from it's seating, without breaking.

In any case, IMO all the above is academic. The insert is too deep. The length of a std Helicoil insert is 1.5 times the diameter of the thread. IOW a 10mm insert will be 15mm long etc. That is considered an optimum length, to ensure there's enough thread engaged to reduce the chances of the bolt stripping. If your insert is approx 3 turns too deep, and the bolt tightens before it reaches the end of the insert, it can't be screwing in

1.5 times the diameter, so the Helicoiled thread will be weak.

It definitely needs to be replaced, and yes, removing it will damage the thread, but the reduction in strength from that damage, is considerably less than the increase in strength you'll get from having 3 extra turns of thread. Mike.

so your options are to grind the tip of the tap down a little to get the extra threads cut, or reduce the helicoil length a little, or use an alternative, such as a 'timesert'

Use a punch and a hammer to break the tang, I have seen people use a long nose pair of pliers, but that is not recommended.

Mrcheerful

The tap can be shortened slightly at the tip, but as the cutting edges need to be at least as long as the depth of the thread, you don't usually gain enough extra depth to make it worthwhile, and yes, it's sometimes necessary to shorten inserts, especially if fitted to plates or flanges In the OP's case, the problem is that the insert has been screwed in too far. It is '2-3 turns' below the surface. I feel sure that as long as the hole is tapped to the maximum depth, a new insert fiitted just below the surface will not be too long, and wont bind at the bottom of the hole, which appears to be the case at the moment.

It is if it's possible with a spark plug thread, fitted with the head in place.:-) Mike.

I've come across this once with a hole a bit too shallow for the standard insert length and the taper on the tap a bit too long to get a parallel thread of sufficient length. Grinding the tap nose down a bit was enough to sort things out. I think the insert came out easily enough with a scriber under the top coil and then a pair of needle nosed pliers. I agree that I can't envisage a removal tool that could work by gripping the insert from inside and have certainly never seen one in a helicoil kit.

That is likely to be when I saw it, now I think about it. I would guess that helicoils are ferrous (can't be bothered to go and check) and the bit could be got with a magnet if you do drop it somewhere it shouldn't be.

Mrcheerful

Pack the hole with grease first, then it can't go far.

That would be nice if Helicoil inserts were ferrous, but they're not. They appear to be made out of a non magnetic hardened stainless steel. Mike.