Thread Repair (helicoil)

[yankee99]

Here are 2 main dealers in Thailand, you can get their address and phone number from clicking on the Map locations and scrolling down. Usually your application will be be Stainless Steel Helicoils,you will need a special tool to insert them yourself,but no doubt the supplier will advise you!

http://www.stanleyengineeredfastening.com/contact/global-locations#asia

All hellicoils are stainless, or should be and I wouldn't trust a Thai dealer for any advice, get them from Europe or the States, maybe Oz.

The good kits are supplied with a plastic insertion too and a proper plug tap, you merely drill the hole and tap down to the depth of the hellicoil plus about 1mm.

Never glue them in, as they rely on being expanded into the tapped hole as you screw the bolt in, if you use a locking compound the internal hellicoil thread will be too small.

That is why a tapered tap is no good, as the hellicoil will keep going and contract on the bolt thread.

I am no expert on taps but since the holes are deeper then the coil not sure matters. The important thing is the kits are available from hardware house and the price is good. They appear to be made in germany or china and sold from a german company. Almost forgot they work great!

[AllanB]

Here are 2 main dealers in Thailand, you can get their address and phone number from clicking on the Map locations and scrolling down. Usually your application will be be Stainless Steel Helicoils,you will need a special tool to insert them yourself,but no doubt the supplier will advise you!

http://www.stanleyengineeredfastening.com/contact/global-locations#asia

All hellicoils are stainless, or should be and I wouldn't trust a Thai dealer for any advice, get them from Europe or the States, maybe Oz.

The good kits are supplied with a plastic insertion too and a proper plug tap, you merely drill the hole and tap down to the depth of the hellicoil plus about 1mm.

Never glue them in, as they rely on being expanded into the tapped hole as you screw the bolt in, if you use a locking compound the internal hellicoil thread will be too small.

That is why a tapered tap is no good, as the hellicoil will keep going and contract on the bolt thread.

I am no expert on taps but since the holes are deeper then the coil not sure matters. The important thing is the kits are available from hardware house and the price is good. They appear to be made in germany or china and sold from a german company. Almost forgot they work great!

It makes a difference because the hole you drill is the tapping size of external part of the hellicoil and much bigger than the bolt which fits the internal thread.

I have quite a lot of experience with helicoils, all our aluminium bodied winches had them fitted and on one occasion the manufacturers locktited them in, thinking they would be more secure and we couldn't get most of the bolts in. Tapping them was difficult because they were stainless and removing them wasn't easy either.

When fitting them ourselves, we actually used a taper tap, followed by a plug tap, which was easier and marked the depth on the tap with tape, but the plug tap has a slight lead, so shouldn't be a problem for a 1off. With the right (quite high) torque setting we never had a problem.

I would say don't go the cheap easy route, if they pull out you are in for a lot more work having drilled such a big hole, if they jam is is a pain, so do it right and it is a good as new.

[Spoonman]

That tap that was supplied with the kit one would have to think is fit for purpose.

[AllanB]

That tap that was supplied with the kit one would have to think is fit for purpose.

There are plenty of things on the market that don't work too well and many that don't work at all. The Chinese (and others) have a habit of copying things, but don't get it quite right, I guess that is why we buy Honda.

This guy seems to want to do it right, otherwise he would simply go up a thread size.

[yankee99]

If they fail i will come and repost although I doubt they will. If i was doing a spark plug hole i would be extremely precise.

[Spoonman]

The difference between a taper tap and a plug tap is the difference of the lead in angle. provided there is enough "bottom" in the hole to allow the taper tap to cut a full thread I don't see what the issue is. in the case of the OP the hole does not have a bottom so if the tap was run all the way through it will be OK.

[VocalNeal]

I've used these before with success on aluminum VW heads for exhaust. Screw in then punch in the tabs to lock the insert.

Why because that is what the place I worked had in the stores.

[Garry]

Use a finishing tap to complete the threading of a hole never to start one. That's where a tapered tap comes into play. The tap set I use normally would have a starting tap, intermediate tap and a finishing tap. I was trained to use this method of taps on both heli-coils & inserts, but inserts are another issue.

Sent from my SM-T211 using Tapatalk

Edited June 2, 2014 by Garry

[AllanB]

Use a finishing tap to complete the threading of a hole never to start one. That's where a tapered tap comes into play. The tap set I use normally would have a starting tap, intermediate tap and a finishing tap. I was trained to use this method of taps on both heli-coils & inserts, but inserts are another issue.

Sent from my SM-T211 using Tapatalk

Hellicoils are normally quite short, so no need for an intermediate, or second tap and i have never seen one for a hellicoil. The plug tap is used to stop the progress of the hellicoil without jamming.

But, if the OP is dealing with a through thread, then the taper tap will be okay anyway.

[yankee99]

Seems if its a closed hole the taper tap should be ok. You only insert the helicoil 1\2 turn past flush so no way will it reach the taper part of the tap or am i missing something?

[Garry]

Use a finishing tap to complete the threading of a hole never to start one. That's where a tapered tap comes into play. The tap set I use normally would have a starting tap, intermediate tap and a finishing tap. I was trained to use this method of taps on both heli-coils & inserts, but inserts are another issue.

Sent from my SM-T211 using Tapatalk

Hellicoils are normally quite short, so no need for an intermediate, or second tap and i have never seen one for a hellicoil. The plug tap is used to stop the progress of the hellicoil without jamming.

But, if the OP is dealing with a through thread, then the taper tap will be okay anyway.

Oh undrstood, every situation has a possibly different process requirement to get the end result.

Sent from my SM-T211 using Tapatalk

[VocalNeal]

Seems if its a closed hole the taper tap should be ok. You only insert the helicoil 1\2 turn past flush so no way will it reach the taper part of the tap or am i missing something?

I guess that depends on the thread depth of the original hole and the length of the helicoil? From memory helicoil sets only have two taps?

[BSJ]

Thanks eddie for the info.

Went to hardware house on 36 this morning about 15 km from bira speedway. Asked the first attendant i saw in my best thai (and phone pic) for a thread repair kit? He said follow me and in a locked glass case he showed me this.

@791 baht its a bargain! Funny as i have driven past this store numerous time and never noticed it. They have a huge sign in thai and a very small one in english with the store name. This just reminds me how handicapped i am living here and not knowing how to read thai.

This store is well stocked with things i dont normally see such as: copper flaring tool, 3/8 swivels, telescopic magnets and porta power just to name a few.

That's good news! About 15 km past Bira on the way to Rayong, yes?

I think you will really enjoy a trip to this store.

Heading out there tomorrow. I discovered a crack in the manifold on the little Automac compressor we have up the farm....and bought it down to take off to take to the guy on Suk that can solder it. But it fell to bits whilst getting it off! So I need a new manifold and a bottoming tap to clear the thread on the pressure switch.

After going to 6 shops in Pattaya and not getting a manifold I have high hopes for tomorrow!

The manifold looks something like this pix.

[yankee99]

I was there this morning looking at tig welders.