Author Topic: Helicoils...  (Read 2070 times)

PonoBill

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Helicoils...
« on: January 20, 2021, 07:06:39 PM »
...My least favorite thread inserts, but they're a hell of a lot cheaper than the alternatives, and in the small metric sizes we use, they work fine.

Being away from my shop, where I have tools and supplies to do pretty much every kind of insert known to man or just weld up the hole and start over, I recently bought this set of 5mm to 12 mm helicoils with drills, taps, insertion tools, a wad of helicoils and tang punches from BangGood for less than a little bag full of 6mm Helicoil(r) helicoils. About 30 bux as I recall.

My eFoil has a pulled thread, oddly it was in the deep end of the skinny tail, the shallow one is fine. I drilled, tapped and inserted, then coated everything well with tefGel and Presto--good threads. If you do something similar remember that stainless on stainless has a serious tendency to seize, so use thread lube.



Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

surfcowboy

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Re: Helicoils...
« Reply #1 on: January 20, 2021, 09:05:08 PM »
I got the 6mm single version of that. If anyone is worried about doing this, donít be.

https://www.amazon.com/Highking-Tool-Thread-Compatible-Repairing/dp/B07VYGD8BC

red_tx

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Re: Helicoils...
« Reply #2 on: January 20, 2021, 09:06:43 PM »
Thanks Bill, it helps to see the tools to understand how it works. I understand some of the guys are tapping the GoFoil fuselage to avoid pedestal. I will do this with this kit.

Looks more straightforward after looking at the tools. Assumed one of them turns in the coil.
-red

jondrums

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Re: Helicoils...
« Reply #3 on: January 21, 2021, 03:33:14 PM »
if you're doing the gofoil tail, I strongly suggest "measure thrice and drill twice" - meaning, measure and mark very very carefully and then first drill a small hole perfectly centered, then follow up with a larger diameter hole.  Smaller drill bit wanders less, and the bigger bit will follow the small hole.  Even a little bit inaccurate off to the side and the tail will be cocked at a noticable angle.

PonoBill

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Re: Helicoils...
« Reply #4 on: January 21, 2021, 04:49:17 PM »
The best tool purchase I made in the last 20 years is an optical center punch. It enables superb precision in drilling even with a hand drill. The first time I used it I stomped around the shop cursing myself for not having bought one 50 years ago.

I coulda been a contender. Not cheap, but worth every penny.

Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Vancouver_foiler

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Re: Helicoils...
« Reply #5 on: January 21, 2021, 09:53:51 PM »
I have one of those kits. the tap works well enough. bi
up the punch thing broke almost immediately and the could themselves are of such poor quality I went out and bought actual heli-coils.
Just my two bits-garbage. works in a pinch.

PonoBill

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Re: Helicoils...
« Reply #6 on: January 21, 2021, 10:18:18 PM »
I don't like Helicoils to begin with, but I'm not about to pay $75 bucks for a single set of 6mm Timeserts when I already have all the sizes in my shop. Helicoils are always bitchy little things. I run the tap in and out multiple times to get a clean set of threads, and then lube the Helicoil with red Locktite--runs in easily, and then once the Locktite sets it won't back out if you happen to use a tight or slightly damaged bolt. I didn't bother knocking the tang out--that's always a little sketchy. For larger sizes, I just use needlenose pliers to break out the tang. In smaller sizes, I just count the number of threads and shorten the bolt to ensure it doesn't reach the tang. Five full turns of thread engagement are enough for the full strength of the threads, but in aluminum, I like 6 or 7.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Beasho

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Re: Helicoils...
« Reply #7 on: January 22, 2021, 10:21:27 AM »
I ordered the 6 mm Helicoil kit from Amazon so I could hang with the kids in the neighborhood.

I will also add a short option to my GoFoil tail rather than buying a SHORT Pedestal tail.

PonoBill

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Re: Helicoils...
« Reply #8 on: January 22, 2021, 12:09:34 PM »
I haven't found the helicoils in this kit to be a problem. the insertion tool is a simple one that is usually only applicable to small diameter inserts. Usually, the larger ones are inserted into a threaded female holder that compresses the coils a bit as they are wound into the holder. That makes the threads turn into the tapped hole being repaired a little easier and with less chance of cross-threading the insert. the problem with an internal-only winding tool is that the insert will have a lot of resistance when you run it in, and the slightly coarser surface of these cheap inserts makes the problem even worse. You don't want to use a lubricant to ease insertion because it will also make it easier for the insert to come back out. Using Locktite as a thread lube pretty much solves the problem, and the coarser surface of the cheap coils might even be a benefit once (if!) they are properly installed.

I wasn't paying attention yesterday and put a screw with slightly boogered threads into the repaired hole. Sometimes I find it hard to believe how dumb I can be, I literally just posted how that can be a big problem.

I cringed as soon as I felt it tighten up about two turns before it bottomed in the stabilizer. Stainless on stainless with messed up threads is about the same as welding the screw in place. I fully expected the threads to turn out when I had to use the impact driver to get the screw out, but they stayed in place, and a new screw with clean threads ran in and out without problems.
« Last Edit: January 22, 2021, 12:14:06 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

surfcowboy

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Re: Helicoils...
« Reply #9 on: January 22, 2021, 08:33:00 PM »
Iíve butchered a few installs and they worked fine.

The tang is hard to break but as you say, itís not the end of the world if they stay. Iím usually able to hammer it down if not off and I donít have trouble.

The loctite is a good tip.

Vancouver_foiler

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Re: Helicoils...
« Reply #10 on: March 07, 2021, 09:26:15 PM »
I haven't found the helicoils in this kit to be a problem. the insertion tool is a simple one that is usually only applicable to small diameter inserts. Usually, the larger ones are inserted into a threaded female holder that compresses the coils a bit as they are wound into the holder. That makes the threads turn into the tapped hole being repaired a little easier and with less chance of cross-threading the insert. the problem with an internal-only winding tool is that the insert will have a lot of resistance when you run it in, and the slightly coarser surface of these cheap inserts makes the problem even worse. You don't want to use a lubricant to ease insertion because it will also make it easier for the insert to come back out. Using Locktite as a thread lube pretty much solves the problem, and the coarser surface of the cheap coils might even be a benefit once (if!) they are properly installed.

I wasn't paying attention yesterday and put a screw with slightly boogered threads into the repaired hole. Sometimes I find it hard to believe how dumb I can be, I literally just posted how that can be a big problem.

I cringed as soon as I felt it tighten up about two turns before it bottomed in the stabilizer. Stainless on stainless with messed up threads is about the same as welding the screw in place. I fully expected the threads to turn out when I had to use the impact driver to get the screw out, but they stayed in place, and a new screw with clean threads ran in and out without problems.

So Pono, thanks f the threadlocker tip. Have you ever ran two or more helicoils into anything? I had to fix up my Axis mast(forgot tefgel) as I had to drill it out. I ran one deep and the other nearer to the top. The M8 screwed in all right, but I've just never heard of anyone doing that.

PonoBill

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Re: Helicoils...
« Reply #11 on: March 08, 2021, 06:29:17 AM »
I haven't, but I doubt you'd really need to. Deep threads are mostly to keep people from bottoming out a slightly longer screw and ripping out the threads. Full strength from almost any material being threaded is achieved after about 6 or 7 engaged threads, sometimes 4 or 5. Threads have limited strength, both in the material being threaded (the female side) and the bolt (male side). More threads increase the strength only to a limited degree unless the threads are made with extraordinary precision and have a precisely varied profile to accommodate bolt stretch. At full torque, unless the material the female threads are in is extremely stretchy, the first few threads are engaged and taking the full load and the rest are just along for the ride, both because the bolt stretches and because the profile of a typical thread is imprecise and varies. Thread failure starts with the fully loaded threads. That's one reason why you'll often see the top four or five threads ripped out and the rest remaining. The threads tore out until the clamping pressure was relieved enough. When you bottom out a screw and keep cranking you rip the threads out from the bottom up (bolt is being compressed) which is why it's a bigger problem, you can easily wind up with a screw that turns but won't come out. I hate that. It's a bitch to even drill the screw out because it spins happily along with the drill.

That's a long way to say that second Helicoil isn't doing a lot more than the end of the bolt waggling around in the air would do. At the far geeky end, there are more precise calculations for engagement but they all assume perfect threads.
« Last Edit: March 08, 2021, 07:00:56 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Vancouver_foiler

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Re: Helicoils...
« Reply #12 on: March 10, 2021, 08:36:10 PM »
Perfect. thanks Bill!

 


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