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Helicoils in Cell Terminals

ArthurEld

Solar Wizard
Joined
Aug 3, 2020
Messages
2,271
Location
Palm Harbor, Florida
I stripped the threads out of one of my EVE 280Ah terminals.
I decided to start a thread about Helicoils.
1611764493492.png
I ordered a kit that comes with a tap and install tool. There are a lot of different types and special tools but I am going to try the old standard with tang.
I will do some testing in scrap aluminum to be sure I can make it work. I have a bad cell to test on also.
I have installed helicoils before and they work very well. But I have never put one in such a shallow hole.
The ones I put in were bigger.

If I can't make it work, I'll try something else. Maybe JB Weld. :(
 
The holes have one thread per turn so the most threads I can expect to get in the hole is 6 because the original threads were only 6mm deep.
5 is probably more realistic. The helicoils have more than 6 threads so I have to cut a piece off.
I'll probably smash the part I'm cutting off in a vice. I'll try to use a cut off disk in a Dremel. (safety glasses)
 
I know there are people laughing at me for arguing against permanent thread locker in the past. ?
I wanted to be able to change stud lengths. But I'm good with 16mm so I'm going for it

I'm fairly sure permanent thread locker would have saved my threads.
 
I know there are people laughing at me for arguing against permanent thread locker in the past. ?
I wanted to be able to change stud lengths. But I'm good with 16mm so I'm going for it

I'm fairly sure permanent thread locker would have saved my threads.
Do you mean red or epoxy? I have older cells with some grease in the threads. I don't know whether either will work and it seems like they will be difficult to clean. I am leaning toward epoxy but it is messy. I don't have any fully stripped threads but a few that are iffy. I just want to fasten in grub screws permanently and be done with it.
 
Do you mean red or epoxy? I have older cells with some grease in the threads. I don't know whether either will work and it seems like they will be difficult to clean. I am leaning toward epoxy but it is messy. I don't have any fully stripped threads but a few that are iffy. I just want to fasten in grub screws permanently and be done with it.
I'm going to try the red. I am going to put it on threads I know are iffy. After it completely dries I'll try torqueing to 40 inch pounds. That will be good enough for me. If it doesn't work I'll have another helicoil repair job.
 
The holes have one thread per turn so the most threads I can expect to get in the hole is 6 because the original threads were only 6mm deep.
5 is probably more realistic. The helicoils have more than 6 threads so I have to cut a piece off.
I'll probably smash the part I'm cutting off in a vice. I'll try to use a cut off disk in a Dremel. (safety glasses)

Put a bolt or stud in the vice. Spin Helicoil on it. Cut with disk (in the direction that keeps it screwed on.)
Remove Helicoil. Dress leading edge of thread if desired.
 
On aircraft where aluminum is king, threaded inserts are extremely common. So I have used them a fair bit.

I prefer time certs over helicoils, as they are stronger overall, and less prone to binding/backing out with repeat usage. They are more expensive, and need a slightly larger hole though,
 
If you are hand tapping (not using a drill press or similar) a tap guide may be useful to keep the hole straight/square.
 
I have a drill press. The Timeserts and Keenserts look great.

Interesting that they purposely made it smaller in the bottom of the Timesert so it will push out at bottom.

1611778562520.png
 
Interesting that they purposely put a taper in the bottom of the Timesert so it will push out at bottom.

The keeners use the tabs while the time cert is permanently expanded by the fastener for a secure fit.
 
The helicoil would tighten at the bottom too because of the taper on the tap.
I think the timeserts and keenserts are better than helicoils. It's easier to mess up a helicoil.
But I will have helicoils here tomorrow and I can still do timeserts or keenserts if helicoils don't work because timeserts and keenserts use bigger holes.
 
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