JB Weld versus Loctite for grubscrews

[fafrd]

helicoils aren't expensive. And I bet one could be installed without even removing the cell from the battery.

I am fairly sure I pulled out another one today with 40 inch pounds. I stopped and screwed the stud in all the way then got it to hold 25 inch pounds. I'm so pissed. Lucky I have lots of cells to play with.

Less than 40 inch pounds isn't right for this purpose. If I can strip them with 40 then I guess I should try 30 and even that might strip one.

To make sure I understand correctly, are you saying you installed grub-screws (‘studs’) into your aluminum terminal threads then tightened a nut holding down a busbar to 40 inch-lbs and it pulled out the grubscrew (along with the aluminum threads)?

The Helicoil can self-tap into the M6 thread so you don’t need to do any drilling when installing a Helicoil?

 

[ArthurEld]

To make sure I understand correctly, are you saying you installed grub-screws (‘studs’) into your aluminum terminal threads then tightened a nut holding down a busbar to 40 inch-lbs and it pulled out the grubscrew (along with the aluminum threads)?

If I would have kept turning the screw the thread would have come all the way out. But I stopped and took off the nut and stud.
I put in a different stud and screwed it all the way to the bottom. Then I put the nut back on and torqued it to 25 inch pounds.

The Helicoil can self-tap into the M6 thread so you don’t need to do any drilling when installing a Helicoil?

The helicoil kit comes with the tap and the helicoil install tool and about 20 helicoils for $25.
Once you have the tap and install tool you can buy helicoils cheap. I already have a tap handle.
They're cheap anyway.

It's not hard but I will practice on a scrap piece of aluminum first.

The most difficult part is working with such a shallow hole. I assume once I've done a couple it will be quick.
I did it before but it was more then 20 years ago. And the hole was deeper.

 

[Bob B]

Have you considered this kind of stuff instead of JB Weld?

Robot or human?

 

[fafrd]

If I would have kept turning the screw the thread would have come all the way out. But I stopped and took off the nut and stud.
I put in a different stud and screwed it all the way to the bottom. Then I put the nut back on and torqued it to 25 inch pounds.

OK, so sounds like the aluminum threads themselves are not strong enough to withstand much over 25 inch-lbs of force and can pull out above that.

So I guess the two questions to ask are:

1/ will 25 inch-lbs suffice for acceptable performance?

2/ will JB Weld increase the effective pull-out resistance of the aluminum threads (perhaps by filling the small voids at the tips of the thread ‘triangles’ and gluing to both aluminum beyond the threads as well as the grub screw)?

The helicoil kit comes with the tap and the helicoil install tool and about 20 helicoils for $25.
Once you have the tap and install tool you can buy helicoils cheap. I already have a tap handle.
They're cheap anyway.

It's not hard but I will practice on a scrap piece of aluminum first.

The most difficult part is working with such a shallow hole. I assume once I've done a couple it will be quick.
I did it before but it was more then 20 years ago. And the hole was deeper.

OK, if it’s self-tapping and doesn’t need to be drilled, that’s easier than I was expecting.

I guess the main hassle is that the Helicoils need to be cut shorter?

What size Helicoil can you tap into the 6mm (M6) hole?

What size Helicoil are you planning to use?

Someone here is using very large Helicoils (10mm?) - did those have to be drilled or could even Helicoils that wide be self-tapped into our M6 holeS?

 

[fafrd]

Have you considered this kind of stuff instead of JB Weld?

Robot or human?

Looked at that earlier. Not really concerned about conductance (I’m of the view that the conductance that matters is to the surface of the Aluminum, another reason to be nervous about Helicoils...

 

[chops728]

If you still have some threads left in the stripped terminal --I'd try red loctite----If need be you can use a heat gun to get them out --as long as you have enough threads left to tighten the stud up --I have used this method on thermostat housings on aluminum intakes
make sure everything is clean and oil free

 

[blutow]

another alternative to helicoil - timesert

Amazon.com: TIME-SERT M6x1.0 Thread Repair kit #1610: Automotive

Buy TIME-SERT M6x1.0 Thread Repair kit #1610: Metric Inserts & Kits - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

I've used both and I find timesert to be better in aluminum. The thread is solid instead of a spiral like the helicoil (which sometimes gets hung up on aluminum during installation).

Timesert is more expensive for the kit, but once you have the kit the individual inserts aren't too bad. No affiliation, blah, blah, just a product I've had good luck with.

Only trick might be getting the right depth. Do these terminal holes have consistent depth and how deep are they? Shallow holes are going to be a challenge for helicoil or timesert because a tap can't get holes all the way to the bottom (even with a bottom tap).

I've got 16 lishen 272 cells on order and they are going in a van. If I have any questions about the integrity of the threads, I plan to put time-sert inserts into all of them and then loctite in some studs.

I personally would not use JBweld unless I was using it to fill a hole to be re-drilled and tapped. It might work OK, but it doesn't really flow like a thread lock compound and I'd be concerned with a hydraulic effect as the stud goes into the hole. Again, might be fine, but I'd definitely test on some sample aluminum before trying on a cell.

 

[fafrd]

I just want to add that I’m a bit surprised that there is still so much open debate about how best to connect these 280Ah EVE cells.

I mean, they have been available for well over a year now and it seems like there are hundreds of cells, possibly as many as 1000 that have been purchased and used by members over that same timeframe.

I jumped into this after discovering thus Forum and partly because it seemed like using these EVE 280Ah cells for DIY power walls was well past the ‘bleeding edge’ stage.

The 300Kgf ‘fixture’ issue materialized when the new datasheet emerged late last year and fine, something new to deal with.

But reliable electrical connections to these threaded aluminum terminals? I would have thought best practices for solving that issue was understood long ago.

Anyway, just my little rant. Perhaps I should start a survey to understand how many members with EVE 280Ah cells are using each various ‘solution’ and what % of those are happy.

I’d never heard of Helicoils until just this last week and it seems like enough members have just used stainless grubscrews secured by the aluminum threads (often with Loctite) that if that approach was problematic, we’d be hearing a great deal more noise...

 

[Solarfun4jim]

Best Epoxy Strength Test , JB Weld, Loctite, Devcon, QuikSteel fail - YouTube

Personally, i have tonight just bonded two nuts onto threaded rod using Araldite Steel. I prefer to go for ones that are 'metal' specific.
Araldite Rapid Fast Setting Epoxy 2 Part Strong Adhesive Glue 2 x 15ml Tubes | eBay

 

[ArthurEld]

OK, so sounds like the aluminum threads themselves are not strong enough to withstand much over 25 inch-lbs of force and can pull out above that.

So I guess the two questions to ask are:

1/ will 25 inch-lbs suffice for acceptable performance?

I think it will work for what I am doing. It isn't a long term solution.

2/ will JB Weld increase the effective pull-out resistance of the aluminum threads (perhaps by filling the small voids at the tips of the thread ‘triangles’ and gluing to both aluminum beyond the threads as well as the grub screw)?

It might work. Permanent thread locker might work too

OK, if it’s self-tapping and doesn’t need to be drilled, that’s easier than I was expecting.

Sorry, not self tapping the kit comes with a tap.
I forgot to say that the hole is supposed to be .25. M6 is .233 so it would probably work to just tap it without drilling.

I guess the main hassle is that the Helicoils need to be cut shorter?

The helicoils will have to be cut off. It won't be difficult to cut off but it will have to be done fairly accurate since there's not much depth and the cut will be where the screw starts so it will need to be done right.

What size Helicoil can you tap into the 6mm (M6) hole?

It will be a M6 helicoil tap. The tap diameter is about .3

What size Helicoil are you planning to use?

The helicoil inert will make the threads M6 again.

Someone here is using very large Helicoils (10mm?) - did those have to be drilled or could even Helicoils that wide be self-tapped into our M6 holeS?

I don't know but M6 is all I need.

There are probably lots of videos showing how to work with helicoils. When I get around to it, I will take pictures.

 

[ArthurEld]

blutow, the holes are 6mm deep.

 

[Hedges]

I think that with healthy threads, optional loctite would keep the screw in place.
Damaged threads, I don't think locktite would improve pull-out force.

With loose fitting threads or some deformed threads, I think JB Weld would fill the gaps to apply force uniformly, and bond to stripped areas, so I would use that to recover lost pull-out resistance.

Helicoil has same thread size with larger diameter, so that repair would improve pullout strength compared to the original smaller threads in aluminum.

Seems to me the JB Welded stud can be jacked out (restrain stud with an Allen wrench, don't hold battery case), so Helicoil remains a fallback option.

blutow, the holes are 6mm deep.

Anybody got an old wrecked cell they can investigate to see how tall the terminals are? (safely, of course)
Since the cells were meant to be welded they may not be much thicker than that. But if so, repairs could go deeper.

 

[Hedges]

Best Epoxy Strength Test , JB Weld, Loctite, Devcon, QuikSteel fail - YouTube

Personally, i have tonight just bonded two nuts onto threaded rod using Araldite Steel. I prefer to go for ones that are 'metal' specific.
Araldite Rapid Fast Setting Epoxy 2 Part Strong Adhesive Glue 2 x 15ml Tubes | eBay

4 pounds to 27 pounds, but pretty good lever arm that Allen screw gives, and small contact area under tension. Estimate 10:1 lever arm and 1/4 x 1/8 = 1/32nd square inch. 27 x 10 x 32 = 8600 psi.

Design within material properties and you might do OK.

There might also be something about having epoxy form a thin bond line, not have a thick epoxy component under tension, but I'm not sure about that.

 

[ArthurEld]

I think that with healthy threads, optional loctite would keep the screw in place.
Damaged threads, I don't think locktite would improve pull-out force.

With loose fitting threads or some deformed threads, I think JB Weld would fill the gaps to apply force uniformly, and bond to stripped areas, so I would use that to recover lost pull-out resistance.

Helicoil has same thread size with larger diameter, so that repair would improve pullout strength compared to the original smaller threads in aluminum.

Seems to me the JB Welded stud can be jacked out (restrain stud with an Allen wrench, don't hold battery case), so Helicoil remains a fallback option.

Timeserts use a bigger hole than helicoil so we can make it work.

Anybody got an old wrecked cell they can investigate to see how tall the terminals are? (safely, of course)
Since the cells were meant to be welded they may not be much thicker than that. But if so, repairs could go deeper.

I can mess around with my burnt up cell. It has one good terminal. And I can try to get a helicoil into the glob of material left at the other terminal.
I might run into chunks of the burnt off stainless stud though.

 

[FilterGuy]

The helicoils will have to be cut off. It won't be difficult to cut off but it will have to be done fairly accurate since there's not much depth and the cut will be where the screw starts so it will need to be done right.

This is the spot where I failed with Helicoils. How do you cut them without screwing them up. (No pun intended).

 

[ArthurEld]

This is the spot where I failed with Helicoils. How do you cut them without screwing them up. (No pun intended).

I was planning to try an abrasive cut off blade in a Dremel. It probably has to be done before putting it in.

 

[FilterGuy]

If you use JBweld, Loctite or any other thread glue, be very careful not to get it on the terminal pad..... it will create a slightly resistive barrier that is a bitch to debug. (don't ask how I know that!! ?)

Also, Don't count on any of the thread glue products to add much strength. You can have the best glue in the world... but it will pull out along with the soft aluminum threads.


The next time I purchase cells I am going to investigate having fortune style post laser welded on. I have thought about talking to Amy about it but I don't want to start the conversation if I am not ready to buy. What would be ideal is if she just carried a line of cells with the posts that we could order.

 

[ArthurEld]

Here's the helicoil kit. The tap is a standard size and it is possible to make an insertion tool out of a screw.

Amazon.com

This is cheap and gets good reviews - https://www.amazon.com/ABN-131-Piece-Metric-Thread-Repair/dp/B071NFMH8W/ref=sr_1_45

 

[fafrd]

I think that with healthy threads, optional loctite would keep the screw in place.
Damaged threads, I don't think locktite would improve pull-out force.

With loose fitting threads or some deformed threads, I think JB Weld would fill the gaps to apply force uniformly, and bond to stripped areas, so I would use that to recover lost pull-out resistance.

Helicoil has same thread size with larger diameter, so that repair would improve pullout strength compared to the original smaller threads in aluminum.

Seems to me the JB Welded stud can be jacked out (restrain stud with an Allen wrench, don't hold battery case), so Helicoil remains a fallback option.

Exactly what I was thinking...

But it sounds like this is not a common practice - anyone heard of anyone here on the forum who has already gone down this ‘JB Weld and fallback to Helicoil if it fails’ path?

 

[Hedges]

I was planning to try an abrasive cut off blade in a Dremel. It probably has to be done before putting it in.

I imagine cutting it off after installation, with the cutting disc at a slight tilt.

If necessary, dress with a stone after cutting.