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JB Weld versus Loctite for grubscrews

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
 
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.
 
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...
 
fafrd said:
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?
Click to expand...
I think it will work for what I am doing. It isn't a long term solution.

fafrd said:
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)?
Click to expand...
It might work. Permanent thread locker might work too
fafrd said:
OK, if it’s self-tapping and doesn’t need to be drilled, that’s easier than I was expecting.
Click to expand...
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.

fafrd said:
I guess the main hassle is that the Helicoils need to be cut shorter?
Click to expand...
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.
fafrd said:
What size Helicoil can you tap into the 6mm (M6) hole?
Click to expand...
It will be a M6 helicoil tap. The tap diameter is about .3
fafrd said:
What size Helicoil are you planning to use?
Click to expand...
The helicoil inert will make the threads M6 again.

fafrd said:
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?
Click to expand...
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.
 
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.

ArthurEld said:
blutow, the holes are 6mm deep. :(
Click to expand...

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.
 
Solarfun4jim said:
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
Click to expand...

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.
 
Hedges said:
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.
Click to expand...
Timeserts use a bigger hole than helicoil so we can make it work.
Hedges said:
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.
Click to expand...
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.
 
ArthurEld said:
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.
Click to expand...
This is the spot where I failed with Helicoils. How do you cut them without screwing them up. (No pun intended).
 
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.
 
Hedges said:
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.
Click to expand...
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?
 
ArthurEld said:
I was planning to try an abrasive cut off blade in a Dremel. It probably has to be done before putting it in.
Click to expand...

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

If necessary, dress with a stone after cutting.

1611715835791.png

1611715930405.png
 
Hedges said:
I imagine cutting it off after installation, with the cutting disc at a slight tilt.

If necessary, dress with a stone after cutting.

View attachment 34760

View attachment 34761
Click to expand...
Yeah, this is definitely pushing into the ‘too much screwing around’ zone for me.

If my remaining threads + JB Weld fail to do the trick, fine, I’ll screw around with Helicoils.

But gluing grubscrews into the existing aluminum threads is a much easier way to go...

Abyine have any advice for the best way to clean the threaded holes before JB Welding-in the grubscrews?

Also, to all of you in contact with Amy about new 280Ah cell solutions, if Helicoils work so well, why has no one suggested that solution to her? Heck, with her volume she can probably even have a custom length special-ordered just for this application...
 
Hedges said:
I imagine cutting it off after installation, with the cutting disc at a slight tilt.

If necessary, dress with a stone after cutting.

View attachment 34760

View attachment 34761
Click to expand...
That is the tool I meant. And it would be hard to hold on to the hilicoil so putting it in first might be better.
It's easy to get a helicoil out without damaging the threads if I need to.
 
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ArthurEld said:
That is the tool I meant. And it would be hard to hold on to the hilicoil so putting it in first might be better.
Click to expand...
Let us know how it works.
fafrd said:
Also, to all of you in contact with Amy about new 280Ah cell solutions, if Helicoils work so well, why has no one suggested that solution to her? Heck, with her volume she can probably even have a custom length special-ordered just for this application...
Click to expand...
That is an interesting idea.
 
I got some silver-bond 2 - silver epoxy. From Atom adhesives.
I am planning on using it on the SS grub screws. (When my batteries arrive).
Hopefully it holds the screws in - I figure the conductive nature is just a bonus.
 
I believe the helicoils have a small 'tang' at the bottom you are meant to break off, but how about taking the coil right to the bottom of the hole and leaving the tang on. Add a spot of expoxy(pick your flavour) then screw the stud right down onto the tang...it becomes your stop, preventing you from going too deep? Once the expoxy goes off, you have the strength of the coil, plus the bond on the threads, plus an additional layer right at the bottom of the terminal that acts as additional protection. That should kill several birds with one stone as they say.
 
I measured the hole depth and it's about 8mm
I found a .25 diameter endmill with 0 radius so I can make the hole to size with a flat bottom.
The tap has a taper on the end so the treads at the bottom will get smaller.
I'll get 5mm of thread minimum. If the threads taper at the bottom, that will just help hold the stud in.
And even if the threads don't go to the bottom the screw can go to the bottom. Since the screw is chamfered it should still get the most possible threads.

The helicoil kit will be here Thursday

I'll decide about the tang and whether I need epoxy later
 
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ArthurEld said:
I measured the hole depth and it's about 8mm
I found a .25 diameter endmill with 0 radius so I can make the hole to size with a flat bottom.
The tap has a taper on the end so the treads at the bottom will get smaller.
I'll get 5mm of thread minimum. If the threads taper at the bottom, that will just help hold the stud in.
And even if the threads don't go to the bottom the screw can go to the bottom. Since the screw is chamfered it should still get the most possible threads.
Click to expand...

I'm used to taper taps and bottoming taps.
If Helicoil doesn't sell those, a second tap could be modified.

I also sharpen bits for flat bottom, to finish holes started with the usual shape drill.
End mill is nice if you have the equipment.
 
ArthurEld said:
I still plan to use permanent adhesive on all of the studs that still have threads as well.
Not sure if it will be thread locker or something else.
I'll have to experiment with that too.

Here's another possibility - https://www.loctiteproducts.com/en/know-how/fix-stuff/metal-glue.html#:~:text=Another option for gluing metal,brass, copper, and pewter.
Click to expand...
What are the reasons you think there may be something better for permanent adhesive of stainless threads into aluminum threads than JB Weld?
 
Hedges said:
I'm used to taper taps and bottoming taps.
If Helicoil doesn't sell those, a second tap could be modified.

I also sharpen bits for flat bottom, to finish holes started with the usual shape drill.
End mill is nice if you have the equipment.
Click to expand...
I know how to sharpen drills. But I have to get a grinder to mount on my workbench.
I will try to get away with using the tap as is but if I have to I'll get a second tap and grind off the end so I can get the threads to the bottom.

This makes me wonder how many people have their batteries torqued to 25 inch pounds. After seeing AussieInSeattle's exploding busbar, I don't think 25 inch pounds is safe. I want 50 inch pounds. And I don't want to have to deal with pulled out threads every time I try to torque my busbars down.
 
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