JB Weld versus Loctite for grubscrews

[Sillyputty]

Thanks a fantastic document - thanks for making that effort.

The only small aspect I’m not understanding is his you removed the tang at the end - the YouTube video I found was thru-hole, so he just had to push the tang through.

With the tang resting against the bottom of the cell, how did you remove it?

And the other question I have for you is if you were using a Helicoil to attach a permanent M6 grubscrew, when would you use Loctite Red? Both on the Helicoil when it is installed and again when the grubscrew is threaded (and the Helicoil has cured)?

I've successfully helicoiled one terminal and made the 'mistake' of installing the coil with the tang "up" rather than on the bottom, as that was what was shown in the particular video I watched. It was easy to install (and to break off) and seems just fine.

 

[fafrd]

There is no thread locker or glue used with hilicoils. You won't need loctite and it will be stronger than the holes with loctite.
But you could loctite it if you want to. I'm nut sure what would happen if you tried to take it out.

Yes, I understand that Loctite is not required with Helicoils, but the YouTube video I found about repairing aluminum engine threads with Helicoil used Loctite Red and since all my other grubscrews will be permanently installed with JB Weld or Loctite Red, I figure I may as well secure this one in Helicoil the same way...

I’m perfectly five never being able to remove the grubscrew (or the C

I had to use a pointy rod to get the tang out. It took a little moving it back and forth but it let go and came out.

Cool - thanks.

I mentioned leaving some taper on the tap so it's easier to start and so it cuts better. But that causes a taper in the helicoil so the screw will be tight at the bottom. I think that that is fine.

Oh, so the stock Helicoil tap has a mild taper and TOU left it as is? I thought you were just talking about the bottom and not grinding it completely flat but leaving a mild angle...

You only grinded the tap at the bottom / point, correct?

 

[zzyzx]

Anyone try this?

 

[fafrd]

Anyone try this?

Yea, that’s what we are discussing. ArtherEld has successfully used Helicoil to repair a stripped EVE 280Ah thread.

The 3 issues are:

1/ Drill but needs to be modified for a flat bottom (and 1/4” hold needs to be drilled to target depth).

2/ Helicoil tap also needs to be ground down to a close-to-flat bottom (so threads extend to the bottom of the terminal hole)

3/ Tang needs to be removed from the bottom of the hole (truckier than tang removal in a through-hole installation)

 

[zzyzx]

There is NO tang in this Helicoil.

 

[fafrd]

There is NO tang in this Helicoil.

Missed that. Very cool. Know where to purchase them?

 

[ArthurEld]

Yes, I understand that Loctite is not required with Helicoils, but the YouTube video I found about repairing aluminum engine threads with Helicoil used Loctite Red and since all my other grubscrews will be permanently installed with JB Weld or Loctite Red, I figure I may as well secure this one in Helicoil the same way...

I’m perfectly five never being able to remove the grubscrew (or the C


Cool - thanks.

Oh, so the stock Helicoil tap has a mild taper and TOU left it as is? I thought you were just talking about the bottom and not grinding it completely flat but leaving a mild angle...

You only grinded the tap at the bottom / point, correct?

The tap has a point on the bottom and it gradually tapers up to the full size.
I had to grind off the point and part of the taper. But the tap works better if you leave part of the taper. The taper helps guide the tap into the hole and it also gradually cuts the thread and leaves some material for the next tooth.

I think 3 threads of taper is good. But the top one is good too.

 

[fafrd]

The tap has a point on the bottom and it gradually tapers up to the full size.
I had to grind off the point and part of the taper. But the tap works better if you leave part of the taper. The taper helps guide the tap into the hole and it also gradually cuts the thread and leaves some material for the next tooth.

Got it - thanks.

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Seems like the biggest problem is that they would be tougher to cut to size than Helicoils, but if you need a grinder anyway to flatten the tap and drill bit, grinding down the end of one of these to match your hole depth doesn’t seem like that much more work...

 

[ArthurEld]

I didn't. I had used helicoils before and it was $18 for the kit so I just used it.

 

[fafrd]

I didn't. I had used helicoils before and it was $18 for the kit so I just used it.

Turns out the Brass Solid-wall variants are intended for wood and the ones intended for use in metal are hardened steel (so probably more difficult to grind back than I had hoped).

In addition, the M6 solitaire wall requires tapping an M10 hole, so conductive contact area with a lug is reduced much more than it is with a Helicoil and fall-back to thread an M8 grubscrew is not possible.

I’ll stick with Helicoil and hope I can remove the tang as effectively as you did...

 

[fafrd]

One more little update on the subject of JB Weld and grubscrews.

Since I had that partially-stripped grubscrew pull out, I figured I would try to secure a new one with JB Weld before drilling for Helicoil.

After cleaning with Acetone, I glued in a fresh grubscrew and did my best to orient it straight/perpendicular (tough without and threads to pull against).

I let is set for 48 hours but unfortunately, the grubscrew was not perfectly straight (could slide a piece of paper under one side while the other side was tight.

At that point, I decided to pull out the grubscrew but figured why not measure the torque required.

The JB Welded grubscrew in fully-stripped aluminum thread pulled out at 20 inch-lbs, so I’m a lot less impressed with the strength of JB Weld alone than I thought I’d be.

Is it possible that the JB Weld did not adhere to the sidewalls because they had oxidized? I don’t know.

I cleaned with a Q-Tip dipped in acetone and applied JB Weld as soon as it was safely dry (15 minutes later).

If anyone has a better cleaning process to get epoxy to stick to soft aluminum sidewalls, I’m in no rush to get this cell back in action and have plenty of JB Weld to try again...

After this latest discovery (only 20 inch-lbs of pull-out strength), I’m no longer interested in using JB Weld on my remaining unstripped threads and will be switching to Loctite Red.

 

[codfish]

One more little update on the subject of JB Weld and grubscrews.

Since I had that partially-stripped grubscrew pull out, I figured I would try to secure a new one with JB Weld before drilling for Helicoil.

After cleaning with Acetone, I glued in a fresh grubscrew and did my best to orient it straight/perpendicular (tough without and threads to pull against).

I let is set for 48 hours but unfortunately, the grubscrew was not perfectly straight (could slide a piece of paper under one side while the other side was tight.

At that point, I decided to pull out the grubscrew but figured why not measure the torque required.

The JB Welded grubscrew in fully-stripped aluminum thread pulled out at 20 inch-lbs, so I’m a lot less impressed with the strength of JB Weld alone than I thought I’d be.

Is it possible that the JB Weld did not adhere to the sidewalls because they had oxidized? I don’t know.

I cleaned with a Q-Tip dipped in acetone and applied JB Weld as soon as it was safely dry (15 minutes later).

If anyone has a better cleaning process to get epoxy to stick to soft aluminum sidewalls, I’m in no rush to get this cell back in action and have plenty of JB Weld to try again...

After this latest discovery (only 20 inch-lbs of pull-out strength), I’m no longer interested in using JB Weld on my remaining unstripped threads and will be switching to Loctite Red.

Any chance of repeating the same test, on the same hole, with Loctite Red? Would if fill the larger void? Would it set up properly?

 

[Sillyputty]

I glued in a fresh grubscrew and did my best to orient it straight/perpendicular (tough without and threads to pull against).

Thanks for sharing your experience. I think this may be why the JB Weld failed in this case: there was not enough surface (especially intact screw thread) for the epoxy to adhere to. Having as many screw threads available to lock-in the epoxy and prevent it pulling loose seems key to it working well enough for the application we're attempting. In other words, it needs both surface area and cantilevered surface(s) in order to both bond and resist torque. After having such a fun time with the one cell I damaged the terminals on by stripping them (whcih I fixed w/helicoil which did work well but is quite expensive) I plan on trying JB Weld on the remaining cells that have undamaged threaded terminals, using stainless grub-screws inserted to the bottom of the holes.

 

[fafrd]

Any chance of repeating the same test, on the same hole, with Loctite Red? Would if fill the larger void? Would it set up properly?

Loctite is not going to secure threads in a stripped hole - it is designed to harden in very narrow channels, not to fill large voids (such as the triangular-shaped channels of a thread within a cylinder).

That being said, once I have my Loctite Red, I may be able to perform an experiment in the interest of Science (and all of us DIYers .

 

[fafrd]

Thanks for sharing your experience. I think this may be why the JB Weld failed in this case: there was not enough surface (especially intact screw thread) for the epoxy to adhere to. Having as many screw threads available to lock-in the epoxy and prevent it pulling loose seems key to it working well enough for the application we're attempting. In other words, it needs both surface area and cantilevered surface(s) in order to both bond and resist torque. After having such a fun time with the one cell I damaged the terminals on by stripping them (whcih I fixed w/helicoil which did work well but is quite expensive) I plan on trying JB Weld on the remaining cells that have undamaged threaded terminals, using stainless grub-screws inserted to the bottom of the holes.

That had been exactly my plan (JB Weld instead of Loctite Red on non-stripped threads), but I no longer think it is worth it.

JB Weld is far more difficult to apply than Loctite Red, and believing it to be stronger, I was prepared to make than effort (and in fact have 6 of 16 cells secured with JB Weld now).

But now that I’ve seen how easily it pulls out in stripped terminals (~20 inch-lbs) and knowing from Arthur Eld’s work with Loctite Red that it will secure grubscrews in threaded terminals to at least 45 inch-lbs (the same max torque I have applied to my JB Welded grubscrews), I don’t see any advantage to using JB Weld instead of Loctite Red).

Did you have to grind down a 1/4” drill bit and the Helicoil Tap to repair your stripped thread? This thread is probably not the right place for it, but I would be very interested to read more about your experience using Helicoil to repair a stripped thread (since I need to do that to recover my stripped cell).

The grinding has me concerned, as does the need to drill straight (I have a drill press, but it is not tall enough).

 

[Sillyputty]

Did you have to grind down a 1/4” drill bit and the Helicoil Tap to repair your stripped thread?

No, but in retrospect I should have. After reading Arthur Eld's postings on helicoils, I realized that a) the tapped holes on the cells were even less deep than I thought, b) using drill bits and taps that were tapered made them shallower. The first terminal I did I ended up snipping off a part of the helicoil that extended above the holes surface due to this. The resulting thread did torque to specs and is holding. That said, on the second terminal of that same cell I measured the length of the screw thread of the bolts provided with the cells and drilled carefully down to that depth before inserting the second helicoil - something I would not have even considered had this cell not be quite damaged already during shipping. The resulting thread/helicoil process went fine and holds great - and it didn't appear I got anywhere near going trhough the terimnal into the cell itself.

 

[zzyzx]

No, but in retrospect I should have. After reading Arthur Eld's postings on helicoils, I realized that a) the tapped holes on the cells were even less deep than I thought, b) using drill bits and taps that were tapered made them shallower. The first terminal I did I ended up snipping off a part of the helicoil that extended above the holes surface due to this. The resulting thread did torque to specs and is holding. Taht said, on the second terminal of that same cell I measure the length of the screw thread of the bolts provided with the cells and drilled carefully down to that depth before inserting the second helicoil - something I would not have even considered had this cell not be quite damaged already during shipping. The resulting thread/helicoil process went fine and holds great - and it didn't appear I got anywhere near going trhough the terimnal into the cell itself.

As I await delivery of cells, I may be overthinking this Helicoil option again after reading so many post about damaged threads. I had planned to only insert Helicoils in my new, virgin threads before adding the M6 grub screws. I have always "assumed" that I did NOT have to drill out the original threads with a larger bit AND I did NOT have to tap the hole to accept the Helicoil and then my M6 grub screw. Is this true?

 

[Sillyputty]

I have always "assumed" that I did NOT have to drill out the original threads with a larger bit

In order to use the same size grub screw or bolt (M6 in this case) you do have to drill it larger to accept the helicoil. The helicoil exterior diameter in any instance will be larger than the existing hole/thread size. The interior of the helicoil will be the same size (M6).

I did NOT have to tap the hole to accept the Helicoil

You do have tap the hole IF you want to use the same size of bolt/grub screw (M6 in this case). I think you may be able to find a helicoil to fit the existing threads in the terminal (which are M6 in this case) BUT the resulting threaded area will be smaller diameter as a result, and you will the have to use a smaller diameter bolt/grub screw.

In order to do what you describe you would have to find a helicoil that fit the M6 threads that are already there, and then use smaller diameter screws/bolts to affix the busbars.

 

[fafrd]

As I await delivery of cells, I may be overthinking this Helicoil option again after reading so many post about damaged threads. I had planned to only insert Helicoils in my new, virgin threads before adding the M6 grub screws. I have always "assumed" that I did NOT have to drill out the original threads with a larger bit AND I did NOT have to tap the hole to accept the Helicoil and then my M6 grub screw. Is this true?

If you use Loctite Red to secure stainless grubscrews into your virgin threads, there is absolutely no need to mess around with Helicoils (unless you’ve convinced yourself that you absolutely need more than 45 inch-lbs of torque on your busbars/lugs).

Going to Helicoil is just ‘barely’ worth the effort to salvage a single 280Ah stripped cell - for a cells with Virgin threads, it would be a showstopper (at least for me).

 

[zzyzx]

In order to use the same size grub screw or bolt (M6 in this case) you do have to drill it larger to accept the helicoil. The helicoil exterior diameter in any instance will be larger than the existing hole/thread size. The interior of the helicoil will be the same size (M6).


You do have tap the hole IF you want to use the same size of bolt/grub screw (M6 in this case). I think you may be able to find a helicoil to fit the existing threads in the terminal (which are M6 in this case) BUT the resulting threaded area will be smaller diameter as a result, and you will the have to use a smaller diameter bolt/grub screw.

In order to do what you describe you would have to find a helicoil that fit the M6 threads that are already there, and then use smaller diameter screws/bolts to affix the busbars.

THANKS for the clarification . . . DRAT.