JB Weld versus Loctite for grubscrews

[fafrd]

I would expect JB Weld on the male thread to mostly get expelled back to the stripped portion, filling it up well. So should be good to repair the partially stripped one (even easier than completely bonding a fully stripped hole.)

If someone was trying to epoxy a stud to a blind threaded hole, I could imagine the vented stud would make it possible. I'd expect thread as the only path for epoxy bleed to cause hydro lock.

So I think you are saying you would only apply JB Weld to the male thread (without a vent hole)?

 

[Gazoo]

The only thing you will be first on is drilling holes through the entire length of your studs, essentially turning them into tiny drinking straws.

I will be commenting shortly.

 

[Bob B]

I'm not sure whether the hole thru the stud is necessary or not .... and I also agree that it is desirable to have a way to hold the stud with a tool while tightening ..... but .... It seems to me that this may make actually increase the overall thread strength. If there is JB weld all around the stud and some in the bottom of the hole .... and some comes up into the hole in the bottom of the stud it would seem like it would be acting kinda like putting rebar into concrete. Stripping the aluminum would have to strip the threads and also shear off the JB weld that is coming up into the hole.
It will definitely prevent hydraulic pressure on the bottom of the hole.

Not sure If it's necessary to go to all that trouble, but there seems to me to be a benefit to doing it. I would add some noalox to the stud as a lubricant when tightening the nut and there should be very little twisting force on the stud. I plan to use a Belleville washer on top to determine the pressure rather than rely on a torque wrench. I think HaldorEE determined that the torque wrench can't be relied on to be accurate.

Just another way to look at it.

 

[noenegdod]

Here is the thought process I worked my way through:

• If you apply to just the male threads, it will seal air in the hole which needs to find its way out. It will either push its way through the epoxy creating voids, if the epoxy seals well enough you will pressurize the blind hole enough deform the bottom of the hole or force it into the cell or there will just be a pocket of high pressure air maintained. The majority of the epoxy will end up on the outside of the hole.
• If you apply it to the female threads the epoxy will get forced into the blind hole ahead of the stud there will also be air trapped that needs to find its way out. See above however as there is a leading edge of epoxy in the hole sealing the end of the stud I think air pressure will be higher
• If you apply it to the bottom of the hole all the air will be forced out as the stud enters and meets the epoxy some will extrude up the threads until its viscosity prevents it from traveling any further, The stud stops threading into the hole and any further attempt to advance the fastener results in rupturing the bottom of the hole. Alternatively, the epoxy fully extrudes through the threads, the stud seats you clean up the overflow. Ideal outcome. Alternatively, insufficient epoxy is applied in hole and threads are not fully bonded
• Vent hole is drilled in stud. Epoxy is applied to female threads and a smudge to the first male thread. Male thread epoxy is deposited on exterior surface of female threads and is smeared along the remaining male threads as twisted into terminal. Epoxy on female threads is pushed into hole as air is exhausted. As the stud approaches the bottom of the hole all air is exhausted and the remaining epoxy is forced up the hole until the stud bottoms.

 

[FilterGuy]

BTW: Long set-time epoxy is much stronger than the 5-min stuff at the big box stores..... but that assumes you have the patience to leave it alone and don't let it move for 6-8 hours.

Also.....you will enevitably get some on the pads of the terminal. Make sure it all gets cleaned off.

 

[FilterGuy]

Here is the thought process I worked my way through:

• If you apply to just the male threads, it will seal air in the hole which needs to find its way out. It will either push its way through the epoxy creating voids, if the epoxy seals well enough you will pressurize the blind hole enough deform the bottom of the hole or force it into the cell or there will just be a pocket of high pressure air maintained. The majority of the epoxy will end up on the outside of the hole.
• If you apply it to the female threads the epoxy will get forced into the blind hole ahead of the stud there will also be air trapped that needs to find its way out. See above however as there is a leading edge of epoxy in the hole sealing the end of the stud I think air pressure will be higher
• If you apply it to the bottom of the hole all the air will be forced out as the stud enters and meets the epoxy some will extrude up the threads until its viscosity prevents it from traveling any further, The stud stops threading into the hole and any further attempt to advance the fastener results in rupturing the bottom of the hole. Alternatively, the epoxy fully extrudes through the threads, the stud seats you clean up the overflow. Ideal outcome. Alternatively, insufficient epoxy is applied in hole and threads are not fully bonded
• Vent hole is drilled in stud. Epoxy is applied to female threads and a smudge to the first male thread. Male thread epoxy is deposited on exterior surface of female threads and is smeared along the remaining male threads as twisted into terminal. Epoxy on female threads is pushed into hole as air is exhausted. As the stud approaches the bottom of the hole all air is exhausted and the remaining epoxy is forced up the hole until the stud bottoms.

Have you successfully drilled a hole through a 20MM long M6 stud? What size bit did you use?

 

[noenegdod]

I'm not sure whether the hole thru the stud is necessary or not .... and I also agree that it is desirable to have a way to hold the stud with a tool while tightening ..... but .... It seems to me that this may make actually increase the overall thread strength. If there is JB weld all around the stud and some in the bottom of the hole .... and some comes up into the hole in the bottom of the stud it would seem like it would be acting kinda like putting rebar into concrete. Stripping the aluminum would have to strip the threads and also shear off the JB weld that is coming up into the hole.
It will definitely prevent hydraulic pressure on the bottom of the hole.

Not sure If it's necessary to go to all that trouble, but there seems to me to be a benefit to doing it. I would add some noalox to the stud as a lubricant when tightening the nut and there should be very little twisting force on the stud. I plan to use a Belleville washer on top to determine the pressure rather than rely on a torque wrench. I think HaldorEE determined that the torque wrench can't be relied on to be accurate.

Just another way to look at it.

I am now planning to use a spring washer of some kind. I saw that in another thread and really liked the idea. Lubricating threads is important and you/he is absolutely correct. Torque wrenches are simply an easy to estimate stretch. When building engines especially when tightening critical fasteners, if you have exposure to both ends of a stud or bolt you use a stretch gauge. You tighten the fastener until you stretch the bolt/ stud to the spec required. Depending on thread condition and lubrication torque is all over the place.

 

[Luthj]

Low viscosity epoxy will move up the threads under pressure, assuming the threads are already stripped. Put some at the bottom of the hole, and a bit on the female side of the threads, and gradually thread the screw in. Don't use 5 minute epoxy though. It could take 5 minutes until you have reached the bottom.

 

[Gazoo]

Hey my friend, I think you may be missing the fact that these are not stripped threads. There is a huge difference between threading a stud into a blind hole and inserting a stud into a clearance hole. The amount of space for extremely viscus excess epoxy to find its way past out past threads is miniscule. I wouldn't bother with a vent hole if I was repairing threads. That said, personally I probably wouldn't repair a stripped out hole. I think I would opt to go up a size and then epoxy the stud in to threads as I am doing.

The hole through the center certainly makes the stud weaker. No question. But everything is relative. In this application ( Epoxied into apparently very soft aluminum) the remaining material of the stud far exceeds the strength of the female threads.

Its obvious you feel Im heading in the wrong direction and thank you for your feed back.

While JB Weld surely has more viscosity than Loctite, I too question if vent holes are necessary although I don't consider it a terrible idea either. I think some are visualizing it to be thicker than it is. In my case I stripped out all the threads, but there were still ribs in the cell terminal where the threads were.

When I inserted the stud it went in easily and I applied a liberal amount of JB Weld with a Q-tip stick to the cells terminals. After applied I noticed some of the JB Weld coming up through the the cells terminals and it kept doing that for about 15 minutes and as I recall I cleaned it off 3 or 4 times. The cure time for the standard JB Weld is 24 hours but I let it sit for 2 days.

 

[noenegdod]

Have you successfully drilled a hole through a 20MM long M6 stud? What size bit did you use?

It really isnt difficult at all. Just go pack a page and you will see some pictures. Cant remember what size I used. Planning to make the hole smaller for the next ones though.

 

[Gazoo]

Here is the thought process I worked my way through:

• If you apply to just the male threads, it will seal air in the hole which needs to find its way out. It will either push its way through the epoxy creating voids, if the epoxy seals well enough you will pressurize the blind hole enough deform the bottom of the hole or force it into the cell or there will just be a pocket of high pressure air maintained. The majority of the epoxy will end up on the outside of the hole.
• If you apply it to the female threads the epoxy will get forced into the blind hole ahead of the stud there will also be air trapped that needs to find its way out. See above however as there is a leading edge of epoxy in the hole sealing the end of the stud I think air pressure will be higher
• If you apply it to the bottom of the hole all the air will be forced out as the stud enters and meets the epoxy some will extrude up the threads until its viscosity prevents it from traveling any further, The stud stops threading into the hole and any further attempt to advance the fastener results in rupturing the bottom of the hole. Alternatively, the epoxy fully extrudes through the threads, the stud seats you clean up the overflow. Ideal outcome. Alternatively, insufficient epoxy is applied in hole and threads are not fully bonded
• Vent hole is drilled in stud. Epoxy is applied to female threads and a smudge to the first male thread. Male thread epoxy is deposited on exterior surface of female threads and is smeared along the remaining male threads as twisted into terminal. Epoxy on female threads is pushed into hole as air is exhausted. As the stud approaches the bottom of the hole all air is exhausted and the remaining epoxy is forced up the hole until the stud bottoms.

I get your points but I don't think there any concerns. The way to make sure is to screw and unscrew a stud several times maybe one or two turns then all the air gaps will be filled.

 

[noenegdod]

While JB Weld surely has more viscosity than Loctite, I too question if vent holes are necessary although I don't consider it a terrible idea either. I think some are visualizing it to be thicker than it is. In my case I stripped out all the threads, but there were still ribs in the cell terminal where the threads were.

When I inserted the stud it went in easily and I applied a liberal amount of JB Weld with a Q-tip stick to the cells terminals. After applied I noticed some of the JB Weld coming up through the the cells terminals and it kept doing that for about 15 minutes and as I recall I cleaned it off 3 or 4 times. The cure time for the standard JB Weld is 24 hours but I let it sit for 2 days.

Water is really thin and flows quite easily through a 1/2" tube. Even 100' of 1/2" tube isnt that bad. 500' is a completely different story. This is what is happening as you are threading the stud in the hole. You are making the passage way longer with each turn (again, remember this is a threaded hole not stripped out. There is a seal called a labyrinth seal and it functions almost exactly like a thread: https://en.wikipedia.org/wiki/Labyr...nth seal is a,the oil lubricating the bearing.

Im not saying the vent hole is required, really dont know if it is for certain. It is the way Im going and in my mind it addresses all the potential issues I have been able to think of ahead of time. Yup, it will take some time. I have thousands of hours into my truck build which this is part of so spending another 1.5 hrs drilling studs to ensure the best possible outcome is a no brainer for me.

 

[Gazoo]

-my grubscrews exhibit some ‘play’ all the way down until they bottom when upward pressure fixes the screw in place. I’d guess there is at least 1/64” of play, so it’ll really come down to whether that is enough space for JB Weld to ooze out through or not.

Yeah mine were fairly sloppy too and some were worse than others. It could be they were not following proper procedures to replace the taps during certain intervals, whatever that may be.

-each of my threaded holes appears to be to a different depth. The + terminal on the cell I tested will thread 5-3/4 turns before it bottoms and measured ~6.5mm to the center of the bottom, while the - terminal bottoms after 4-1/2 turn and measures only ~5.5mm.

I didn't measure but as far as I can tell all of my holes are the same depth. You might want to recheck the depth of the cells terminals and see if they are all the same. I had trouble getting a couple of my studs to screw in all the way.

What this means is that if hydrostatic pressure of any JB Weld below the grubscrew prevents it from threading down to the bottom, the only way to know will be to calibrate the number of turns in advance so you can know how much further you have to go.

That's one way. The other way is to screw the grub screw in until you feel it bottoming out then back off a bit.

 

[ArthurEld]

One small drop of loctite completely fills all of the space and comes out the top when the stud is all the way in.
I assumed JBweld was thicker than loctite too and that is why I didn't think it would work well on holes with threads

 

[Gazoo]

Im not saying the vent hole is required, really dont know if it is for certain. It is the way Im going and in my mind it addresses all the potential issues I have been able to think of ahead of time. Yup, it will take some time. I have thousands of hours into my truck build which this is part of so spending another 1.5 hrs drilling studs to ensure the best possible outcome is a no brainer for me.

I agree and I admire your way of looking at this. But has anyone commenting worked with JB Weld before? It's not terribly thick. I watched many YouTube videos and I did not see anyone using vent holes when repairing a stripped stud. So you will be the first one I know of and this is new territory for all of us. I am looking forward to more from you on this topic and looking forward to your build as well.

 

[noenegdod]

I agree and I admire your way of looking at this. But has anyone commenting worked with JB Weld before? It's not terribly thick. I watched many YouTube videos and I did not see anyone using vent holes when repairing a stripped stud. So you will be the first one I know of and this is new territory for all of us. I am looking forward to more from you on this topic and looking forward to your build as well.

Again, not stripped holes, completely intact threads. I agree completely and wouldnt spend the time drilling holes when fixing a stud into a stripped hole. I have used many types of epoxies including jb weld. And thank you!

 

[Gazoo]

Again, not stripped holes, completely intact threads. I agree completely and wouldnt spend the time drilling holes when fixing a stud into a stripped hole. I have used many types of epoxies including jb weld. And thank you!

Yeah I messed up with that comment...lol. But I still think using JB Weld in new non stripped studs won't be a problem. If someone finds out differently then I will change my way of thinking.

 

[chops728]

I'm just amazed at this conversation -- stud strength -- if the JB Weld will hold --- we are talking about 35 inch lbs -- literally nothing as far as torque goes --- personally I would be putting blue loctite on good threads

 

[FilterGuy]

--- personally I would be putting blue loctite on good threads

There are two conversations intertwingled in this thread.
1) What to do if you have damaged or stripped threads.
2) What to do if you have brand spanking new cells with good threads.

I agree with you that loctite on good threads the very first time you screw in the posts is the right thing to do. Get them in and never take them out. (I would probably use red though). In the past I used a conductive silver epoxy but have since decided it is not worth it.

Unfortunately, as DIYers, as soon as we get the cells we want to play with them...and we do. Unless someone has heard the warning that the SS screws will damage the soft aluminum threads, they end up with damaged or stripped threads. That is exactly what happened to me with the first cells I bought. A lot of others on this thread and other threads have said the same. I am willing to bet that for every one that admits they did it there are several that have not admitted it.

 

[noenegdod]

I'm just amazed at this conversation -- stud strength -- if the JB Weld will hold --- we are talking about 35 inch lbs -- literally nothing as far as torque goes --- personally I would be putting blue loctite on good threads

Only problem with blue loctite is that sometimes it lets go and ruins the threads. Personally, I want as close to a permanent solution as I can get.