JB Weld versus Loctite for grubscrews

[Solarfun4jim]

Yes, that’s what you need to do. So if I am going with 5/8” threaded rod, I will slip in some 3/8” stainless tubing and use 3/8” Belleville washers.

That’s for total ‘range’ of ~8mm where the first washers will need to pass by multiple threads.

This should be much less of a concern with only a single washer compressed to 50% meaning less than a full M6 thread.

When my set screws arrive, I may give this a try...

You are the first i read about the washers sticking on the threads....already ordered mine, but had i known about this, then i might have went with 2mm thick washers instead of 1mm, since my threaded rod is 1mm pitch.
Learn something new every day

 

[fafrd]

You are the first i read about the washers sticking on the threads....already ordered mine, but had i known about this, then i might have went with 2mm thick washers instead of 1mm, since my threaded rod is 1mm pitch.
Learn something new every day

I literally just discovered this yesterday and I’m not yet convinced these washers perform as expected.

From a quick try tightening onto a 4” bolt, one deformed in the threads and a couple look like they flattened and did not spring back.

So all I’m saying is take this concern with a grain of salt and test when your washers come in...

Did you get 1/4” or 5/16” washers?

 

[Solarfun4jim]

I literally just discovered this yesterday and I’m not yet convinced these washers perform as expected.

From a quick try tightening onto a 4” bolt, one deformed in the threads and a couple look like they flattened and did not spring back.

So all I’m saying is take this concern with a grain of salt and test when your washers come in...

Did you get 1/4” or 5/16” washers?

I plan to use my springs from 75% deformation down to 25% deformation...definately dont want them flattened.
I should get my washers tommorow, so the fun starts then.

 

[fafrd]

I plan to use my springs from 75% deformation down to 25% deformation...definately dont want them flattened.
I should get my washers tommorow, so the fun starts then.

Oh, I didn’t flatten mine on purpose. I had 70 in series on a 5” bolt with the last 1” threaded.

When I started to thread down the nut to apply some pressure and check the range, I eventually figured out that something was wrong and took of the last ~10 washers.

The thread on the bold was clearly deformed in one area, as was one of the washers (so it caught in the thread and the ~50inch-lbs of torque I applied was enough to deform both.

There are two flattened washers now but those were probably between the nut and the stuck washer. I wasn’t careful when I took it apart so I’ve lost track of which washer was where.

One explanation for what I experienced is that I first compressed the full range of however many washers were outside the washer stuck in the threads, then forces went beyond 100% as those flattened washers caused the stuck washer and the threads to deform.

The test I really need to do is to (safely/properly) compress a number of washers to ~50% then release and see how close they spring back to original position.

Many of the cheap Belleville washers apparently don’t spring (and so are largely worthless) but I’m not certain that’s what I have yet (these came from Albany Fastener).

 

[Hedges]

Many of the cheap Belleville washers apparently don’t spring (and so are largely worthless) but I’m not certain that’s what I have yet (these came from Albany Fastener).

McMaster lists Belleville washers in high-carbon steel and chrome-vanadium steel.
Bet the cheap sources provide the same shape stamped out of malleable material.

I saw a drawing calling for rolled/annealed copper in flex circuits, but the manufacturer substituted non annealed material. It could only be bent once before the conductors cracked. Probably saved pennies. (Some models may have reached 100M units)

 

[Solarfun4jim]

Oh, I didn’t flatten mine on purpose. I had 70 in series on a 5” bolt with the last 1” threaded.

When I started to thread down the nut to apply some pressure and check the range, I eventually figured out that something was wrong and took of the last ~10 washers.

The thread on the bold was clearly deformed in one area, as was one of the washers (so it caught in the thread and the ~50inch-lbs of torque I applied was enough to deform both.

There are two flattened washers now but those were probably between the nut and the stuck washer. I wasn’t careful when I took it apart so I’ve lost track of which washer was where.

One explanation for what I experienced is that I first compressed the full range of however many washers were outside the washer stuck in the threads, then forces went beyond 100% as those flattened washers caused the stuck washer and the threads to deform.

The test I really need to do is to (safely/properly) compress a number of washers to ~50% then release and see how close they spring back to original position.

Many of the cheap Belleville washers apparently don’t spring (and so are largely worthless) but I’m not certain that’s what I have yet (these came from Albany Fastener).

I read, that so long as you dont flatten them, they spring back. I suppose a lot will depend on the thickness and quality as to how robust they will be???
Would you mind clarifying a basic engineering point for me(need confirmation of my thinking) If the load is 300kgf, and you have six threaded rods, then that would be 50kgf on each rod?

 

[fafrd]

I read, that so long as you dont flatten them, they spring back. I suppose a lot will depend on the thickness and quality as to how robust they will be???
Would you mind clarifying a basic engineering point for me(need confirmation of my thinking) If the load is 300kgf, and you have six threaded rods, then that would be 50kgf on each rod?

Yes, that’s at least one thing I’ve understood. Applying X kgf through N rods translates to X/N kgf of force applied through each road...

 

[Solarfun4jim]

Yes, that’s at least one thing I’ve understood. Applying X kgf through N rods translates to X/N kgf of force applied through each road...

IF...the 300kgf specified in the datasheet is equal to 29.42Nm, then it would seem straight forward to work out the number of washers needed and torquing to give the required results....Will know better once i play with the washers, what problems there might be.
Convert Kilogram Force Centimeters to Newton Meters (kgf cm to Nm) | JustinTOOLs.com

 

[FilterGuy]

@HaldorEE seemed to be having good success with them on his initial threaded rod setup .... but lubrication would probably improve how they work over time.
Maybe something like Noalox could be used as a lube and kill 2 potential problems at the same time.

Carefull folks..... adding things like oil to the mix is a good way of getting a bad connection between the busbar and cell pad.

 

[Bob B]

McMaster lists Belleville washers in high-carbon steel and chrome-vanadium steel.
Bet the cheap sources provide the same shape stamped out of malleable material.

I saw a drawing calling for rolled/annealed copper in flex circuits, but the manufacturer substituted non annealed material. It could only be bent once before the conductors cracked. Probably saved pennies. (Some models may have reached 100M units)

Which of those 2 would be more durable? Durable meaning not loose their specified pressure with repeated flexing.

 

[Bob B]

Carefull folks..... adding things like oil to the mix is a good way of getting a bad connection between the busbar and cell pad.

Well .... aren't we using noalox on the connection points all the time? Haven't heard any negative reports from doing that.

 

[Hedges]

Which of those 2 would be more durable? Durable meaning not loose their specified pressure with repeated flexing.

I'm not a materials guy, can't answer that (quick Google didn't tell me enough either.)
Either would have to be heat treated after forming so they act as springs, don't just plastically deform.

I did find a mention of alloy steels being better for high stress or shock. Might matter for mounting a gun barrel but wouldn't matter for a cell terminal or clamp.

Chrome Vanadium - ASTM A 231 - Spring Wire Properties

Optimum Spring manufactures extension, torsion and compression springs with Chrome Vanadium - ASTM A 231 - Spring Wire Properties

optimumspring.com

 

[cinergi]

If you use loctite, make sure you use primer, first. Some of my loctite'd studs can be turned by hand because I didn't prime them first. The metals we're using aren't "active" metals so loctite won't bond properly without primer.

 

[ArthurEld]

If you use loctite, make sure you use primer, first. Some of my loctite'd studs can be turned by hand because I didn't prime them first. The metals we're using aren't "active" metals so loctite won't bond properly without primer.

I've been reading about primers and activators. The holes absolutely have to be clean minimum.
I'm still researching but I want this to work well and I'm not going to worry about spending an extra $100.

Anaerobic Adhesives is a highly researched subject.

Reliable Plant - Basics on Anaerobic Adhesives and Threadlockers

Loctite "Do it Right" User's Guide

Loctite 263 is recommended for studs

 

[BiduleOhm]

IF...the 300kgf specified in the datasheet is equal to 29.42Nm, then it would seem straight forward to work out the number of washers needed and torquing to give the required results....Will know better once i play with the washers, what problems there might be.
Convert Kilogram Force Centimeters to Newton Meters (kgf cm to Nm) | JustinTOOLs.com

No, they are kgf, not kgf.cm

kgf is force unit, not a torque unit.

 

[BiduleOhm]

Maybe they are scrubbing off high spots. Because clamping force wasn't enough to flatten them?
Wonder if spring backed contacts would perform better. We see those in some lower current board to wire connectors, but not high current like these.
You know those springs people are using to clamp packs ...

Root cause of this problem appears to be resellers of "B" grade cells "engineering" a solution for hobbyists that doesn't involve aluminum welding.
It passed a quick bench test. Good enough to ship!

In the case of the threaded rods, there could be as much as 2MM deflection with just 4 cells in series .... and it is necessary to have a number of them stacked in series ....so, catching on the threads is a greater possibility.

It may only require 1 washer on the cell terminal and any deflection will be minute .... so, it doesn't seem likely to be a problem there.

Belleville washers for keeping busbars on cells terminals?

So, I saw the thread talking about using belleville washers instead of springs for cell compression (NB: I prefer the springs for that as otherwise you'll need to stack a lot of washers to have a low enough k and high enough usable travel) and posting about busbars on another thread when I had...

diysolarforum.com

 

[BiduleOhm]

Sounds like a cautionary tale I should probably look into - do you have a link to that thread?

Short Circuited my 48V 120Ah Build (I'm fine)

Firstly, I'm fine - was wearing safety glasses and gloves at the time and the top of the pack was covered - I do need some new underwear though. In short (no pun intended) I spent the past 3 weeks building my 120Ah 48V pack ever so carefully and managed to short it while hooking the finalized...

diysolarforum.com

 

[ArthurEld]

No, they are kgf, not kgf.cm

kgf is force unit, not a torque unit.

but 12 inch pounds = 300 kgf approximately
Distance between screws plays a part too.
My observation is that 5 - 15 inch pounds when cells are near full charge will keep the baby bump under control.
It also removes all gaps between cells after a full cycle or two.

 

[BiduleOhm]

but 12 inch pounds = 300 kgf approximately

If you're talking about the force a bolt will exert when torqued at that value then it doesn't means much if you don't specify what bolt you're using.

 

[ArthurEld]

If you're talking about the force a bolt will exert when torqued at that value then it doesn't means much if you don't specify what bolt you're using.

Number of cells in the row makes a difference too but about 10 inch pounds at full charge seems to work fine. The cells expand and contract and are forced to make the best use of the available space.
My rods are 3/8"