Red threadlocker - stronger than torque specs?

I'm thinking about using the red threadlocker (the "permanent" type) on a fastener to avoid flashing off the zinc coating through welding.
An example of the application can be seen in this image:
http://i.imgur.com/YHH7P.jpg
In that image, the nut at the top is welded to the threaded rod, and its purpose is to rotate the threaded up and down to extend/retract the threaded rod against a heavy load (generally, a house structure).
The thread size in my application will be 1.25" x 7 TPI.
Do you think that the red threadlock will hold the nut to the threaded rod when the threaded rod has significant weight bearing down on it?
Jon
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On Thu, 16 Feb 2012 23:04:00 -0800, Jon Danniken wrote:

My thought is that red threadlocker will work just fine, as long as you also drill a 3/8" hole through the nut and rod and put in a good grade of cross-pin.
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jiw

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Two nuts tightened against each other should work well, as long as you remember to turn the lower one for Up and the upper one for Down.
jsw
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On Thu, 16 Feb 2012 23:04:00 -0800, "Jon Danniken"

Why take a chance? Run another nut on that puppy and lock it to the base when you've attained solidity. I hope there's a good grease in that upper pivot point.
P.S: Where are your vapor barrier and borate pesticide treatments? And seal up that cracked foundation, will ya? ;)
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I personally do not see any need for any threadlocker, as there is no vibration or twisting forces that would cause the nut to unscrew.
i

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Well... let's assume he plays piano right over those jacks, and lives 110' from a railroad track.
THEN he needs thread-locker, but the blue stuff will work just fine.
LLoyd
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On 2/17/2012 8:11 AM, Ignoramus23204 wrote:

...
As I read it, he wants to use it to actually raise/lower the column, not lock the column in place.
As another said, for that needs either double-nut or to pin it--threadlock is a "maybe will, maybe won't" depending on how much load is actually put on it in application which is probably not known a priori very closely at all.
--
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dpb wrote:

Yes, thanks, I didn't do a very good job of explaining the purpose of the nut.
The actual nut used in raising and lowering the threaded rod is not visible in the image. The nut that is visible is welded to the threaded rod, and is only used to give you something to put your wrench on to turn the threaded rod.
Jon
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On 2/17/2012 2:52 PM, Jon Danniken wrote:

OK, so what specific nut _are_ you about asking then?
If you're talking about a jamb/locknut after position is fixed, that will hold find w/o anything except a good torque'ing when you've got the column in place. Iggy's right on there in that case...
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Got it. I'd put two nuts locked together at the top to grip and turn the threaded rod and another resting on the hole in the top of the column to support the load. Then pull the wrenches on both the top and support nuts simultaneously in opposite directions to avoid applying a large sideways load that might shift the column.
With a rod that large you could probably get away with machining a square for an open-end wrench on the rod itself. That's what I did on the 3/4-10 track leveling screws here: https://picasaweb.google.com/KB1DAL/HomeMadeMachines#5107453006429714322 The head lifting screws are double-nutted to the cranks and sprockets at the top.
jsw
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xJim Wilkins wrote:

Interesting; I had planned on having the load bear on the top of the threaded rod (which seems to be the way the ones in the image are built) but perhaps it would be better to spread it out on the bearing surface of the nut instead....
Jon
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On Fri, 17 Feb 2012 12:52:51 -0800, "Jon Danniken"

I don't know how well Loctite sticks to zinc but when used properly on steel or stainless steel it grips so well that sometimes the threads willn be torn off before the Loctite fails. I have experienced this. I have contacted the makers of Loctite more than once to ask about specific situations and they were always able to give me an answer about whether what I wanted to do was possible and what compound to use. Eric
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I don't think loc-tite red is listed as permanent. Just as for larger bolts. I break it loose with a wrench whenever I need to.
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    Go for the bearing mount version -- which is also red, IIRC. It will set up better in threads which may be as loose as these 1.25x7 threads may be.
    But an alternative would be a cross hole with a dowel pin in it to keep the nut from turning on the thread.
    Is that thread an Acme thread? I would consider that better than a normal V thread for the task.
    Good Luck         DoN.
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DoN. Nichols wrote:

Yeah, I was kind of surprised how loose the threads were, but everything is in spec so I guess that's just the way it is with larger fasteners. I think I'll drop them a line and see what they say about it, thanks for the suggestion.

Someone else suggested this, but I don't want to weaken the assembly any more than I can get away with.

I couldn't get any tensile strength ratings on ACME threaded fasteners, and the cost was quite a bit more. If I was going to push this assembly to anything approaching load limits I would reconsider, but for now It'll be UNC.
Thanks,
Jon
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On Thu, 16 Feb 2012 23:04:00 -0800, "Jon Danniken"

I don't know if this is anything like you are proposing:
http://www.flickr.com/photos/27683124@N07/6785942879/in/photostream
The double nut at the top has been replaced with a single nut held by Loctite 262 (red threadlocker). I have had no problems so far.
I also use the 680 retaining compound (or rather its Vibratite equivalent) on non-threaded parts and it, too, has been more than satisfactory.
Michael Koblic, Campbell River, BC
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snipped-for-privacy@gmail.com wrote:

That looks to be a similar concept, even if the loadpoint is different. I did consider the double nut approach, but I don't have the room for two nuts, and will just be using one.
After considering red threadlocker vs. welding the nut, I have come across a third possibility, and that is to JB Weld the nut to the threaded rod. It's thick enough to fill in all the gaps between the threads, especially since this is not an assembly which is intended to be threadlocked with a force acting on the fastener.
Using JBWeld would obviously be a permanent solution, but then so would welding (for the most part).
Jon
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Hire a Dutchman to hold it: http://www.roton.com/eng_bul_964.aspx
jsw
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On Mon, 20 Feb 2012 13:48:34 -0800, "Jon Danniken"

Just a caveat:
JB Weld is no stronger than the 680 compound (I have not tested it against the 262). When the JB Weld fails the failure is catastrophic, i.e. the parts are now free to rotate within each other. The 680 fails at a certain point but retains its strength below this point.
In my applications the latter is infinitely preferable.
Michael Koblic, Campbell River, BC
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