Double Locking Nuts?
Double Locking Nuts?
(OP)
Silly question.....say you have a threaded rod hanger connection in which a threaded rod is supported by a glulam beam. The glulam beam would have a vertical hole drilled thru the CL of the beam width, the rod would be passed through and then hung with a nut and washer on top of the beam, (and probably a nut and washer below the beam to prevent upwards movement).
To prevent the rod from working itself loose, I was going to call up a double nut above and below the glulam. This would "lock" the connection right? I seem to recall that when you thread a single nut onto a threaded rod, tighten it to make the connection and then put a second nut and tighten it up snug to the first nut, the second nut would prevent the first nut from coming loose since they would tighten against each other???? I can't really visualize it in my head...maybe I should try it out for real!
To prevent the rod from working itself loose, I was going to call up a double nut above and below the glulam. This would "lock" the connection right? I seem to recall that when you thread a single nut onto a threaded rod, tighten it to make the connection and then put a second nut and tighten it up snug to the first nut, the second nut would prevent the first nut from coming loose since they would tighten against each other???? I can't really visualize it in my head...maybe I should try it out for real!






RE: Double Locking Nuts?
I would agree that the double nut will hold together and hold well, but I cannot quantify this holding force sufficiently to give an engineered value - off the top of my head.
Will the rod be subject to cyclic loading? I think there is a world of parameters to be considered. That said, I have used similar details used to suspend conduit, duct work, and a thousand other things that would not be considered structural.
Daniel
RE: Double Locking Nuts?
As an alternate, perhaps you could consider using a chemical locking compound, such as "Loctite" on each (single) nut. It comes is various strengths, including one that is effectively permanent.
RE: Double Locking Nuts?
akastud
RE: Double Locking Nuts?
1. I used jam nuts (mentioned by SlideRuleEra
2. Double nuts
3. Upset the threads so that the nut would not back up
4. Cotter pins
Each method has its proper application. Keep in mind maintenance and future re-work because some of these methods are permanent once installed.
Good luck
RE: Double Locking Nuts?
RE: Double Locking Nuts?
Thanks for all the helpful posts....once again I am impressed by the depth of knowledge available out there!
RE: Double Locking Nuts?
At any rate, all the threaded rods were either double nutted or had the threads compromised in some way to preclude loosening. The only time I used a chemical locking agent was on the SS/glass canopy at the MOCA in downtown L.A. where the rods were double nutted AND chem-locked.
Rod
RE: Double Locking Nuts?
The glulams are actually 5 inches wide by 6 inches deep, framing between glulam trusses, and for appearance reasons the architect doesn't want to see a steel bolted plate on the side of the glulams. The rods are supporting lights for a gymnasium.
RE: Double Locking Nuts?
RE: Double Locking Nuts?
RE: Double Locking Nuts?
We always use ANCO locking nuts for structural applications. The toggle pin bites into the threaded rod or bolt preventing it from backing off.
See at http://www.locknuts.com/pn-loc.html