Copper threaded rod shears when appling jam nut?
Copper threaded rod shears when appling jam nut?
(OP)
I have a mechanical question hopefully someone has some experience with. Basically I have a 1/4" copper threaded rod through a panel with a nut and jam nut on both sides containing the rod. one of nuts on each side is pinned with a 1/16" (approx) roll pin. When tightening the jam nut against the pinned nut we run the risk of shearing the copper bar at the point of where the pin hole is. I thought to offset the pin to as far to one side as possible but because copper is so soft I don't know if that will help. I've also considered using a set screw throught the side of the nut but worry that over time and general maintenance it will damage the copper rod.
So my question is, is there another way to accomplish jamming (pinning, locking, etc) the nut without ruining the integrity of the copper rod?
Thanks to all..
So my question is, is there another way to accomplish jamming (pinning, locking, etc) the nut without ruining the integrity of the copper rod?
Thanks to all..





RE: Copper threaded rod shears when appling jam nut?
Loctite
RE: Copper threaded rod shears when appling jam nut?
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RE: Copper threaded rod shears when appling jam nut?
RE: Copper threaded rod shears when appling jam nut?
Mike Halloran
Pembroke Pines, FL, USA
RE: Copper threaded rod shears when appling jam nut?
RE: Copper threaded rod shears when appling jam nut?
RE: Copper threaded rod shears when appling jam nut?
Here's a sketch. The assembly inserts into a 1/2" hole in the panel and although my "jam nut" looks crude it gets the point across. Basically I'm looking for something simple that doesn't deviate from this design much. The panel can't be changed in any way.
I realize that procedurally, torquing the jam nut as "could be" specified is the easiest solution but this is being installed in the field by a tech with a wrench.
Thanks again.
RE: Copper threaded rod shears when appling jam nut?
Ted
RE: Copper threaded rod shears when appling jam nut?
Your current flow path is through the mechanical contact of the threads. If you put Loctite in there you've made a capacitor.
RE: Copper threaded rod shears when appling jam nut?
Mike Halloran
Pembroke Pines, FL, USA
RE: Copper threaded rod shears when appling jam nut?
You could use the same rollpin idea ( similar to using a castellated nut for containment) with a spring lockwasher to the panel to assure a clamp or as others mentioned,nylock
RE: Copper threaded rod shears when appling jam nut?
At any rate, I was taught that an electrical connection that depends on conduction through the faying surfaces of a thread interface is a poor design practice in the first place.
Better to use the threads as intended - to apply force to a terminal and press it directly against a conductor.
RE: Copper threaded rod shears when appling jam nut?
OK,then, solder the one mounting nut to the threaded rod to make the nut an electrically conductive shoulder against which the connection and nut are tightened.
Ted
RE: Copper threaded rod shears when appling jam nut?
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RE: Copper threaded rod shears when appling jam nut?
RE: Copper threaded rod shears when appling jam nut?
I think I'd put two jam nuts against the insulator rather than weaken the through rod with a pin. Bottom line, however, I'd suggest that the 1/4" copper rod is too small... Even 1/4" steel studs are frequently broken off by field people as these small diameters will not stand up to what 'feels right' for a secure connection. Copper, of course will be even more sensitive.
This seems like one of those human factors engineering challenges; the stud may be mechanically and electrically adequate for the task, but unless you can get the field folk to delicately and with a back-up wrench tighten the terminal, the simplest solution may be to just over-size the hardware.
RE: Copper threaded rod shears when appling jam nut?
RE: Copper threaded rod shears when appling jam nut?
mcgyvr, I did take the time to design a very similar setup to the junction block. The trouble is (like anything) the ability to to keep form, fit, function. Althought it might work it won't fit and one that fits won't work.
Thanks again everyone...