Need help with a stubborn NUT!!

[dadburn1]

Try using a pair of Vicegrips with some leather, rubber or other material to protect the shaft, Grip it close to the threads. Or thread the locknut on another bolt with the same thread size, Then it will go on easier.

 

[swines]

Go to the McMaster Carr website McMaster-Carr.

Use the "Find" function and put in "shaft collar." An entire page will come up with different kinds of shaft collars - with at least 6 different kinds of split shaft collars. Pick the type you think will work best - order one or two.

They're relatively inexpensive given you don't want to damage the shaft and you can spend hours trying to make or rig something. McMaster gets things to me in 2-3 days regularly on small items. If you need it really fast, pay extra for overnight shipping.

Or, as suggested previously, take a piece of wood that is large enough to make your own collar for the shaft. Drill the hole, cut in two, and clamp around the shaft.

 

[Dusty]

Spoke to the manufacturer yesterday and they said to put a pipe wrench on the section of the threads that isn't used and to tighten that way holding the shaft from turning. I tried this, but the nut still refused to go on any further. I now believe that either the nut or the threads on the shaft are defective. Tomorrow I will have a new nut and hopefully it will go on without any problems. If not, they said that they will send me another cylinder. Dusty

 

[sandman2234]

I hate problems that end up getting the manufacturer involved with sending replacement parts. Probably due to the fact that if they can't do the quality control work on a thread, what makes me think they can handle me under a lift?
Probably not true, but it does give you something to think about!
David from jax

 

[Dusty]

I will say that they have been very good about dealing with any question or difficulty that I have encountered. As for the cylinder, I doubt that they are the OEM of that part, but probably just buy them from another source. I did ask if it were a USA made part, and the answer was yes. I checked the thread diameter difference between the part where the nut goes on and where it stops, and the difference is 4 thousands of an inch.

 

[JoeL4330]

Were you ever able to run a non-locking nut down all the threads? If not, then it's surely the threads at fault. My original suggestion, to run a die down first and then grind/file wrench-flats on the end might not easily work because you wouldn't be able to run the die down, either, without the wrench flats (which would be my preferred solution in the final analysis, if I had to work with this particular part.)

As I recall, the cylinder and the threads were chromium plated, and I would guess they cut the threads first and then plated ...a little too much, in your case. Note that some machinist's dies have some adjustment--they have a single split and an adjustment screw and can cut (or, in your case clean up slightly oversized threads (you can cut undersized threads, but that would lessen the effect of the locking nut so, not a good idea). If it is the plating, which is quite hard, it will be **** on a die, but there would be no other way to fix this one ...somehow, you have to thread to spec, or get a new part.

If, on the other hand a non-locking nut ran down, then I would look for a new locking nut, of course ...and, in the interim, use two "jammed" nuts.

 

[Dusty]

Possibly I wasn't clear enough on the description. I was able to get the original locking nut, that has a round collar of nylon at the end of it, about 3/4 of the way down the shaft. At this point, it wouldn't go on any further, and it was a fight to get it down this far. I then held the shaft with a pipe wrench on a part that wouldn't do any harm to the operation of the cylinder, and tried to tighten it further. I got between 1/2 and 3/4 of a turn additional, and then no more. I then backed the nut off about 1 turn with the wrench, and then it came off with only my fingers. I tried a new nut, of the same type and it would screw on as far as the old one, and no more. This was also finger tight. I measured the diameter of the threads and found that there is a .0004 difference in hight of where the nut will go on and where it stops. I have yet to find a thread chaser or a die to fit this to try to clean it up and remove the .0004 difference. I don't even know if a thread chaser will do this. I have not tried a thread file on the shaft. I figured that it will be too hard of a metal for the file to cut. When I talked to the lift manufacturer, they said that they normally will thread on by hand up to the nylon lock area and then you use a impact wrench to go the rest of the way. They also said that I need to have at minimum 1/4" of rod sticking out of the end of the nut for the cables to be properly set. This nut holds the cable locking assembly and it is part of the cable slack adjustment process, so the nut has to be able to be adjusted without too much hassle. I am still open to suggestions. I believe that the original nut acted like a die and "recut" the threads at the front end of the cylinder. I was also thinking of cutting a single slice through the original nut and try running that on the shaft a few times and see if it might just "wear" the threads down a little, or enough to where the new nut will work without a problem. I can't use the double lock nut method on this. It has to be used as designed.
Dusty

 

[JoeL4330]

I understand better, but you said something disturbing ...you need the nylock nut to function as designed ...but, after you ran it down as far as you could, you could back it off with your fingers ...and, you could run the next (nylock?) down to the impasse with just finger pressure ...that means that the lock nut ain't lockin' anymore, yes/no? So, it is not going to fulfill its mission, if I understand correctly

 

[dqdave1]

Sounds like bad threads; run a die down it with cutting oil if possible. Even if the shaft had been chromed, a die will clean up the threads. Then use a new nylock nut.

 

[LetsRoll]

Sounds like bad threads; run a die down it with cutting oil if possible. Even if the shaft had been chromed, a die will clean up the threads. Then use a new nylock nut.

I agree. I had the same problem with my two post lift that I got from Rotary. Just run a die down it and use some anti-seize lub on the threads to keep them from rusting since the die will cut the chrome off the threads. As a matter of fact, I had to do both side of my two post lift. By the way, .004 doesn't look/sound like allot, but when your dealing with tight tolerance here, .004 is allot (chrome or metal).