X ends nuts come out

I've been having an issue where suddenly the nut comes out of the x idler end.

It almost seems like the entire system is "over constrained" from bolts holding the motors, and then tension gets relieved the only way it can, with the nut popping out.

Originally the x axis was perfectly level with the bed and the frame, but then when the nut pops out the system "naturally" comes to rest with the left side of the x axis assembly being about 10 mm higher than the right!

Since the nut is press fit only, how do I prevent it from suddenly popping out? How do I resolve this issue in general?

how about a picture?

If its the Z nuts, then your X axis design may be upside down compared with normal machines.... as gravity should hold it in place.

Also ever heard of glue?

Gravity should be holding everything in place, but even so, one end rises up 10 mm above the other side. (x idler side)

I think at least one of the issues was "hole for press fit nut was not tight enough"...which sadly is a very subjective thing.

In my experience, anything press fit will fail and fail quickly.

I'm trying super glue, but if I have to count on the strength of the glue for my printer to work...something is wrong there.

I checked my smooth rods for the z axis, and they are perfectly parallel.

One thing I thought of: I'm using the spiral cut aluminum couplers, and I had the threaded rods flush up against the motor shafts, both pushed in 50% of the way so there is no gap between the motor shaft and the rod.

Perhaps both should only go in a minimal distance, to allow the couplers to flex a lot more?

In addition, what type of metal should be used for the nuts? Does it matter?

As Dust implied - we don't know what your machine looks like so its not clear what "nut" you are talking about.
We assume you are talking about the "nut" on the Z axis. Is that true? Are the "nuts" on the bottom of the X axis ?
The top of the "threaded" Z rods should not be constrained.
Yes its best to have a small gap between the end of the "threaded" Z rod and the motor shaft.
Metal for Z "nuts" doesn't mater.

Name of machine and photo or diagram of problem would be helpful.

Since most printers are made of dissimilar materials, and light to no stress, nuts usually stay put.

If you are seeing a lot of vibration, set the machine on a dampening material such as foam pads, or rubber feet.

CA or loktite or heck white glue, shoudl hold a nut in place against vibration.

Considering all the problems you are having with this machine, I was expecting that you would be the one loosing nuts !
How about letting it self destroy itself ?

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

If it's a prusa i3 clone the x idler is held by a screw into a nut that draws back the idler to put tension on the belt. Is the problem that this screw comes undone? Replace the nut with a nyloc nut. Any nut that's subject to vibration and should not come undone or move by itself should be replaced by a nyloc nut. The Z rods should not be replaced with a nyloc nut as it needs to move the x axis up and down. The steppers will not be able to overcome the friction of the nyloc nut.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]

I used super glue to hold these nuts in place and so far so good.

I also added space inside of the aluminum couplers between the motor shaft and the threaded rod.

If this happens again I'm getting real lead screws.

As an aside: The nut that holds the x idler pulley is a regular nut. I tried a nyloc, but nyloc nuts do not work with the nut trap...it just strips out the nut trap when tightening.

Is it possible to use nut traps with nyloc nuts?

I believe your printer is a Folger Tech 2020. Correct??

I have a Prusa i3 clone and did have a similar problem.
My Z drive motors are at the bottom whereas yours are mounted at the top I believe.

Gravity should hold the carriage in place with the Z drive nuts resting in their respective recess - force or glue should not be needed.
Neither should messing with the spiral-cut adaptors to the motor shaft.

In my case, all was well and then I would look back to my printer to find that the nut on one side was out of the mount as you describe.
A lot of faffing around and I discovered that one of my z drive motors 'stuttered' rather than turning in unison with the other and would then behave itself again leaving the carriage out of true.
Yet more investigations before I discovered that it was one of the connections from one motor onto the RAMPS board - the connectors are a bit flimsy to say the least.
Since I have tightened the connectors and made sure that any vibration cannot affect it, I have had no problem.

Hope this helps.