@Syko_Symatic ok! I sorted it. resonance be gone
I added an additional linear rail (yes I have a few lying around), had a precision grade one from misumi, modified the carriage to suit, bam! Quiet!
Probably need to do the input shaping again to make it even better but the difference now is night and day!
@oliof thanks for the information! How would I make sure one of the points is aligned with my centre point? Is it just using the math and dividing the mesh correctly?
I have used mesh levelling for years but I have noticed a certain issue. I probe the bed (in the centre) then run the mesh levelling, but I’ve noticed that none of the points are ever 0 or near 0, surely the height should be close to zero when near the probes point for Z0?
For example, sometimes all measurements will be over 0, this shouldn’t be possible should it?
Do I have something configured wrong, perhaps a macro or something??
@Syko_Symatic ok! I sorted it. resonance be gone
I added an additional linear rail (yes I have a few lying around), had a precision grade one from misumi, modified the carriage to suit, bam! Quiet!
Probably need to do the input shaping again to make it even better but the difference now is night and day!
@Phaedrux it seems to appear mainly towards the middle of the X axis. I have stripped it back down to the frame re-squared again and checked everything moves nicely (it does). As soon as I load it up with the belts the resonance starts to appear again. I have found that it tends to disappear around the 70-80mm/s speed. But between 30-60mm/s it’s pretty bad.
I added some more fixings to the x rail to make sure it was definitely fixed down. Added an additional cross-brace to stiffen the frame a bit more.
I started with 800ma and move up to 1200ma in 100ma increments and down to 400ma but no change.
Tried 0.9 deg motors, big nope with that one! Increased the vibrations massively.
Currently at 16x with Interpolation. Tried up to 128x with no change.
Hopefully I haven’t missed anything you mentioned, can’t see the comment while I reply 
@Syko_Symatic tried switching to 0.9 motors and it made it worse. Seems to be resonance on the X axis. I have been testing it with no hot end mounted and the vibration is still there. Pulled the frame apart and rebuilt it, problem still exists.
Still can’t think of a solution! 
As the title states really!
I’ve tried tightening/loosening the belts, I’ve check the frame squareness, rebuilt the carriage, re-printed and beefed up all the parts, changed all the pulleys and their posts, tightened everything, greased the bearing blocks, changed motor currents, changed micro stepping, all to no avail.
Struggling with this one. I’ve redesigned everything, it’s very similar to the parts for a Voron, in an attempt to stabilise the X axis if that was the problem but nope.
Any help would really be appreciated.
No going to lie, it’s breaking me.
Jammed some paper in between the looser end on the worm gear and the bearing and it seems to have helped. I have ordered a new nimble (as they have a slightly improved version now) so maybe I need to get a replacement worm gear? I will have to measure it first and see if it was manufactured incorrectly.
@damianm reducing the extruder acceleration to 1000 did wonders to be honest. I will have to check a few other slicer settings and esteps to see if I can improve on the finish I am currently getting.
It's good but now as good as I got from it on my previous printer.
Spoke quickly to Brian from Zesty Tech over email. He suggested a few things which have improved the quality but still not quite there 100%. May be having a call with him tomorrow.
One thing I have mentioned to him though, the worm gear seems much looser in the bearing on one end, I am not sure if this is intentional but may be an issue?
If anyone can suggest anything to improve this result further I am all ears....
@phaedrux diagonals, yes, circles no.
With the nimble what could actually cause that eccentricity?