AnyCubic Predator - Loose Carriage Rattle Fixed

I had noticed since the first print that there was a rattle from one of the carriages, and the occasional click or banging noise was fine, but when it was doing high speed infill and going back and forth on a short distance the noise was completely unacceptable.

You can here what is sounds like in this short clip.

I decided enough was enough, and needed to get it fixed.

Having had a look in the manual, there was nothing about adjusting the rollers, so I turned to ask the question in the Facebook Anycubic Predator Group.  I had a feeling I needed to remove the rail and then remove the carriage to adjust, but just wanted to make sure before taking things to bits randomly.

NOTE (thanks for the reminder Kris Waclawski) : Make sure you have tried to adjust the eccentric nuts first using the supplied spanner. You should be able to make 'normal' adjustments using this method without having to disassemble anything. For whatever reasons it was only after I had gone through the steps below, did I get a good fit. Maybe something was stuck or not rotating correctly...anyhow fixed now!

John Chrapkowski shared a link to a GitHub posting https://github.com/skellatore/anycubic-predator on how to deal with the repair. I checked it out, and it was pretty much as I thought.

So first up was to unplug, remove the SD card and flip it onto the side so the rattling rail was at the top.

Next was to undo the arms and spring to free off the rattling carriage.

Unscrew the rail bottom 4 bolts and top 4 bolts. disconnect the stepper cable. Lift off the rail assembly.

Next I used the tweezers that came with the printer, so scribe a line at the top of the tension bar and the roller bar. This would give me a good idea where to re-position them back to. I didn't want to mess with the positioning of the stepper motor at the other end.

Remove the 6 bolts holding the tension bar and the roller bar. Carefully remove the belt off the roller. Remove the tension bar and roller bar. 

Remove the 2 rubber feet from the bottom of the rail.

 Slide out the carriage from the rail.

You may want to remove the bar that holds the belt by removing the two bolts. You may have to try the carriage into the rail many times until it is the correct tightness, so removing the belt reduces the chance of damage.

Now you adjust the roller tightness, it is just trial and error. Suggest do one roller at a time, and keep retrying the fit.

Once satisfied with the fit, rebuild the rail. Make sure you have no twists in the belt. Don't forget to re-check the belt tension. Make sure the carriage runs smoothly back and forth the full length of the rail.

You can hear the difference after adjusting, compared to the clip at the beginning.

Enjoy the peace now, it may also help with any odd marks that may appear in the prints (although I didn't experience any).