Juki LU562 grinding noise

[RyderB]

Cleaned out the machine and heavily oiled everything. Making a grinding noise near the gears and fork. Doesn’t happen at slow speeds but then starts around 500rpm and stops after 1200 ish. I can’t tell if it’s a worn out sound or the gears maybe off? Idk, had a similar thing with a consew 226. Any suggestions? The feed bar slide fork has slight play up and down. 

 

 

[friquant]

Call off the coffee mill! 

Wow that's quite the noise. Definitely not just a hum. Doesn't sound like gears assembled with different teeth lining up either. Interesting that it starts and stops at certain speeds.

I would start removing parts (or at least loosen/disable) until it doesn't make that sound anymore. It's hard to pinpoint a location when they are all connected together and moving at high speed. 

First I would remove the needle, so that it doesn't strike the feed dog after we loosen it up. (Keep track of your needle screw though, they can wander off when running a machine with no needle.) Then I would loosen the clamp on the feed shaft, such that there is no more horizontal feed dog motion. Then remove the U-shaped piece that goes provides the vertical feed movement.

If that doesn't clear the sound, I would mark one tooth on each mating gear for the hook (so you can assemble the same way later), then remove the hook and the vertical hook gear. Make note of how many thrust washers come out, and where they were stacked.

If that clears the sound, you might try putting the hook back in but without the latch opener elliptical mechanism.

With anything you remove, make certain that there is no chance of anything binding, and turn over several times by hand before adding power. Wouldn't want something to slip and break.