Syil X3 mill - about 2 years old, not a lot of time on it.
It had to sit for about 6 months while other things were going crazy around here. Finally got back to using it, and I wasn't able to get the speeds I usually was able to get out of it, mostly in the Y direction.
What was happening is that when I was using my old speeds that I had in Mach3 (about 30 ipm w/ 2 i/s/s acceleration) occasionally the stepper motor would make what would sound like a ratcheting noise, particularly towards the end of travel when driving the table towards the column. When the ratcheting noise would happen, the table itself would stop moving. If I would slow it way down, the noise would not happen.
I'm able to get about 60 ipm w/ 4 i/s/s acceleration on the X axis, and 45 ipm w/ 2 i/s/s acceleration without any noise or stuttering issues.
I took the machine apart, checked all the ways and cleaned them up, removed any bumps or imperfections with some 600 grit, cleaned the gibs, and then reassembled using a light coat of grease on all the contact surfaces. This definitely helped with the speeds, but the Y axis is still experiencing the stuttering and noise every once in a while. I'm starting to think that the motor current might need to be adjusted, but wanted to check here for any advice prior to doing anything like that. The drivers are set at the factory, apparently, and I would like to avoid messing with them if there's other fixes that you guys can recommend prior to going out and buying a DC amp meter.
From your description it does sound like the gibs are out of place and/or need adjusting.
Step 1: Lose the Y gib screws about 2 turns. Test your rapids again.
Step 2: If that does not work, move the X motor to the Y axis -- do not touch the electronics or the cabling just unscrew it from X and screw it in Y. Go back to mach3 and jog in X -- since the whole thing is now attached to Y that is the axis which will move. Do you continue to have the problem. If you do you the issue is mechanical.
I'm getting 170 IPM in XY with the original Syil's steppers on the SX3.
EDIT: Use way oil (Mobil Vactra #2) on the ways, not grease.