Hi all.Sorry for my English. I have big problem and i dont know where to find solution. Here is movie.
I got strange noise i 0:07 sec and 0:12-0:28 sec. There is no location where it happend, totaly random. X axis dont move smooth 
i check pulley set screws. Reassembly X carriage, clean amd make some modyfication by Mike like that
What i can do ?
Edit: If i connect with UGS and move x-axis theres all ok. I move it by 500mm right and back, right and back, i dont have that noise… thats normal with move by nema motor ?
Sounds like belt slip to me.
Maybe try disconnecting the wires from the X axis stepper motor and touching them all together to form an induction loop in the motor, this will cause the motor coils to resist manual movement, then see if you can move the gantry and make the belt slip.
You could check for belt slip by making a mark on the pulley attached to the x axis stepper and another mark lined up with it on the cable (pencil should show up on both and will be very easily removable). Then move it till you hear this sound, and then gently move ti back to where the marks should line up. If the marks always line up then you are not likely having belt slip.
This is just electrical resistance to the gantry being moved by hand with the steppers connected. It’s not a big deal. Mine has done this since I got it.
Getting your v-wheels tensioned juuuuuuuuust right will help alleviate some of this, but not all of it, and it will come back sooner or later. Just move the gantry very slowly if you have to move it manually.
I think problem is solved. I reconnect the wire motor cables, tension v-wheels, tension belts, pulley, all washer, screws, clear makerslide and make some modyfication:
A 30 minute x-axis mod to reduce chatter
Modyfication by Mike
And add extra led near spindle 
Make many tests like circles, square, lines and no losing steps, no strange noise from x-carve, always smooth move. I hope thats it Ty guys for sugestions and idea for modyfication
