Here is (shortly) what I did to get an acceptable backlash of about. 0,033mm to 0,045mm.
On my machine, the excentric bolts were way too tight. Now, I can slip-move the V-wheels (without moving the carriage) if I apply about the same strenght as if I would open a plastic pepsi bottle. (I know it’s not very precise but I have nothing to measure this kind of movement).
The drawback is that I have to re-tight them often, as vibration looses them quickly. I’ll try to find some lock-tite like stuff that would block the set and can be easily broken to readjust. This too much tightness was causing the mecanisme to loose about. 0.15mm on direction change. This works very well for very light work (I’m engraving PCBs) I don’t know what this “slack” will cause when I’ll try tougher works like cutting wook or aluminum. probably
I also realised, using my microscope to measure movement lengfht per step, that each step did not move the same len. This was solved by raising current with the potentiometers on the X and Y axis (also did on the Z, although it was moving fine) They were originally set to 11 o-clock. They are now set to 2 o-clock. Be sure to have some cooling on the motor drivers (fan or heatsink) as more current to the motors means more heat.
Hope my english is understandable. Feel free to ask questions if unclear.
Vive la France (et le Quebec)