Amazing machines! Picked up a 2.5 and a 3.2 and haven't put them down! They do it all with ease. I have a 4mm bearing as well and will give that a try too but so far all is good with the other two strokes. Give works amazing and definitely give a nice response. Honestly the best machines I've ever used over coils and other rotaries! Super light yet still strong and with good balance, the perfect machine!