Fiber Laser Marking Machine,Metal Laser Engraver Machine 30W Engraving Machine Raycus Laser Marker Desktop,Metal Carving

I bought the 50w version with the 85mm rotary. laser works fine on flat items, but when you use the rotary, it stops showing the "lighted" preview even on flat marking. After using the rotary for awhile, the focus shows that it is out and the laser stops firing. if all i was doing was flat part marking or business cards it would be fine, but i need to engrave cups that are stainless or powder coated and can't have the machine stop firing after an hour of use......i still have not figured out how to get to fire again after it stops working....i did notice that changing the split size sometimes gets it to fire again, but it is hit and miss. not sure if it is a driver problem or firmware, but it does not function the way that it should....and spending 7k it should work flawlessly.