Nah, no problems as such - I just like to know 1-am i getting the best out of my machines and 2-am i doing any damage by doing whatever on them
I knew there would be backlash - I have not used maximum quality ball-screws and its a jelly-like Bridgeport mill with many decades of abuse under her belt
Below is a picture of my mini-mill, it was built for cutting aluminium parts which have now been moved to the Bridgport, the engraving was a bonus really, the picture below was done on the mini-mill, settings were likely far from correct as it was a while back now. I was surprised how similar the result is, the Bridgeport was slightly better i think most likely due to the mass of the machine.
The mini mill has 20mm HiWin linear guides all round, dual ball screws on Y and single on X and Z, runs on a UC100 controller.
Your engraving machine looks a nice little build, excellent detail work.