I have noticed my low cost Alunar 3D printer’s performance is getting better with age. The more I run the printer the better the output becomes.

That tells me the linear bearings and belt stiffness are “wearing” into a smoother operation. I have been using a little very light machine oil only very occasionally on the bearing rods.

Some of it is probably due to having all the speeds and feeds proper too. I do not slam my axis movements around like I see in some user videos. I would like to have easy access to the ramping settings and perhaps I could squeeze a bit more smooth performance. Not a high priority at the moment. I have lots of time.

The surface finish is still not spectacular as the slicing layers are definitely still visible. A little post process finish like sanding or solvent vapor would smooth things up and a coat of paint would create a very acceptable product.

The complaint if it should be considered a complaint, is really just the fresh off the printer surface ridges.

What is improving are the linear waves in the horizontal direction. The layers are vertical imperfections. The horizontal distortion are much like grooves in a vinyl music record. They are caused by machine vibration and I believe sound recording. Sound is created by vibration so the connection is obvious when extruding a plastic filament that progresses as a function of time or speed. Just like a needle in a record groove.

I have discovered and corrected sympathetic and/or harmonic vibration of the drive belts at certain stepping frequencies (speed). I could hear the "buzz" and observe high amplitude belt vibrations. Shifting the "normal" print speed a few mm/sec eliminates the vibration and the amplitude of the waviness in the extruded plastic. It's good to be observant. 

Yep, the machine is running smoother and quieter.