Hello PMU Artists,
Have you ever noticed the differences  in how a 3 Round liner or shader needle are arranged? Maybe you're tattooing and seeing a different pattern when you switch from brow to brow or you notice a color difference.  Maybe your eyeliner got too thick on the inner part...

Of course this can be one of many "needle influencers" such as your speed, stretch angle depth, or pressure, but for a start, I would recommend to take a close look at your needle arrangement.

Are you leading your needle with 1 needle or 2?
Not only can the needle spacing be unique to each needle manufacturer but the needle arrangement is to consider as well.

 If you're trying to create a very thin line on the inner portion of the eyeliner, or a crisp line for lips it is most helpful to recognize exactly how your needles are configured so you can be precise when tattooing. 

Once you pay attention to this you may find yourself rotating your machine  for those tiny details...