# Control limits in $\bar{x}$ and R chart

I am learning a Quality Control course and in theory part I don't understand calculating the control limits for $\bar{x}$ and R chart.I want to know, say when I calculate the R chart control limits no points plot outside the control limit.And therefore using this $\bar{R}$ values I can then go to calculate $\bar{x}$ chart control limits.In that say 2 sample values are plotted outside the control limits and in each of these suppose an assignable cause was found.Therefore we have to remove this point and recalculate control limits for $\bar{x}$ chart.My question is do I have to recalculate the R chart control limits also.Because now in $\bar{x}$ chart 2 samples are removed.Or do I use the earlier $\bar{R}$value and use removing the two samples only recalculate $\bar{x}$?

Also say there's a pattern is present like a cycle or a shift in process level.Even if all the points lie inside the control limit with the presence of a pattern does it indicate that the process is out of control?Or is the process in control, but some factor affects to shift the process level?