I'm working off of the SPC manual. Its the most resent edition, but it still has all the calculations based on 5.15 (99%) instead of 6 (99.75%)

I'm trying to calculate the new K2 / K3 values based on 6 sigma, and I'm getting stuck. They are all suppose to be based on the d2* values which are off of the D3 table.

Here is the problem there are no numbers under D3 for the first 6 samples, and the numbers come out strange with higher group numbers.

I reversed the formula of the old calculations if 5.15/d2* = 3.65 for 2 parts, then the number used to get there would be 5.15/3.65 = 1.411. The problem is that number is no where on the chart.

How is this number actually created.

I found a d2* chart in appendix C of the MSA 3rd edition book. thanks

Thanks,