How does the K-Factor table work in SWX?

How can I make SWX use an excell formula that my shop uses for K-Factor calculation?

Formula we use is:

(MT x 3) + (R x .435) = K Factor

Where MT is Material Thickness

R is Radius

.435 is a constant I was always told to use.

The problem I'm having is that the flat pattern length (or developed length?) I'm getting in SWX is different to what I'm getting on paper (manually adding flange lengths and deducting one K factor for each bend) when I use the K-Factor that I calculate. So, is there a way to make it so SWX will end up at the same flat length I get on paper when I use the K-factor I come up with?

I'm not the best with sheet metal, still learning. But basically, I need to be able to make accurate flat patterns that are comparable to what we're getting on paper, vs solidworks generated flat patterns. We use an excell formula that utilizes the formula mentioned above, in which we just enter the Material thickness, the Inside Bend Radius and the Angle that we're bending too, and it kicks out the K-Factor. Is it even possible to link an excell spreadsheet like that into swx so that it utilizes that formula and makes it so the flat patterns come out to what I'd get on paper?

See the attached part. To my math on paper, the flat length should be 16.175"

Solidworks, using the same K-Factor of .178, is coming up with a flat length of 16.472"

Or is there a better, easier way to be doing this so that I can just draw parts in SWX and the flats will be correct without having to have one of the old-timers here at the shop hand draw a flat pattern to double check it? Once they saw that there was a disparity between SWX flats and the flats they've been getting drawn by hand (using the same k-factor) they wanted to stop using SWX.