Here is a quick down and dirty about what it takes to make a dual bit 5" rope.  This is a picture of the finished product for you to be inspired by.

First we need to know a bit about the bits.  You will see here by the illustration that there are 2 bits that complete the full 5" rope. 

That  means there will need to be a 5"  pitch to make a one start rope.  Looking at the blades picture taking the center one away.  Really all you have left is a 2 start rope at 2.5"  spacing.  After those first 2 cuts you will make the center blade cut 1/2 a blade width back,  to center it on a hump.  Got it?  Now you will notice I modified the this rope into a classical twist.  I added another start.  That would mean you would need a 7.5" pitch.  5" for the rope and 2.5" for the ledge and corebox cut.

Lets get started, round off your stock.  Then set the pitch to the 7.5 gears.

Load in 7525 bit and run 2 passes 2.5" apart

Now change over to the 7524 bit and center the point on the edge of the unmilled area.  Plunge about 1/2 way, 2 passes will show you love your equipment.

Move it 2.5" to the right and make another pass

Now set to full depth and run the same two paths. 

Now you can see the full radius and the pointed area that will be our ledge and corebox cut. 

We will use the 7525 bit for this ledge cut.  After all it's handy and the bit almost runs flat at the ends.  Just center it on the point .

Now use the same path with the core box and you will be finished with the router.

And now the fun part, sanding.

This is what the bits look like after a job

Hope you learned something ask questions, I'll answer them as soon as I can.