I split the quill down the natural groove. I have an old Jo-Jan style calmp that the round end fell off so I use it as my cutting/sanding clamp. I use 2 extras heavy duty paper clips to hold the feather tight. I use the breakaway razor knives to split and trim the quill. Then I use a hand sanding block with 100 grit paper to sand the quill down to look like a commercial ground fletch. I tried the drum sander but it was so fast that it is too easy to burn the quill too deep, I can cut, trim and hand sand a feather in less than 2 minutes.
OBTW, if you have a good size turkey or peacock secondary you can use both sides of the feather. You will essentially get a R/W and a L/W out of it. When you fletch and burn them down you will find them plenty stiff enough for flight feathers.
Of course you can get top $$ for those who insist on primary feathers.
I have used turkey, goose, duck and Peacock wing feathers. Far and away the Peacock is the best flight feather.
I have been waiting for a friend to send me some Swan wing feathers. He got one (legal hunt in Montana) and I would like to see how good they are and how white.