I like this way but takes longer.
![dunno :dunno:](https://www.tradgang.com/tgsmf/Smileys/tg/dunno.gif)
I do it all the time.
Here are the bits for fiberglass. They are carbide and coated.
![](https://i.imgur.com/5M16Nw5.jpg)
I start at the edge sander
![](https://i.imgur.com/kETYWCR.jpg)
Drill press chuck is up all the way, I crank the table up for depth of cut.
Your riser needs to be full width and flat so you can slide it around on the table
![](https://i.imgur.com/js8NaFq.jpg)
![](https://i.imgur.com/LFSLF7h.jpg)
after doing it this way I noticed the shank on the bit rubs the shelf above the cutting teeth so I made a pattern/rub collar to get a nice finish and shape. I don't have a picture of it.
![](https://i.imgur.com/UB2cX5W.jpg)
Rub collar has this curve for the shelf
![](https://i.imgur.com/6VbOlkH.jpg)