Using Plunge Or Table Mounted Router For Cutting Cove

How large of a radius are you thinking about? From the picture it looks like it might be a 2 1/2"-3" radius.
Maybe a bit like this, take a lot of passes of 1/8" height til you reach max.
https://www.amazon.com/Router-EnPoi...517805&sr=8-18&keywords=round+nose+router+bit

I would use a table set up, set it to start at the center of board and cut 1/8" high. Then move the fence away to cut max width,( W/O changing height. Then turn end for end and run it through to cut the other side. Then raise the bit 1/8", move the fence forward 1/8", make a pass then end for end do the same , repeat til you as deep as you want.

Or take it to the TS and draw the profile on the oend of the board and set your fence and blade height the cut to the profile and it will be a stairstep halfmoon cut when you are done and you can sand out the stairstep the make a smooth radius.
Herb





Herb

I found a core cutter of 2 inch width at Sommerfeld at about $45. I don't think that is wide enough for a guitar neck. I'm sure you can get larger, but couldn't locate one online just now.

I think that if you use a cove cutting jig, you can produce any width you want and the jig will allow you to make the cut with minimal risk. The Rockler jig has a place to mount a feather board over the blade itself, which means you can use a push stick at the end of the cut. And the price is about $100 at Amazon. https://www.amazon.com/Rockler-Cove...&sr=8-1-spons&keywords=cove+cutting+jig&psc=1

You can make your own for a few bucks using clamps to hold everything in place and push blocks to hold the workpiece down. It looks to be a 18 inch long piece at most, and a knot-free section of 2 by will cut easily.

I use my own jig for this. It's made similar to the one posted by Tom, but probably with less adjustment capability. I also use shop made feather boards and several clamps to hold everything in place on my Unisaw. It would seem a bit scary to use the saw this way, but if you raise the saw blade only a little, maybe 1/8" or less for each pass, it is much like using the table saw the normal way and just about as safe. If you do deeper cuts, then you are looking for trouble. Use your comfort factor to decide how much to remove during each pass, but don't get too brave, until you have used the jig a few times. Always start with the blade below the table, and then work your way up a little for each pass.

There's a guy (Izzy Swan) on YouTube that made a jig for turning bowls on his table saw. He uses a battery powered drill to spin the blank, but the bowl is cut with the wood blank spinning sideways with respect to the spinning saw blade. He uses a second jig and spins the bowl over the blade in a similar manner to hollow it out.

Charley