This is how i make calls when i want to make a bunch in one sitting. I use a mandrel for soft woods and the jaws for large pedestals.
FYI this is not good for all woods ie soft woods or woods that wont hold a thread.
Here is the directions for the Jig
I first mount a piece of pine or scrap wood to the face plate round it and use the drill chuck to make a 5/16 inch hole
I then use a 3/8 tap to make threads
Using a 2inch 3/8-16 bolt thread from the back of the face plate.
Making the call
First I find the center and drill a 5/16 hole in the center
Then i use a 3/8 tap to make a thread
Using a disk jig with the same thread in the center i mark the wood
Here are some jigs
Note when you drill all the holes a put a dowel in the first port hole so the jig does not move, even tho the jig is screwed tightly to the piece it can still move.
Drill all the holes the example happens to be 5/16 inch hole
Attach the piece to the lathe
Make sure you screw it in tight it might look like its off a little but once you tighten it up it will be flush
I like to round the blank but not all the way then just do the bottom and sand it.
You can then unscrew the call and flip it over, screw it in to the lathe and its already centered and ready to go. You might need to trim a little on the outside wall to square it up then you can work on the inside. I then use the Slate jig this is a good time to screw it in the face mark you shoulder then unscrew it.
Then i have a jig to get the correct spacing between the soundboard. I cut it in half to be able to see how far i need to go the outer diameter fits in the slate groove. This Jig has two sides for different depths.
All done Just needs to be sanded and oiled I also like to run a larger bit through the center to get rid of the threads.
I hope you like this post