Replies

1. 
   user-148830 | Jul 16, 2008 12:05am | #1

   I believe I would make the center indent on the lathe. Sure to be round.

   If you have no lathe, then I'd carefully make a template with a scroll saw and then sand with a drum sander to your marked out line. Make the template oversize and rout to depth using a template guide.

1. 
   actuary | Jul 16, 2008 12:46am | #2

   Thanks, Gary.
   I don't have a lathe so I may have to go with the template approach. But what do you think of using a circle cutting jig for a router (Jasper J400) and just going down 1/8 inch? That'll certainly give me precision and should be pretty fast.

1. 
   saschafer | Jul 16, 2008 06:09am | #3

   You can get router bits called "dish carving" bits. They have a radiused end, so you get a nice rounded corner on the inside of the lip.-Steve

1. 
   actuary | Jul 16, 2008 02:58pm | #4

   Thanks, Steve, that would be a nice finishing touch. I still need to work through the basic problem of removing the material from the center.

1. 
   saschafer | Jul 16, 2008 09:16pm | #5

   I would do things in this order:

   Use the circle-cutting jig with a 1/4" straight bit to cut out the blanks.

   Build a jig that will hold the blanks firmly in place. For example, say the OD of your coasters is 4-1/2". Take two pieces of 3/4" plywood, drill a 1" hole in one, and use the circle cutting jig to cut a 4-1/2" hole in the other. Glue the two pieces together. Now you have a nice little cavity for your blanks. Use some high-quality carpet tape to hold the blanks in place, and use the 1" hole to push the blanks out when you're done.

   Insert the blanks into the jig and use the dish-carving bit with the circle-cutting jig (and the same center hole) to cut the perimeter portion of the coaster. Don't forget that you'll have to make an adjustment for the circle radius since the dish-carving bit is larger in diameter than what the jig is calibrated for.

   Remove the jig's centering pin and carve out the center of the depression freehand. The combination of the circle-cutting jig's flat baseplate and the top surface of the blank-holding jig should allow you to get a nice, smooth surface.

   -Steve

2. 
   actuary | Jul 17, 2008 05:24am | #6

   Very clever approach, Steve. If only the shape of the outside part of the coaster were round...(I never mentioned that it wasn't). This discussion has been very helpful and I think I know how to solve the problem. I did buy the circle cutting jig today and tried out just routing a few 4 inch circles in a rectangular board to a depth of 1/8 inch with a straight bit, then using the router free hand to clean up the circle's insides. (I'm also going to try it with the dish carving bit.) My next step would be to cut out a 5 inch square around the circle and just shape the coaster with a sander.
   I really appreciate the back and forth discussion.