Here's two ways I use: 1 make them slightly oversize, glue together then cut to size. 2 make the first one exact then glue slightly oversize pieces to it and use a router with a bearing guided straight bit to trim the excess. With both ways you will have to cut the outside of the three base pieces first before you glue the top piece. Oh, I forgot the lower piece does not get glued, with that one you can temporarily adhere it to the others with double sided carpet tape.

Bill

: Ok, the deed is done - so I'm really asking this after the fact. I cut the
: parts for a plywood coaming yesterday (generally using Tom's
: instructions). It's 3 1/2" rings with a 1/4" coaming lip on top.

: The way that I did it was - I cut the coaming lip first. I then used that as
: the template for the inner-cutout area for the 3 riser rings. I drew the 3
: all at the same time. I cut out the 1st of the 3 rings and used that for
: the outer-cutout area for the remaining 2.

: (Whew, that was a lot to say - I used what I had already cut as templates for
: the others.)

: Anyway, to say that they're not identical is an understatement. They're
: mostly-close, but I really had to take time to figure out what the baloney
: happened for most of them. They are, however, close enough for me - I've
: started epoxying them together and the basering to the boat frame. You can
: see the outer edge in the picture below - I don't have any real good
: pictures of the inside edge.

: My question is - do you have any tips for the next time I go to cut 3 1/2
: identical rings?