Danny / all
I thought I would post how I machined my bed wood to have the recess for the offset washers and get a near perfect result.
Short story- use hole saw in scrap wood as a guide for a router bit.
Long story
1. Drill the hole for the carriage bolt in the correct location on your bedwood.
2. Made a jig for the washer recess:
scrap piece of 3/4 wood 4" x 12"- approx
Find a hole saw with the correct size for the washer
Drill scrap wood / jig with the hole saw. Exact location is not critical just centered in the jig.
back to the bedwood use the washer to align with the bolt hole drilled in the wood and use a pencil to trace the outline of the washer. Note the washers are eccentrics so I made sure to orient all the outlines of the washer on the wood with the eccentric facing the same direction.
Use the jig and clamp it to the bed wood, aligning the whole in the jig with the pencil outlines. Clamp the jig to the bed wood.
Use a router with flush cut router bit with guide bearing to use the jig as a perfect circle guide.
https://www.amazon.com/Freud-Bearing...rds=router+bit
Of course you have to set the depth you want.
So this might be over kill but it took only a few minutes to make the jig and I had perfectly routed round washer recesses.