Thanks for the suggestion. I have plans for one now! I'm actually going to do a longworth chuck, using 8 bolts, and use 8 more in between the other holes as permanent hole locations, without the router-arcs---roughly 3/4" in from the outside, so that I can put different circles on top of the thick bottom longworth plates, and interchange discs of different sizes if I need to. I see sites with people using "disposable" jam chucks & the like & just can't bring myself to make something I'm just going to put in the firewood pile after a couple uses, or even just one. I really have just been "bitten" hard by the woodworking bug in the last few years, but I have jigs from plexiglas fabrications from years ago that I can't throw away! Jigs are great; build them right & "modifiable" and you have something you can use in the future....
Thanks for the comments, BTW. I used a thin/med mix to stablilize cracks, and the heptane? catalyst spray accelerator. I have another bowl that isn't finished yet that has a crack filled with epoxy resin that I used an epoxy pigment in---I'll use coffee when it runs out, or sooner. Its extremely messy, and NOT a paste form like it says on the jar, FYI. Its made by system three adhesives. Granted, it really works great, but I got a nice half dollar sized black epoxy stain on my BRAND NEW CARHARTT PANTS!! grumble grumble curse curse. Damn stuff is runny as all getout, and states its a paste on the jar. The second I opened it, carefully...it ran all over from the lid onto my pants. Oh well. guess I just can't wear them out to dinner anymore.