After a bad week spent in Vermont working, I got back to important things in the shop. The second D1-4 backing plate, back ordered before, for my 8" Bison 3 jaw chuck arrived, and I got it installed today. as I bought the chuck used, I found the mounting holes for back mounting were stripped or mangled. I ended up drilling the chuck body, and mounted the chuck to the backing plate, using bolt thru the chuck face, into threaded holes in te backing plate.
jack