I just finished binding a LP style body with a 7 layer ivoroid/black and a 5 layer on the back. I used the Stewmac celluloid nitrate binding and their binding glue. Sounds like same stuff you used. I used acetone to laminate the narrow 0.040 strips together, three for the top and two for the back. My final piece was a plain ivoroid strip for both top and back. After laminating, I pre-shaped the binding by taping it to the body using a little heat (from a hair dryer) to help it conform to the bends. After it sat for a few days, I removed all the tape, then I glued the binding on the body by gluing the laminated strips to the body and the final ivoroid strip to the laminated strips. So I only had two glue areas to build up and add any thickness. The acetone adds no thickness when laminating. I had cut the top binding channel fairly close, and it turned out a little thick as you experienced, but not so much that some work with a scraper couldn't fix. Based on that, I cut the back channel a little deeper and it came out almost flush. I used my own bits, but I notice that Stewmac sells binding cutting bits that they advertise as being a little oversize to account for the glue, etc. Hope this is clear. Here is a pic of the top.