I am planning on laminating two layers of 9mm baltic to make a substrate with Unibond 800. In case someone is wondering why, this method give me a very flat substrate that I can't get with a single 3/4" plywood substrate.
I have done this many times in the past and didn't concern myself that the two interior layers were facing in the same direction. Every time I discuss this with other woodworkers I get a horrified response that I glued two layers in the same direction but no one can articulate why this would be an issue. My final face veneers are oriented 90 degrees to the substrate face.
I wanted to get opinions if you all felt a breaker layer would be necessary and why?
What would you use for an inexpensive breaker layer if you recommend one?
I also know I could use 3 layers of 6mm but that is more expensive/more labor and feels unnecessary to me.
Subject : RE: laminating plywood Posted : 2020-10-26 8:38 AM Post #37966 - In reply to #37962
Every time you add a glue line you gain more stability so adding a cross banding layer in the middle will enhance this. Also, its industry standard to have a odd number of laminations in a lay up. You have two or more glue lines pulling against its opposite with odd number laminations. Is it an absolute must? No, but it can add a extra stability. If you’ve done it before with good results with just two sheets then I wouldn’t worry about it.
Grain going in the same direction in the center of your panel is not such a big deal.