I've bought all of my blades locally (Rockler), and they have only stocked the Olson #4 Spiral blades (as far as I've known). But, I wonder if (just maybe) I was using the wrong size blade for the thickness of that project. I had read, somewhere, that it wasn't good to really torque down on the blade holders, so I had always just gave them good tightening. I actually broke 4-5 blades and, for those that hadn't suffered breakage, they (more than a few times) kept slipping out of the lower blade holder. Now, the blade I was using is the Olsen #4 Spiral blade, and I had never broken a blade before - not until this project. Had I used one, on this project, the stock thickness would have been raised another 1/4" - giving me a 1" total to push through the blade. The first one could be remedied by the use of a 'sacrificial' bottom board, for what is resulted from the cutting characteristics of the blade, on that bottom piece. So, I secured three pieces of 16"x12"x 1/4" plywood together, and began with the project (the third one was supposed to be a gift for someone else). I'm not a seasoned scroll sawer, and (largely because of the number of internal cuts) I thought it would be nice to batch cut the portraits. She liked it so much that she wanted two more, as gifts to her two children. I had done two, before, with one of my sisters getting one.
Yesterday, I applied myself to scroll cutting more of the 'Christ with thorns' portrait patterns'.