The .c2d and .nc files for the slot are in the other thread (What’s going on here? #1) and I can provide the files for the flattening project if it would help?
I’m not sure how securing the stock is relevant to how CM works, but the flattening process was secured into a vertical and horizontal guide with Carbide 3D steel clamps, and the channel cutting as shown in the photo below:
The BitSetter was disabled for the flattening process but enabled for the channel cutting.
The axes zeros were set with the BitZero for the flattening process but visually (paper) for the channel cutting.
Both processes were run a few days apart, but the BitSetter re-enabled for the channel cutting, and I made sure to zero for this latest project as the flattening was completely different - and I always check the zero settings for each project unless, like in this case, I’m repeating the same project on the same piece of stock without a break, other than to adjust for Z.