For the last few weeks I've been playing around with making a jig to aid drilling chair seat mortises. It is not a new idea, I've seen similar jigs in chair making videos but with little detail on how they were made. Most of the time has been spent scratching my butt and playing the "yes but game" with little progress.
Here is where it is right now. I've been using a seat blank that split to try proof of concept and it seems to work. What is needed are wedges of the correct degree that will fit on both sides, there is too much flex with just the single shim.
Once correct sized wedges are in place the jig should work a treat.