Here is my hacksolution to truing up deep juice grooves. Deep juice grooves have end grain on both sides, so it’s both difficult and important to sand them well.
Here’s a video showing my method of choice for removing the dried epoxy leftover from filling the knot holes. This allows quick removal of the epoxy, with very little risk of damaging the wood underneath.
I found some parallel clamps on sale, so naturally, I needed a rack to hang them on. Legos, to the rescue!