Why a pilot hole is a good idea.

Many years ago I purchased a few different sized pencil-sharpener type tenon cutters and they came in handy for some small projects.  I still use them today, depending on the project.   I paid about $100 for each cutter.  The problem I had with them is that while cutting the tenon, I didn’t always hold my drill steady, and it resulted in gouged tenons.   It’s not a huge deal, but here’s a photo of what I mean.