I was having a hard time clamping a Thompson 1/4 inch detail gouge because the place that it needed to be clamped was at the end of the trough. The brass clamp could not clamp both sides properly. I figured that I needed to grind a flat on the top of the gouge, and discovered a simple way to make sure that the flat area was parallel to the wings of the gouge. I turned the gouge upside down, placed the tool guide very close to the stone, and set the gouge directly on the guide with the wings down. Then I was able to slide the gouge up and down against the wheel and get a grind centered on the top of the gouge. It took a while, but I got a very satisfactory flat on the top that enabled me to clamp the gouge.