Stitch Groovers and Channelers
Stitch groovers are used to make a groove to allow your stitching to lay below the surface of the leather and be less subject to wear.
Compass Style Stitch Groovers
Compass Style Stitch Groovers are used to make a stitch groove parallel with the edge of your leather.
Patent Leather Tools or Freehand Stitch Groovers
Patent Leather Tools or Freehand Stitch Groovers are small narrow gouges used to cut a small channel for stitches to lay into. They can be used anywhere on a piece to make a sewing groove. They also can be used to cut the top of stitches to remove stitching - useful for relining saddle skirts or doing repair work without picking stitches one at a time.
Channelers
Channelers are used to cut a slit in the leather to sew into and then the slit is closed to protect the stitches from wear. They are mostly used by boot and shoe makers. Saddle makers use them to cut a slit in cantle bindings for doing a "hidden stitch" on the back. Straight channelers are known as American channel knives also.