This is the tool that best fits the literal meaning of 'combination knife'.

Composition:

Two external saw blades: usually thin saw blades with oblique teeth, used to form a smooth cut surface of the groove wall.

Multiple internal gaskets: different thicknesses of chipper blades (with several teeth) and pure gaskets (shims).

Working principle: These blades and washers are stacked together in a specific order and installed on the shaft of the table saw. By adjusting their combination, precise grooves with widths ranging from a few millimeters to tens of millimeters can be assembled.

Main purpose:

Make mortise and tenon slots for drawers.

Create mortise and tenon structures for bookshelves.

Any woodworking project that requires precise width square grooves.