Identify the machine before measuring the knife
Record the machine make, model, knife mounting position and quantity. Photograph both faces, the cutting edge and mounting holes with a scale in view. Do not infer dimensions from perspective photos alone. Worn dimensions must not be used directly as manufacturing dimensions for a new knife.
Record critical dimensions on one drawing
For circular knives, record outside diameter, bore, thickness and keyway. For straight blades, record length, width, thickness, hole spacing, counterbore direction and cutting-edge direction. For shredder knives, record the profile, bore, tooth count and adjacent spacers. Mark any dimension that requires further verification.
When a sample may be useful
Discuss sending a sample when the bore is irregular, the cutting edge is complex or the fit is unclear. State whether the used knife has been reground, chipped or deformed, and provide mating-part information where possible. Production must follow the drawings and technical requirements approved by both parties.