The planer knife mark calculator allows the user to calculator the scallop depth, feed per knife and knife marks per inch/knife marks per cm of a wood planer head, based on cutter head diameter, number of knives, head rpm and feed speed.  Also includes user selectable international numeric formatting conventions and Metric (SI) and Imperial (UK and US) units.

The planer rotating cutterhead knives create scallops on the planed board.  The depth of the scallop is dependent on the feed speed of the wood, the rotational speed of the planer cutterhead, and the number of cutterhead knives.

In the animation, when the camera zooms in, a highly exaggerated example of scalloping is shown on the planed board.

When the lumber is held down improperly by the shoe, the rotating cutterhead knives will force the board up as it cuts into the lumber.  This creates a deeper cut, called a snipe cut, at the beginning of the board.

The animation exaggerates the size of the snipe; however planer snipe is a serious flaw in the cutting process and should be avoided when possible by ensuring that the shoe holds down the lumber firmly.

Planer misalignment occurs when the cutterhead is not fully square to the board.  In this animation, the cutterhead is tilted at a slight angle, and this causes the lumber to be improperly cut.  The transparent area shows the amount of misalignment.

The cutterhead should be parallel to the guide surface in order to avoid this misalignment problems.