Why are marking knife blade angles so important?

Each marking knife comes with a cutting edge (or edges) set at an angle. This angle cannot be changed but can vary from knife to knife.  

The angle at which a blade is set can make it more suitable for certain tasks.

Small-angle (more acutely-angled) blades range from 50 to 65 degrees and large-angle blades from 65 to 75 degrees.

The angle is important when performing specific applications – for instance, a small-angle blade fits better into restricted spaces.

The angle can also help determine what position the marking knife should be held at, so it can perform to its strengths.

Both small-angle and large-angle blades cut better when the tip of the blade is used on the wood.

Marking knives with small blade angles

The smaller-angle knives are suitable for marking joints with narrow spaces such as dovetails. They can also be used for bench work such as simple marking with a straightedge.

The advantage of the small-angle blade is that it can reach into areas that would be inaccessible to the large-angle blade due to its ability to cut with the tip even when held at a relatively low angle. This effectively increases the reach of the blade, and enables the user to see better when marking in small recesses.

The knife should be held at an angle that allows the sharpest point of the blade (the tip) to make contact with the workpiece. This helps produce a more precise cut.

Even when a small-angle knife is held quite low, the tip will still do the cutting.

Holding the marking knife lower can also allow your index finger to be placed on top of the handle and give you extra control, which allows you to apply pressure in the areas where it is most needed.

Marking knives with large blade angles

Large blade angles are suitable for marking certain joints such as housing joints (dados) and tenons. They can also be used for simple bench work such as straightedge marking.

A large-angle knife needs to be held at a higher angle than a small-angle knife, to ensure that the tip does the cutting.