This allows one to use the pointed end for pruning very tiny limbs and even individual leaves. To preserve this precise geometry, concave pruners should never be forced by cutting material that is too large or too hard. A general rule is to never cut material that is larger than one half the size of the pruner's cutting edge measured from heel to tip. When cutting near capacity in size or extra hard wood, it is recommended to use the portion of the blades near the heel, rather than near the tip. This utilizes the extra thickness of the blades near the heel as well as the better mechanical advantage resulting from this portion of the cutting surfaces being closer to the tool's pivot.
All tools have a range of useful performance.
If the limb is too thick for a concave pruner or has potential of splitting back into the bonsai, make the cut using a saw or large conventional pruner. The cut should be about one inch from the trunk. Then use a knob cutter to nibble away the stub and to contour the final wound surface on the trunk. Use of knob cutters is discussed later. The short blades and finger holes give excellent control, enabling the user to reach into interior parts of the bonsai for trimming with precision.