Planes and grains
Woodworking hand planes are mostly used for cutting along, or parallel with, the grain of the wood being worked on.
However, there are several situations in which they are used across the grain.
What is wood grain?
Wood grain is the direction, texture and pattern of the long, fine fibres that make up a piece of wood
You can clearly see lines showing the direction of the grain in some pieces of wood.
However, end grain – which you see when you look at either of the two ends of a length of wood – looks entirely different.
Because you are looking at the ends of fibres that have been cut laterally (across rather than along), you see what looks like a matrix of pinpoints or tiny dots.
How planes are used in relation to grain
A scrub plane can be used at an angle of 45 degrees or so across the grain, so that it moves sideways and forwards at the same time, shaving off large amounts of wood.
Block planes are often used across the end grain of a workpiece. The lower angle of its iron is better at slicing the grain laterally.
Block planes are also used with the grain when, for instance, chamfering, which is the planing of the corner of a length of wood, for instance, a table leg, at an angle of 45 degrees.
However, some chamfers – often those that go all the way around a rectangle – may also be planed on the end grain.
Bench planes are generally used along the grain, in the direction of the lines formed by the grain, but may sometimes be used for cutting end grain in the absence of a block plane.
Specialist planes are generally used both along and across the grain. For instance, a rebate plane can be used to cut a rebate, or a step in the edge of the wood, either along or across the grain, and a grooving plane can cut a channel either along the grain (a groove) or across the grain (a dado).
It's easy to damage wood when planing across the grain.
The wood is susceptible to what's known as tear-out, or break-out, as the plane's blade passes over the far edge of the workpiece.
This can happen when either the end grain is being planed, or when one of the faces (the sides) of the wood is being planed across the grain – for instance, when a scrub plane is being pushed over a face at an angle of around 45 degrees to the grain.
Tear-out, sometimes referred to as break-out, happens when planing end grain, at the end of the cutting stroke, when the blade passes over the far edge of the wood. There are no grain fibres beyond the far edge to prevent the force of the blade from splitting the wood vertically.
Tear-out can also occur when planing the long sides and edges of wood, where wood is torn from the surface rather than being cleanly cut. Causes include planing against the grain, a blunt cutting edge and setting the mouth of the plane too wide.
One way to avoid tear-out when planing end grain is to clamp a piece of waste wood in contact with the edge of the workpiece.
This acts as a buttress, preventing any splintering of the edge.
Another solution is to plane just over halfway across in one direction, then switch direction, planing just over halfway again.
This way, the cutting edge never passes over the far edge, so there is no tear-out.
When planing across the face of a piece of wood at 45 degrees, tear-out can be prevented by first planing a bevel on to the far, top edge of the wood.
As long as you don't plane away the bevel completely while reducing the wood, it will not break out at the far edge.
What remains of the bevel can be removed later when planing the edges.
Grain can be a pain
In practice, because grain usually never runs in a perfectly straight line, saying that you are planing "along" the grain is often an over-simplification.
The grain may run slightly upwards or downwards. You might need to reverse the position of the wood to ensure you work with the grain, rather than against it.
Going against the grain might cause tear-out along the length of the wood.
Or the grain direction may vary randomly along the length of the workpiece, which can make the wood very attractive, but presents problems when planing.
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