Ryobi DBJ50 Operations Instructions download pdf (Page 19)

Page 10 Power Equipment Usage Manual (Rev. 5/10)

4. How to Prepare a Board

4.1. Reading Grain Orientation

Improper feed direction can ruin the work piece and can represent a danger to the

woodworker! The grain must slope away from the cutters edge. Be sure you

know which way the cutter is turning!

If wood is machined in the wrong direction:

• The edges of grain lines can lift or separate, requiring additional sanding to achieve a smooth

surface.

• A cutter can catch the edge of a grain line and may contribute to kickback.

• A cutter can catch the edge of a grain line and may fracture the workpiece.

While present everywhere in wood, the most visible grain is at the growth rings. Because we can readily

see growth rings, they are used to determine grain orientation in a piece of wood. If you are uncertain

as to the grain orientation, ask someone in the Woodshop for assistance.

To describe the cutter rotation direction versus the grain direction, the following terminology is used:

• When the cutter is working ‘down’, or ‘with the grain’, the bundles are sliced cleanly, leaving a

smooth surface with minimal defects.

• If the cutter is working ‘up’, or ‘against the grain’, the grain can snag or lift. The resulting surface

could be rougher than anticipated and require considerable sanding to correct.

The portion of the cutter meeting the wood turns against the direction of feed. That is a constant with

routers, jointers, planers, table saws and their hand-held equivalents. This is also true of belt sanders,

making grain direction important in their use as well.

Marking the grain direction noted on both sides of the wood can help prevent mistakes when sending it

through a machine (see Section 4.2 below). Very often opposing sides of a board must be fed in opposite

directions to maintain proper grain orientation in relation to the cutter.

Occasionally a piece of wood has grain that appears to run parallel to its length. In these cases, correct

feed direction can be virtually impossible to determine visually. When in doubt, make an educated

guess, followed by close inspection of the freshly machined surface to determine the best direction to

feed the workpiece.

• Often one feed direction produces a noticeably smoother surface than the other. Sometimes the

difference can be very subtle.

Cutter working ‘down’, or

‘with the grain’

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Ryobi DBJ50 Operations Instructions Page 19