Some Thoughts on Safety

This seems like as good a time as any to interject some of my views on the safe use of woodworking machinery. Hearing protection, protective eye wear, and dust collection are givens in using any of the machines shown in my entries. The planer and jointer are relatively safe, requiring mainly that the operator stand out of the way of potential flying wood fragments and, in the case of the jointer, the use of push blocks rather than bare hands to feed the stock. I will cover safety issues for the band saw in my entry on resawing, but it is one of the safest available means of cutting wood. It is the table saw that sends the greatest number of people to the emergency room, both because it is found in so many home and professional shops and due to the dangers inherent in the machine itself.

The Classic Kickback Pattern

Most table saw accidents are the result of kickback. Kickback occurs when the wood being cut makes contact with the back of the blade, that is, the part of the exposed blade furthest from the operator. Because that portion of the blade is moving upward and towards the operator, such contact causes the wood to be lifted up and flung at the operator, often with considerable force. The flying wood can cause serious injuries in itself but, in addition, if the operator's hand is near the blade when kickback occurs, it can be thrown against the moving blade.

Most kickback injuries are hand injuries involving everything from lacerations to partial or full amputations. The photo at right shows the telltale pattern of kickback left on the underside of a piece of wood. Fortunately, I was not injured when this occurred and have since upgraded to a saw with improved safety features. My luck held, but it was a sobering experience.

The cardinal rule in avoiding kickback is never to cut freehand on a table saw. Ripping, or cutting lengthwise, should always be done with the aid of a rip fence, shown in the photo below. The rip fence must be adjusted so it is exactly parallel to the blade. Measurements should be made with an accurate machinist's rule at the front and back of the blade to verify the spacing. Squaring the fence with the front edge of the table is only reliable if you have verified that this edge is truly at right angles with the blade. Though the relationship can be adjusted on most saws, the procedure would easily provide enough material for an entry or two of its own.

T-Square Style Fence

A fence that cannot be relied upon to lock parallel to the blade each time it is moved is extremely dangerous and should be replaced. Fortunately, excellent replacement fences are available from a number of manufacturers. Their cost may exceed that of an inexpensive table saw, but the hand injuries they help prevent would surely be much more costly.

I have a preference for the t-square style of fence pioneered by Biesemeyer and widely copied by others. The fence and its guide rail are extremely rigid and accurate and, since the fence locks only at the front, it is impossible to lock it at an angle. The Biesemeyer knock-off that came with my saw is shown in the adjoining photo.

The rip fence should never be used to guide a crosscut, that is for cutting a piece of wood to length. I will cover crosscutting in my next entry on safety.

To be continued...