How A Planer Works

To thickness a board, a planer's spring-loaded teed rollers pull the workpiece under a fast-spinning cutterhead. A flat bed and extension tables support the workpiece.

How They Work

All of our test planers share the same basic anatomy. The heart of a planer is its cutterhead assembly. Mounted above the planer bed, this assembly includes the motor, a cutterhead that holds two planer knives, and a pair of rubber-covered feed rollers. (See drawing, above.) The rollers pull the wood through the cuttcrhcad at about 26 linear ft. per minute. The bottom face of a board, which must be flattened on a jointer or with a hand plane before you feed it into a planer, slides across a pair of bed rollers or across a thin, stainless-steel platen that rests on the bed. Infccd and outfeed extension tables provide extra support for long stock.

On most benchtop planers, the cutterhead assembly is mounted on two large, threaded screws and supported either by four guideposts or by the machine's stamped steel frame. Turning a crank moves the cutterhead up or down, to adjust for stock thickness and depth-of-cut. Only the I litachi is designed differently. Its cuttcrhcad remains fixed, while the planer bed moves up or down.

Except for the Japanese-made Hitachi, all of our test planers were manufactured in Taiwan. In fact, many of them are made by the same factory there— Chiu Ting. The Penn State, Reliant and Woodtck appear to be identical except for color and labels. And the AMT, Jet, Star and Sunhill—which represent a relatively new design on the market—all strongly resemble each other.

What's Important?

Quality of cut tops the list. Your planer should produce boards of uniform thickness, with a surface that requires only light sanding or scraping before finishing.

Right out of the box, all of our test machines produced acceptably smooth boards that varied no more than '/64 in. across their width. The new Delta 22-560, the Grizzly, and the Hitachi had the smoothest cuts of the bunch.

The Tradesman produced the most scalloped surfaces—small, parallel ridges across the width of a board. (Sec right photo, below.) We discovered that the cutterhead's two knife recesses weren't machined to equal depths. Resharpening the Tradesman's knives should narrow them enough to allow for proper adjustment and a good cut.

Snipe is an all-too-common aggravation with both benchtop and stationary planers. This miscut—which planes the

% The best and the worst. Low-angle light shows the smoothest surface, made by i the Hitachi planer (left), and the roughest surface, made by the Tradesman (right).


Here's how to decide which type of planer is right for you

If you're in the market for a thickness planer, you'll have to decide between buying a benchtop model or a stationary one. Answer these key questions and you'll be able to make the right choice.

• How big? Benchtop planers will surface boards up to 12 in. wide. Stationary models are available with width capacities up to 20 in. (See AW's 1997 Tool Buyer's Guide.) If you frequently need to plane wide, glued-up panels, consider a stationary planer. Also, larger machines have the stability to handle long, heavy stock that can cause a bench-top planer to tip. If you want to handle this heavy stuff with a lightweight planer, force it to act like a stationary model by bolting it down.

• How rough? A stationary planer is the way to go if you're planing a lot of roughsawn boards: It has the power to remove more wood in a single pass, so you'll get from rough to smooth quickly. Also, stationary planers are less likely to bog down when the thickness of a board increases slightly—an irregularity common to roughsawn lumber.

• How smooth? Benchtop planers may nol have the muscle of their big brothers, but they can produce smoother surfaces. Higher cutterhead speed does the trick. If you want boards that require a minimum of sanding or scraping, you can't beat a benchtop planer.

•How often? If you don't need to plane boards every time you go out to the workshop, a benchtop planer offers an obvious advantage: You can stow it out of the way until it's needed. Like other benchtop tools, benchtop planers are great if you have limited space in your shop.

• How expensive? Price priorities are at the bottom of this list, but they could easily be at the top of yours. If you need thicknessing capability but can't afford a stationary machine, invest in a benchtop model. It will serve you well until you're in a position to trade up.

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